(Topic ID: 272044)

Gottlieb The Games 80A No 5v and probably more problems

By honkbahh

3 years ago


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#1 3 years ago

Howdy!

I've had this machine over a year (bought it broken) and have finally accumulated the skills and time to hopefully get it working. It is Gottlieb's "The Games" system 80A. I have read https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#System_80_.2F_80A_Power_Supply many times (I don't claim to understand it), and have the instruction manual with all the schematic diagrams too (don't claim to understand these either). Also for these tests the only connection to the power board (A2) is J1. I believe I have replaced most of the recommended parts on the power board (I did that work a long time ago, including transistor at Q3), and have double checked all the work.

The immediate problem: the 5V led is not illuminated and the game does not boot. I've been looking at the schematics and don't understand where the 5V is supposed to be coming from, so I am having trouble figuring out what may be the issue. The 12V led lights up fine, and the 8V at TP5 checks out fine. I get no reading at the 60V and 42V TPs. If I am reading the schematics of transformers output to J1 on the power board correctly, pin 9 is +8V offset (don't know what offset refers to, but since the 8V test point works I assume its all good), pin 7 is 60V AC, pin 8 is 60V AC Return, pin 1 is 12V, pin 2 ground.

So following the schematic from pin 1 on J1 I don't know where the 5V is supposed to be generated. I see it referenced on pin 2 of the IC1 Regulator UA723CN (I tested it with my meter and got about .5v, but all the other pins referenced were outputting what the diagram shows. But since I don't understand the directionality of these things (as in, should that IC1 be outputting 5.1V at pin 2, or receiving 5.1V at pin 2, or if there even is such a thing as direction).

I also see 5.6V mentioned around the transistor at Q3 2N6057. Is this where I should be looking? This is one of the pieces I installed new, and checked for continuity from the legs at R11 and R9 as detailed in the article, and there is no continuity between Q3 and the cold plate.

Also, I read in the pinwiki that (referencing 80/80A) "Unlike the System 1 power supply, the +5 VDC logic power is no longer rectified and filtered on the power supply itself. This process is now handled by a bridge rectifier and a large filtering capacitor located on the transformer panel.", but how can that be true if board A2 at J1 does not have a 5V input, but then the board has 5V at a few places! I do see 5V at connectors J3 and J2, but since the guide says to look for the LEDs illuminated with those unplugged, I thought that board A2 will generate this 5V.

Any help is appreciated! Thank you!

Note: Dont worry about that mess at J3.

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#2 3 years ago

You have two main issues that need addressing.
Issue 1 -- low voltage supply.
The low voltage supply uses what is called a 'series pass' regulator. Transistor Q3 is used as if it was a 'variable resistor'. The regulator at IC1 turns the output voltage up and down by varying the base voltage of Q3. The output voltage from Q3 is set by varying IC1 pin 5's input voltage using the trimmer at POT1.

5V comes from emitter end of transistor Q3 and is tied to current sensing resistor R12. Opposite end of R12 is your final output voltage to your CPU and other boards. When there is too high of a voltage drop across R12 - the regulator at IC1 treats this as a shorted output and shuts down transistor Q3. One possible source of a short is the crowbar circuit - SCR1, CR8, R15 and R16. If the crowbar circuit detects too high of a voltage at output, it purposely shorts the 5V output forcing IC1 to treat the output as a short and shuts down.

If you have the voltage set too high at IC1 regulator (POT1) - this will force the output voltage to be too high. When you power up, this will instantly trigger the crowbar circuit which, in turn, shuts down IC1. Only way to clear the crowbar circuit is to shut off the power back off and turn it back on again. But if you didn't turn the voltage down - it goes right back into shut down again. Round and round and round we go. If the crowbar is causing the issues, turn voltage down at POT1 and then turn back up to 5V after machine is powered up (with nothing connected to J2 and J3).

The crowbar circuit is only one thing that can be causing the problem. Can also be bad components, bad connections or a combination of both.
I was going to ask if you were testing with both J2 and J3 were disconnected. But based on photo - J3 is hardwired. This should be the first thing you fix. Replace J3 with new header (e.g. Molex 26-48-1241) and J3 plug (e.g. CS156-07-LR with contacts 08-52-0113). While you're at it - avoid future head aches and replace J1 and J2 plugs/contacts since they are no doubt the originals. Plug at J1 - you have an IDC plug on that one so replace whole thing (CS156-09-LR plus contacts 08-52-0113 and one key 15-04-0219). Wire at pin 5 looks to be strung like a banjo wire - reroute him to take some strain off him. Plug at J2 - you can re-use existing plug or replace with CS156-06-LR (cheap) plus contacts 08-52-0113 and one key 15-04-0219.
Header:
https://www.greatplainselectronics.com/proddetail.asp?prod=26-48-1241
Plugs, contacts and keys:
https://www.greatplainselectronics.com/products.asp?cat=81

Need to separate the heat sink as few times as possible (done by removing Q3) -- each time you remove it, you risk damaging connections to the two press fit barrel contacts for his two leads. So don't rework until you know what is wrong. While still trouble shooting - since you cannot disconnect J3 (power to displays) then disconnect the display connectors instead.

First - lets get an over all picture of incoming voltages plus a few outbound -
With meter grounded to TP3 -- what voltage do you measure at following locations:
Connection point labeled "E4"
Connection point labeled "E5"
Connection point labeled "E6" (should be same as TP4)

Issue 2 -- high voltage supply.
Also a series pass regulator but his voltage is set by R1 and CR5.

With meter still grounded at TP3 -- what voltage do you measure at following locations:
Connection point labeled "E2"
Connection point labeled "E1"
Resistor R4, end closest to heat sink
Resistor R4 opposite end.

-------------------------------------------------
Revision -- note that the banjo wire on J1 is also connected to your 5V supply. He can also be the cause of your problems such as a bad 5V connection to a pop bumper driver board.

#3 3 years ago

I'm wondering why all 6 screws holding the coldplate and PCB together are screwed in from the PCB side. The threads are on the PCB side. The coldplate simply has holes. Unless you have nuts on the other side...
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#4 3 years ago

Thanks for the detailed reply! I had already removed the wires at J3, so did the tests with J3 and J2 disconnected. Also, I played with POT1 turning the machine on and off each time, and jiggled the “banjo wire” at pin 5 on J1, but no change. I’ll also order those parts once I see if I should order anything else.

Here are the measurements:
"E4": 15
"E5": .63
"E6" (should be same as TP4): .62

Issue 2 -- high voltage supply.:
"E2": .81
"E1": .81
Resistor R4, end closest to heat sink: .39
Resistor R4 opposite end: .39

I also measured at the J3 pins:
1: .39
3: 0
4: 0
5: 0
6: .63
7: .63

Similar readings at J2

Thanks!

#5 3 years ago
Quoted from ChrisHibler:

I'm wondering why all 6 screws holding the coldplate and PCB together are screwed in from the PCB side. The threads are on the PCB side. The coldplate simply has holes. Unless you have nuts on the other side...
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

I took the plate off to check all my work, then just stuck them on there for testing purposes so I didn’t lose them. I was worried about tightening them down (from the back) if had to remove them and Q3 again. Would those screws effect anything for these short tests?

#6 3 years ago
Quoted from honkbahh:

Would those screws effect anything for these short tests?

Not for testing continuity between the 2N6057 and the cold plate.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#7 3 years ago

If you don't have a good connection between Q3 collector (transistor case) and the press mount screw connections on the board then this supply won't work.
Do us a favor and take a picture of the opposite side of the hotplate particularly Q3.

#8 3 years ago
Quoted from G-P-E:

If you don't have a good connection between Q3 collector (transistor case) and the press mount screw connections on the board then this supply won't work.
Do us a favor and take a picture of the opposite side of the hotplate particularly Q3.

So, update! I flipped the screws and tightened it down properly, then fired up the machine. There was a slight hum this time, and smoke came streaming out of E6! So...?

508AA24F-D08E-4AEB-B674-410D43F52B5B.jpeg508AA24F-D08E-4AEB-B674-410D43F52B5B.jpeg
#9 3 years ago

OK -- better. But smoke came out of E6? or the resistor R12 at E5/E6?
Do you have the insulator installed between transistor and heat sink?
You may have voltage turned up too high on POT1 which forces the crowbar circuit (which *should* have forced IC1 to shut down Q3).

Hopefully somebody else can chime in - i gotta go for the day.

#10 3 years ago
Quoted from G-P-E:

OK -- better. But smoke came out of E6? or the resistor R12 at E5/E6?
Do you have the insulator installed between transistor and heat sink?
You may have voltage turned up too high on POT1 which forces the crowbar circuit (which *should* have forced IC1 to shut down Q3).
Hopefully somebody else can chime in - i gotta go for the day.

I am positive the smoke came from E6. Also, I turned the pot down while it was off. Now I get no smoke, and the 12v light is no longer illuminated.

Also, by insulator do you mean a bit of paste and a very thin plastic sheet? Cause that’s what I’ve got

#11 3 years ago
Quoted from honkbahh:

paste and a very thin plastic sheet

That should be a mica sheet...usually colored gold or yellow. It is shaped the same as the 2N6057 outline and isolates the 2N6057 from the coldplate (Ed calls it a hotplate).

I'd review your work again.
The only thing that I can see is that R10 appears to be only a 1/4W resistor. I use a 1/2W resistor there and always have. The reason for that I can not remember. That isn't causing the issue you are seeing though...just an FYI.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#12 3 years ago

It would take a LOT of current to make R12 smoke...perhaps residual flux at the solder connection was burning. Just a guess.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#13 3 years ago

Do yourself a favor unless you like to tinker and buy this:

https://ksarcade.net/rottendog-gps081-power-supply-for-gottlieb-system-80-a2-gps081.html

Bought one for the power supply that failed in my Caveman a year ago and it's ROCK SOLID!

#14 3 years ago
Quoted from CUJO:

Do yourself a favor unless you like to tinker and buy this:
https://ksarcade.net/rottendog-gps081-power-supply-for-gottlieb-system-80-a2-gps081.html
Bought one for the power supply that failed in my Caveman a year ago and it's ROCK SOLID!

That’s a last resort. I love to tinker!

#15 3 years ago
Quoted from ChrisHibler:

It would take a LOT of current to make R12 smoke...perhaps residual flux at the solder connection was burning. Just a guess.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

That was my first guess too, but now the 12v is out. Also, behind Q3 is a very thin clear plastic looking piece the same shape as Q3.

I took updated measurements, and maybe noticed something peculiar?

New readings:
"E4": .11
"E5": .47
"E6" (should be same as TP4): .47
Issue 2 -- high voltage supply.:
"E2": .46
"E1": .68
Resistor R4, end closest to heat sink: Fluctuates .16 to .03
Resistor R4 opposite end: .03
For the heck of it I tested some of the screws that mount the plate to the brackets on the back of the light board, (Not the screws attaching the pcb) and they each had a reading of about .35

I did the ground mod like pic 2 months ago (this is not a pic of my board).

Is it time to yank it out and remove Q3 again? I do fear for those pads a bit.

AF2E3C98-16F5-45C3-8E91-BD1320FE0468.jpegAF2E3C98-16F5-45C3-8E91-BD1320FE0468.jpeg81D6C310-25F0-44E5-8F53-5B14F5D6F406.jpeg81D6C310-25F0-44E5-8F53-5B14F5D6F406.jpeg
#16 3 years ago
Quoted from honkbahh:

That was my first guess too, but now the 12v is out. Also, behind Q3 is a very thin clear plastic looking piece the same shape as Q3.
I took updated measurements, and maybe noticed something peculiar?
New readings:
"E4": .11
"E5": .47
"E6" (should be same as TP4): .47
Issue 2 -- high voltage supply.:
"E2": .46
"E1": .68
Resistor R4, end closest to heat sink: Fluctuates .16 to .03
Resistor R4 opposite end: .03
For the heck of it I tested some of the screws that mount the plate to the brackets on the back of the light board, (Not the screws attaching the pcb) and they each had a reading of about .35
I did the ground mod like pic 2 months ago (this is not a pic of my board).
Is it time to yank it out and remove Q3 again? I do fear for those pads a bit. [quoted image][quoted image]

Following this thread - like your go getter attitude. Some of the best are helping you with this one - lots of knowledge!

#17 3 years ago
Quoted from SilverballSleuth:

Following this thread - like your go getter attitude. Some of the best are helping you with this one - lots of knowledge!

Thanks! I like everything except the back pain! This is my first machine. Since I got it I’ve acquired and fixed like 12 arcades and learned a lot, but they were less complicated. I got it for $250 and parts are cheap, so really nothing to lose.

#18 3 years ago
Quoted from honkbahh:

Is it time to yank it out and remove Q3 again? I do fear for those pads a bit.

You're going to need to review your work. There is no other way but to separate the halves again.
Those pads are pretty beefy. I've never damaged them. And, I've never seen them damaged even by the most brutal "tech".

The pic you linked is one of mine. Glad it helped.

While you have the boards apart again, replace those headers with new .156 "square" headers.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#19 3 years ago

You can more easily trouble shoot the high voltage supply with the heat sink removed.
Get that working before you re-assemble the heat sink to board connection for the low voltage supply.

Your E1 voltage (high voltage input) measured as non-existant. That is your incoming voltage. First thing to check --> the 60VAC fuse.

#20 3 years ago
Quoted from ChrisHibler:

You're going to need to review your work. There is no other way but to separate the halves again.
Those pads are pretty beefy. I've never damaged them. And, I've never seen them damaged even by the most brutal "tech".
The pic you linked is one of mine. Glad it helped.
While you have the boards apart again, replace those headers with new .156 "square" headers.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

Will do! I’d just like to order a bunch of parts at once to avoid $5 shipping a bunch of times.

#21 3 years ago
Quoted from G-P-E:

You can more easily trouble shoot the high voltage supply with the heat sink removed.
Get that working before you re-assemble the heat sink to board connection for the low voltage supply.
Your E1 voltage (high voltage input) measured as non-existant. That is your incoming voltage. First thing to check --> the 60VAC fuse.

Thanks! So just so I’m understanding, I’ll remove Q3, which has nothing to do with the higher voltage, and work on the higher voltage first. Plus check my work on everything else and find the source of the smoke, then leave Q3 off to do all the high voltage testing?

Also, is the fuse you referenced one of those in that line of fuses in the main cab? I think I have a bunch extra of those.

Thanks!

#22 3 years ago
Quoted from honkbahh:

So just so I’m understanding, I’ll remove Q3, which has nothing to do with the higher voltage, and work on the higher voltage first. Plus check my work on everything else and find the source of the smoke, then leave Q3 off to do all the high voltage testing?

Correct.

Quoted from honkbahh:

is the fuse you referenced one of those in that line of fuses in the main cab?

Also correct.
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact ... for board repairs
http://www.PinWiki.com - The Place to go for Pinball Repair Info

#23 3 years ago

1 Looks like I was lazy trimming some ends of parts I replaced and they scraped the cold plate. I checked a few of these places on the cold plate and got continuity across the plate. None of these scrapes are located at or near E5 and E6 though. I trimmed them right up, but I guess no reason not to replace r12 anyways right?

2 Maybe alarmingly, I can get continuity between all 4 of the holes on the cold plate of Q3 (2 for soldering, 2 for screws). I assume the continuity from the screws is ok, but from the poles!? I wouldn’t know how to fix this. Some type of paint? New plate? Electrical tape? I guess when I checked continuity from Q3 to the plate I should have tested it to some exposed silver Area I should make somewhere safe?

3 I do not get continuity from those metal rings at the through holes for Q3 to the solder-side of the board. I noticed this several days ago, but when I used enough solder with Q3 in place I got the continuity needed. Any advice here? Flood the back with solder around that ring?

4 I don’t see any damage to parts on the part side.

5 continuity from all the pins at J1 is good to the traces on the solder side.

6 all the soldering looks fine and continuity checked out for all parts.

7 I attached a pic of Q3 and maybe the insulating piece.

8 Fuses F2 and F3 we’re both blown (I put them in new when I originally got the machine). I replaced them, put A2 back in with the cold plate but no Q3, and it was dead to the world. No lights on the playfield or humming. Then after a few minutes I figured out I was a silly turd and didn’t plug that black fuse in fully. I powered the baby back up, and BINGO, 12V is back online!

New readings:
"E4": 15.25
"E5": .63
"E6" (should be same as TP4): .62
Issue 2 -- high voltage supply.:
"E2": 22.2
"E1": 22.5
Resistor R4, end closest to heat sink: 22.4
Resistor R4 opposite end: 22.9
J3 pin 1 24.3
Screw of plate to bracket .17

What should I replace and or check? Replace Q3 and make sure it’s for the correct insulation, and somehow repair the cold plate continuity issue? Solder jumpers to Q3 for testing purposes and avoid the plate? If I’m pulling something out for testing, I’d rather just replace it! Plus I may not have the tools to test it properly.

Thanks!

11B76792-7226-491E-80B6-43A278C4E5E1.jpeg11B76792-7226-491E-80B6-43A278C4E5E1.jpeg2199C51C-F0A3-492F-BDFC-69FDED7E9031.jpeg2199C51C-F0A3-492F-BDFC-69FDED7E9031.jpeg3011E1B7-9BCE-4831-B308-1A61CAF8FA88.jpeg3011E1B7-9BCE-4831-B308-1A61CAF8FA88.jpeg3EA2DDDE-180C-43AB-8AED-42D0E2ED6AD1.jpeg3EA2DDDE-180C-43AB-8AED-42D0E2ED6AD1.jpeg73ADC04D-29CC-4D40-86EE-237EB9C1499A.jpeg73ADC04D-29CC-4D40-86EE-237EB9C1499A.jpegA026A437-225B-49C8-91DE-6F056F7324BB.jpegA026A437-225B-49C8-91DE-6F056F7324BB.jpegD8A6B921-97E1-4F57-ADDD-30BF45B893C6.jpegD8A6B921-97E1-4F57-ADDD-30BF45B893C6.jpeg
#24 3 years ago

Those extra long leads under playfield could have been one of the issues but you have more.

Your #3 is what I was hoping to avoid with the statement about removing Q3 as few times as possible. Those can be real buggers to solder back down. Best bet here is to solder liberally. You may need to clean it up a bit to get off old flux and oxidation so solder will stick. Get some alcohol and clean around the holes and then use extra flux there to to get solder flowing. Gotta use a soldering iron with plenty of umpf as well, some of the smaller irons can't heat up that much copper.

Other issues:
Very first issue I see is your new Q3. You have a 2N6259, original was 2N6057 (or 2N6059). 2N6259 is a regular NPN type transistor, 2N6059 is an NPN Darlington type transistor -- big difference. Correct alternate for this one is 2N6284.

Second issue I see is the torn mica insulator on your Q3. You must replace that entirely. The transistor must NOT make contact with the heat sink. This addresses your number 2 statement above.

Third issue is that I cannot see your far side insulator that gets sandwiched between heat sink and pc board. Trying to see it through the screw hole in your last photo but cannot tell if it is there or not. This has appendages that insulate the holes through the heat sink so that the screws and transistor leads don't short to the heat sink. See below image for what this insulator looks like. Two large extrusions fit into screw holes of heat sink, two smaller extrusions fit into lead holes of heat sink. The 18PTI1HDWOB fits like a glove.

But don't go putting him back together yet. You still have high voltage issues. Your E1 connection is way too low. With the extra long leads from earlier, you may have lost a diode or two from your bridge rectifier circuit (CR1 through CR4). We need to see what the *AC* voltage is for the transformer input. You can pick this up with one of the volt meter's leads to the banded end of CR1 and the other lead to the non-banded end of CR4. Meter must be in AC mode and should see about 60 volts.

So far it appears that you need:
Q3 -- 2N6284
Q3 mica insulator, keystone 4651 plus heat sink compound *OR* heat sink pad such as SP400-0.009-00-03. This replaces both mica insulator and heat sink compound. MUST make sure the heat sink pad is the electrically insulating type as some of them are not.
Q3 mounting hardware - Microplastics 18PTI1HDWOB
But don't order anything yet - we still haven't figure out the HV supply.

TO3_Insulator (resized).JPGTO3_Insulator (resized).JPG
#25 3 years ago
Quoted from honkbahh:

That’s a last resort. I love to tinker!

I like to tinker too..... to a certain point... I get it...

#26 3 years ago
Quoted from G-P-E:

Those extra long leads under playfield could have been one of the issues but you have more.
Your #3 is what I was hoping to avoid with the statement about removing Q3 as few times as possible. Those can be real buggers to solder back down. Best bet here is to solder liberally. You may need to clean it up a bit to get off old flux and oxidation so solder will stick. Get some alcohol and clean around the holes and then use extra flux there to to get solder flowing. Gotta use a soldering iron with plenty of umpf as well, some of the smaller irons can't heat up that much copper.
Other issues:
Very first issue I see is your new Q3. You have a 2N6259, original was 2N6057 (or 2N6059). 2N6259 is a regular NPN type transistor, 2N6059 is an NPN Darlington type transistor -- big difference. Correct alternate for this one is 2N6284.
Second issue I see is the torn mica insulator on your Q3. You must replace that entirely. The transistor must NOT make contact with the heat sink. This addresses your number 2 statement above.
Third issue is that I cannot see your far side insulator that gets sandwiched between heat sink and pc board. Trying to see it through the screw hole in your last photo but cannot tell if it is there or not. This has appendages that insulate the holes through the heat sink so that the screws and transistor leads don't short to the heat sink. See below image for what this insulator looks like. Two large extrusions fit into screw holes of heat sink, two smaller extrusions fit into lead holes of heat sink. The 18PTI1HDWOB fits like a glove.
But don't go putting him back together yet. You still have high voltage issues. Your E1 connection is way too low. With the extra long leads from earlier, you may have lost a diode or two from your bridge rectifier circuit (CR1 through CR4). We need to see what the *AC* voltage is for the transformer input. You can pick this up with one of the volt meter's leads to the banded end of CR1 and the other lead to the non-banded end of CR4. Meter must be in AC mode and should see about 60 volts.
So far it appears that you need:
Q3 -- 2N6284
Q3 mica insulator, keystone 4651 plus heat sink compound *OR* heat sink pad such as SP400-0.009-00-03. This replaces both mica insulator and heat sink compound. MUST make sure the heat sink pad is the electrically insulating type as some of them are not.
Q3 mounting hardware - Microplastics 18PTI1HDWOB
But don't order anything yet - we still haven't figure out the HV supply.[quoted image]

AC voltage CR1 banded end to non banded C4: 25.2

Also, here is a pic of that Q3 spacer I have.

C1E45C7C-AE45-410B-B64E-4E69B4FCCAC5 (resized).jpegC1E45C7C-AE45-410B-B64E-4E69B4FCCAC5 (resized).jpeg
#27 3 years ago
Quoted from G-P-E:

Second issue I see is the torn mica insulator on your Q3. You must replace that entirely. The transistor must NOT make contact with the heat sink. This addresses your number 2 statement above.

Especially when the "standard" Ground Mod is performed. It will short the 12 Volts to GND. It is the reason why I personally never use the heatsink as a common for the GND and like to choose another point ( lower Hinge in system 80 and mounting pount of the backplate in system80A ) as a common for GND when performing Ground Mods.

#28 3 years ago
Quoted from honkbahh:

AC voltage CR1 banded end to non banded C4: 25.2
Also, here is a pic of that Q3 spacer I have.

You have a problem with the 60 volt AC voltage coming in from the transformer to pins 7 & 8.
Disconnect the plug from the power supply J1 and measure the AC voltage directly at the transformer. You'll need your game's manual to see which lugs you need to measure.

The Q3 insulator has a broken leg. Replace it with the 18PTI1HDWOB and install new mica/heatsink compound or thermal pad.

#29 3 years ago
Quoted from G-P-E:

You have a problem with the 60 volt AC voltage coming in from the transformer to pins 7 & 8.
Disconnect the plug from the power supply J1 and measure the AC voltage directly at the transformer. You'll need your game's manual to see which lugs you need to measure.
The Q3 insulator has a broken leg. Replace it with the 18PTI1HDWOB and install new mica/heatsink compound or thermal pad.

I’m having trouble taking the measurements. I think lugs are those metal pieces with wires soldered to them coming out of both top sides of the transformer?

Nothing is labeled on the transformer itself, and I am having trouble reading the schematic. I’m not sure which drawings corresponds to the transformer itself, and I see way more numbers on the schematic than actual lugs. Should I be looking to the right of that dashed box labeled 23836? I see two lines, labeled 1 and 2 that say 60V (and line 1 mentions F3 too), but I don’t know how these numbers relate to the lugs.

So in AC mode (with J1, J2, and J3 disconnected from A2) I connected what I would think would be lugs 1 and 2, on adjacent lugs (I checked all 4 corners of the transformer if that makes sense). The best reading I got was a couple 30s.

I also checked some combinations of fuses, and got 28v when I measured F1 and F2.

Can I get some help with what to poke, or how to interpret the schematic?

Thanks!
C5D2C222-7310-4B5E-839C-9AB7781FDD53.jpegC5D2C222-7310-4B5E-839C-9AB7781FDD53.jpeg56BC81B9-FB88-40BD-A36A-68454F0E0A2D.jpeg56BC81B9-FB88-40BD-A36A-68454F0E0A2D.jpegA425622A-0A6B-495A-BDFC-83A9664A7FD2.jpegA425622A-0A6B-495A-BDFC-83A9664A7FD2.jpeg

#30 3 years ago

I have doubts about these voltages - I don't think these are being read quite right.

Meter in AC mode - one lead on transformer lug #1, other lead on transformer lug #2.
"Lugs" are metal extensions where wire is soldered to transformer. The problem is - which is lug #1 and which is lug #2?
Lugs are labeled on top of transformer in black. Tough to read because the transformer sleeve is turning black.
lug #1 is identified as wire color "888", lug #2 is identified as wire color "111".
888 says gray wire with gray stripes --> Gray wire. 111 says brown with brown stripes --> brown wire. Which, of course, I do not see either a gray or brown wire.

I haven't ever had to mess with the transformer before so maybe somebody else here knows which lug is which on these transformers.
Else, You're going to need to trace wires back to get to the proper leads. Fuse 3 should be the easiest one to trace back.

#31 3 years ago
Quoted from G-P-E:

I have doubts about these voltages - I don't think these are being read quite right.
Meter in AC mode - one lead on transformer lug #1, other lead on transformer lug #2.
"Lugs" are metal extensions where wire is soldered to transformer. The problem is - which is lug #1 and which is lug #2?
Lugs are labeled on top of transformer in black. Tough to read because the transformer sleeve is turning black.
lug #1 is identified as wire color "888", lug #2 is identified as wire color "111".
888 says gray wire with gray stripes --> Gray wire. 111 says brown with brown stripes --> brown wire. Which, of course, I do not see either a gray or brown wire.
I haven't ever had to mess with the transformer before so maybe somebody else here knows which lug is which on these transformers.
Else, You're going to need to trace wires back to get to the proper leads. Fuse 3 should be the easiest one to trace back.

After some gentle cleaning I could read numbers on the transformer, but none of them were 1 or 2. I’ve attached a pic of my drawing.

Also no brown or grey wires. There is a white wire with grey stripes on the end of the fuse F3 closest to the transformer, but that wire goes into the base of the platform the transformer is sitting on.

Might these numbers help me read the schematics at all? Is my best bet to cut all the zip ties and follow wires from J1?

Thanks!

D619EFD8-6FBC-492F-BF0B-DB362105D1AA (resized).jpegD619EFD8-6FBC-492F-BF0B-DB362105D1AA (resized).jpeg
#32 3 years ago

So, from the schematic above of the transformer, starting at A12J3/A12P3 I was able to identify both the 60volt lines.

Line 888 (gray gray gray) goes from A12P3 to F3 fuse, as in the diagram, then on the other side of the fuse changes color to 100 (brown, black black) and goes into a hole in the platform supporting the transformer.

Line 111 goes from A12P3 to that same hole in the transformer, and I don't see it anywhere else.

I have no idea what those lines are doing in there, where/if they come out, and where that is even shown on the schematic.

So, I put one end of the meter at F3, and touched the other end to every lug on the transformer. They all registered 0. Next, I tried about 20 combinations of random lugs on the transformer. The highest I was able to conjure was 50, but I certainly didn't try all combinations.

I don't know what to try next.

#33 3 years ago

On the transformer assembly, remove F3 and buzz it.

Next, remove J1 from the power supply board. Power on. Measure AC voltage between pins 7 and 8. There should be about 60VAC.

Let us know.

I doubt anything is wrong with the transformer.

Probability in order:
1. Blown F3
2. Poor connection at 15 pin molex that connects transformer to power supply (A12J3/P3).
3. Broken wire on either side of 60VAC circuit.


Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
http://www.PinWiki.com/ - The new place for pinball repair info

#34 3 years ago
Quoted from ChrisHibler:

On the transformer assembly, remove F3 and buzz it.
Next, remove J1 from the power supply board. Power on. Measure AC voltage between pins 7 and 8. There should be about 60VAC.
Let us know.
I doubt anything is wrong with the transformer.
Probability in order:
1. Blown F3
2. Poor connection at 15 pin molex that connects transformer to power supply (A12J3/P3).
3. Broken wire on either side of 60VAC circuit.

Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
http://www.PinWiki.com/ - The new place for pinball repair info

I have seen #2 twice.. so not unheard of.

#35 3 years ago
Quoted from ChrisHibler:

On the transformer assembly, remove F3 and buzz it.
Next, remove J1 from the power supply board. Power on. Measure AC voltage between pins 7 and 8. There should be about 60VAC.
Let us know.
I doubt anything is wrong with the transformer.
Probability in order:
1. Blown F3
2. Poor connection at 15 pin molex that connects transformer to power supply (A12J3/P3).
3. Broken wire on either side of 60VAC circuit.

Chris Hibler - CARGPB #31
Http://chrishiblerpinball.com/contact
http://www.PinWiki.com/ - The new place for pinball repair info

Ok big update! I don’t exactly understand what you meant by checking the voltage at pins 7 and 8 on A2 J1, because all of A2 is unplugged and would read nothing, so I think you were telling me to insert something into the A2J1 plug and check measures that way?

Either way my meter probes wouldn’t fit inside, so I checked the F3 fuse... And it failed! I put a new one in two days ago, but I must admit I didn’t test it before I put it in. I also looked at my previous posts and couldn’t figure out how I may have blown that new fuse. So I replaced it with a new one, and got much better measurements!

AC voltage CR1 banded end to non banded C4: 62

high voltage supply.:
"E2": 64.6
"E1": 82.6
Resistor R4, end closest to heat sink: 64
Resistor R4 opposite end: 64.1
J3 pin 1 64
J3 pin 3 46

I didn’t really do anything to fix this, but maybe a juggled plug or connection like you mentioned. Looking good? Next steps?

#36 3 years ago

HV is working now. Fuses can be deceiving.
Time to put the low voltage supply back together. But before you do - you need three new items as mentioned at the end of post 24 above.

Note - the reason we didn't see the transformer connections is they connect on both sides of transformer. Part of the connections cannot be seen without flipping the transformer section over and looking at it from below. Not safe as it has the 120VAC house power exposed there. But now that you have the HV supply working - it no longer matters.

#37 3 years ago
Quoted from G-P-E:

HV is working now. Fuses can be deceiving.
Time to put the low voltage supply back together. But before you do - you need three new items as mentioned at the end of post 24 above.
Note - the reason we didn't see the transformer connections is they connect on both sides of transformer. Part of the connections cannot be seen without flipping the transformer section over and looking at it from below. Not safe as it has the 120VAC house power exposed there. But now that you have the HV supply working - it no longer matters.

Bueno! I’m assembling a purchase list, and I’ll confirm it here. Is there anything else you recommend I buy just in case? It’s quite possible other parts of the machine will have issues.

Also, for replacing the pins on A2 and the plug heads, if I cut the wires, they will be too short to reach the connections. So should I cut and extend them, or get some type of pin extractor to pull them out of the plug? Or does that defeat the purpose?

#38 3 years ago

Headers -- 26-48-1241 to replace those awful round pins. These can sometimes be a bugger to change as sometimes the holes are too small. Fortunately, this is a single sided board so reaming out the hole a tiny bit won't hurt.

Plugs - often you cut the ends off but as little as possible. Sometimes you need to take up slack within the wiring harness to keep the wires long enough. No extractor for plug 1 - clip them. Replace plug with standard type plugs that have the discrete crimp type contacts (more like plug 3).
Plug 2 - non existant so must clip and replace. Plug 3 - you can reuse the body. Just use a small jeweler's screw driver to push the old contact's tang in and then pull wire out back. But an entirely new plug 3 is less than 20 cents.
For example's of plugs and contacts -- see here:
https://www.greatplainselectronics.com/products.asp?cat=81
You will also need new crimp contacts and one key per plug (can see them on same web page).
And - if you don't have a crimper, good time to look at them as well. If you do very few connectors then you can just use a low cost crimp tool such as the Waldom W-HT-1919.

As far as the remainder of boards - hard to tell what you need until you get game to test mode. You may need to repin some edge connectors. For those, use 08-52-0072 type contacts.

And for lots of good information -- see here:
https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80

#39 3 years ago
Quoted from G-P-E:

Headers -- 26-48-1241 to replace those awful round pins. These can sometimes be a bugger to change as sometimes the holes are too small. Fortunately, this is a single sided board so reaming out the hole a tiny bit won't hurt.
Plugs - often you cut the ends off but as little as possible. Sometimes you need to take up slack within the wiring harness to keep the wires long enough. No extractor for plug 1 - clip them. Replace plug with standard type plugs that have the discrete crimp type contacts (more like plug 3).
Plug 2 - non existant so must clip and replace. Plug 3 - you can reuse the body. Just use a small jeweler's screw driver to push the old contact's tang in and then pull wire out back. But an entirely new plug 3 is less than 20 cents.
For example's of plugs and contacts -- see here:
https://www.greatplainselectronics.com/products.asp?cat=81
You will also need new crimp contacts and one key per plug (can see them on same web page).
And - if you don't have a crimper, good time to look at them as well. If you do very few connectors then you can just use a low cost crimp tool such as the Waldom W-HT-1919.
As far as the remainder of boards - hard to tell what you need until you get game to test mode. You may need to repin some edge connectors. For those, use 08-52-0072 type contacts.
And for lots of good information -- see here:
https://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80

I'm not sure which crimp contacts to get. I tried to read up, and saw conflicting info. Some said not to use Trifurcon on edge connectors or Gottlieb machines? Also, I couldn't find the AWG in the manual, so what size should I get?

I've also attached a pic of the crimpers I have (neither of which I have used very much). Thanks!

IMG_7446 (resized).jpgIMG_7446 (resized).jpg
#40 3 years ago

2445A - that is for use with these 0.156" contacts.
It includes a 'locator' -- if the locator works properly then this is a great crimp tool to use.

For Gottlieb edge connectors (e.g. CPU board and driver board) - you must NOT use trifurcon type contacts there.
For the three connectors on the Gottlieb power supply board - you can use either flat or trifurcon type contacts.
For Gottlieb machines - if buying just one type, go with the flat contacts.
Wire sizes - the contacts overlap so not as critical. Just use 08-52-0072 for all the contacts (covers 18-22AWG) - both power supply and edge connectors.

The black double sided edge connector - mess with that one as little as possible. The contacts for those have become difficult to locate.

#41 3 years ago
Quoted from G-P-E:

2445A - that is for use with these 0.156" contacts.
It includes a 'locator' -- if the locator works properly then this is a great crimp tool to use.
For Gottlieb edge connectors (e.g. CPU board and driver board) - you must NOT use trifurcon type contacts there.
For the three connectors on the Gottlieb power supply board - you can use either flat or trifurcon type contacts.
For Gottlieb machines - if buying just one type, go with the flat contacts.
Wire sizes - the contacts overlap so not as critical. Just use 08-52-0072 for all the contacts (covers 18-22AWG) - both power supply and edge connectors.
The black double sided edge connector - mess with that one as little as possible. The contacts for those have become difficult to locate.

Thanks! Cart is all assembled, but the keying plug only has 1 in stock. Do you have a recommended replacement? I'll place the order once the shop opens back up!

1 week later
#42 3 years ago
Quoted from G-P-E:

2445A - that is for use with these 0.156" contacts.
It includes a 'locator' -- if the locator works properly then this is a great crimp tool to use.
For Gottlieb edge connectors (e.g. CPU board and driver board) - you must NOT use trifurcon type contacts there.
For the three connectors on the Gottlieb power supply board - you can use either flat or trifurcon type contacts.
For Gottlieb machines - if buying just one type, go with the flat contacts.
Wire sizes - the contacts overlap so not as critical. Just use 08-52-0072 for all the contacts (covers 18-22AWG) - both power supply and edge connectors.
The black double sided edge connector - mess with that one as little as possible. The contacts for those have become difficult to locate.

Ok, here’s where we’re at. Got the new parts. I installed the new Q3 with the insulation pad and plastic spacer thing, and replaced the pins on the board and wired new connectors (my first time!) for board A2. I also made a better connection on the through holes for Q3 to the solder side of the board.

I fired the game up, and got a tiny bit of smoke for a brief moment from the same general area as last time, just much less, and do not have 5V or 12V led illuminated.

I tried to reflow Q3 on the parts side, but no change. I also checked continuity from Q3 to some resistors, and it’s soldered in properly. I also gave all the wires a jiggle, and checked for continuity from every component I could touch on the parts side of the board to an exposed portion of the plate by the corner, but didn’t get any continuity.

I also remeasured all the points voltage:

AC voltage CR1 banded end to non banded C4: 63.5

With meter grounded to TP3 -- what voltage do you measure at following locations:

Connection point labeled "E4": 1.4
Connection point labeled "E5": .47
Connection point labeled "E6" (should be same as TP4): .47
** because why not I also measured:
Q3 top: .36
Q3: bottom: 1.48
E3: 8.02
E4: 1.4
R17 top: 1.4
R17 bottom: 1.4
**
C1+: 82.6 DC and 182.3 AC (not sure if this is normal??
C1 -: 0 DC and AC.
(I measured the AC using TP3)
**

Issue 2 -- high voltage supply.
Also a series pass regulator but his voltage is set by R1 and CR5.
With meter still grounded at TP3 -- what voltage do you measure at following locations:
Connection point labeled "E2": 65
Connection point labeled "E1": 84
Resistor R4, end closest to heat sink: 64.4
Resistor R4 opposite end: 64.6

I also measured at the J3 pins:
1: 64.4
3: 46.6
4: 0
5: 0
6: .47
7: .47

Also, I am still reading about .2V DC at the screws mounting the plate. This doesn’t seem normal...?

Any suggestions? The only thing I can think of is to try to run it briefly with everything installed except the plate, or cover any suspicious spots on the plate with electrical tape.

Thanks!
01542B45-1B65-4A4F-BDA9-23E4356E1DFC (resized).jpeg01542B45-1B65-4A4F-BDA9-23E4356E1DFC (resized).jpeg4589C6BF-D89E-4339-819F-C5ED7D28F66F (resized).jpeg4589C6BF-D89E-4339-819F-C5ED7D28F66F (resized).jpeg9C85A599-D90B-49A5-95BB-0111C986904C (resized).jpeg9C85A599-D90B-49A5-95BB-0111C986904C (resized).jpegFAE3BD7F-316A-4D7D-9B7D-92EFE63E3DEA (resized).jpegFAE3BD7F-316A-4D7D-9B7D-92EFE63E3DEA (resized).jpeg

#43 3 years ago
Quoted from honkbahh:

Ok, here’s where we’re at. Got the new parts. I installed the new Q3 with the insulation pad and plastic spacer thing, and replaced the pins on the board and wired new connectors (my first time!) for board A2. I also made a better connection on the through holes for Q3 to the solder side of the board.
I fired the game up, and got a tiny bit of smoke for a brief moment from the same general area as last time, just much less, and do not have 5V or 12V led illuminated.
I tried to reflow Q3 on the parts side, but no change. I also checked continuity from Q3 to some resistors, and it’s soldered in properly. I also gave all the wires a jiggle, and checked for continuity from every component I could touch on the parts side of the board to an exposed portion of the plate by the corner, but didn’t get any continuity.
I also remeasured all the points voltage:
AC voltage CR1 banded end to non banded C4: 63.5
With meter grounded to TP3 -- what voltage do you measure at following locations:
Connection point labeled "E4": 1.4
Connection point labeled "E5": .47
Connection point labeled "E6" (should be same as TP4): .47
** because why not I also measured:
Q3 top: .36
Q3: bottom: 1.48
E3: 8.02
E4: 1.4
R17 top: 1.4
R17 bottom: 1.4
**
C1+: 82.6 DC and 182.3 AC (not sure if this is normal??
C1 -: 0 DC and AC.
(I measured the AC using TP3)
**
Issue 2 -- high voltage supply.
Also a series pass regulator but his voltage is set by R1 and CR5.
With meter still grounded at TP3 -- what voltage do you measure at following locations:
Connection point labeled "E2": 65
Connection point labeled "E1": 84
Resistor R4, end closest to heat sink: 64.4
Resistor R4 opposite end: 64.6
I also measured at the J3 pins:
1: 64.4
3: 46.6
4: 0
5: 0
6: .47
7: .47
Also, I am still reading about .2V DC at the screws mounting the plate. This doesn’t seem normal...?
Any suggestions? The only thing I can think of is to try to run it briefly with everything installed except the plate, or cover any suspicious spots on the plate with electrical tape.
Thanks!
[quoted image][quoted image][quoted image][quoted image]

#44 3 years ago

Small update. I decided to check the fuses inside at the main fuse box again, and F2 had blown again. So, I replaced it and fired it up again. There was a brief louder than normal hum, and a little bit of smoke again from the same general area. I rechecked F2 and it blew again. So why the hell not, I replaced it and tried it again, this time having my wife turn it on so I could try to pinpoint the exact location of the smoke. However this time there wasn’t smoke. I pulled the fuse, and it was blown. Any place in particular I should check on A2 besides the region of the smoke? I don’t fully understand the routing to arrive at fuse F2, but I assume it’s after A2.

I double checked, and the fuses I am using are 5A slow blow fuses.

#45 3 years ago

R12 should not be smoking. This is your current sense resistor used for detecting shorted outputs and is *supposed* to turn off the Q3 transistor when the voltage drop across R12 gets too high (e.g. shorted output at E6).

Sounds like you have two problems:
1 -- If there is a short - it is most probably SCR1/CR8 related. CR8 is used to detect excessive voltage from the regulator and is set at 5.6 volts. If it does detect excessive voltage, it instantly turns on SCR1. SCR1 puts a direct short across the regulator output ti force the regulator to shut down his outputs (turn down voltage at pin 10 of regulator). SCR1 is called a 'crowbar' circuit as it causes a direct short between the +5V power and ground - like throwing a real crowbar on power lines.
If SCR1 or CR8 are bad - this can cause the short to occur. Or if IC1 (regulator) is not working properly or is turned up too high at POT1 then the crowbar circuit could fire as soon as you turn on the power. **Did you try turning POT1 down?** Also, check soldering job at POT1, R7 and R14.
Note that once the crowbar circuit has triggered, it cannot be cleared until you power down the board.

2 -- Since R12 is getting hot then the regulator is not shutting down like he's supposed to -- resulting in blown fuses. I'm beginning to think the 723 regulator may be bad.

#46 3 years ago
Quoted from G-P-E:

R12 should not be smoking. This is your current sense resistor used for detecting shorted outputs and is *supposed* to turn off the Q3 transistor when the voltage drop across R12 gets too high (e.g. shorted output at E6).
Sounds like you have two problems:
1 -- If there is a short - it is most probably SCR1/CR8 related. CR8 is used to detect excessive voltage from the regulator and is set at 5.6 volts. If it does detect excessive voltage, it instantly turns on SCR1. SCR1 puts a direct short across the regulator output ti force the regulator to shut down his outputs (turn down voltage at pin 10 of regulator). SCR1 is called a 'crowbar' circuit as it causes a direct short between the +5V power and ground - like throwing a real crowbar on power lines.
If SCR1 or CR8 are bad - this can cause the short to occur. Or if IC1 (regulator) is not working properly or is turned up too high at POT1 then the crowbar circuit could fire as soon as you turn on the power. **Did you try turning POT1 down?** Also, check soldering job at POT1, R7 and R14.
Note that once the crowbar circuit has triggered, it cannot be cleared until you power down the board.
2 -- Since R12 is getting hot then the regulator is not shutting down like he's supposed to -- resulting in blown fuses. I'm beginning to think the 723 regulator may be bad.

Let me read up so I understand those terms a bit better. I have played with pot 1 a bit, but can play with it more. I’ll figure out which way is down and turn it all the way. I’ve got a few more fuses to burn.

#47 3 years ago
Quoted from honkbahh:

Let me read up so I understand those terms a bit better. I have played with pot 1 a bit, but can play with it more. I’ll figure out which way is down and turn it all the way. I’ve got a few more fuses to burn.

Ok, I'm comfortable replacing all those parts (I guess except for SCR1, which doesn't seem to go bad?). I figure since I have to take Q3 out again I may as well replace a few parts while I'm in there. I'll also check the soldering you mentioned. I'll order another Q3 just because, but is there a reason to suspect the new one got fried? Also, please let me know about any other parts I should order. Perhaps its possible I put POT1 in backwards or something (I don't even remember if I put that in, or if it is original).

Thanks!

#48 3 years ago
Quoted from G-P-E:

R12 should not be smoking. This is your current sense resistor used for detecting shorted outputs and is *supposed* to turn off the Q3 transistor when the voltage drop across R12 gets too high (e.g. shorted output at E6).
Sounds like you have two problems:
1 -- If there is a short - it is most probably SCR1/CR8 related. CR8 is used to detect excessive voltage from the regulator and is set at 5.6 volts. If it does detect excessive voltage, it instantly turns on SCR1. SCR1 puts a direct short across the regulator output ti force the regulator to shut down his outputs (turn down voltage at pin 10 of regulator). SCR1 is called a 'crowbar' circuit as it causes a direct short between the +5V power and ground - like throwing a real crowbar on power lines.
If SCR1 or CR8 are bad - this can cause the short to occur. Or if IC1 (regulator) is not working properly or is turned up too high at POT1 then the crowbar circuit could fire as soon as you turn on the power. **Did you try turning POT1 down?** Also, check soldering job at POT1, R7 and R14.
Note that once the crowbar circuit has triggered, it cannot be cleared until you power down the board.
2 -- Since R12 is getting hot then the regulator is not shutting down like he's supposed to -- resulting in blown fuses. I'm beginning to think the 723 regulator may be bad.

Some progress! I checked the soldering at POT1, and it was clean. However I checked continuity and got some between two of the traces, even though there was no bridge between the traces. I removed POT1 and checked continuity between the legs, and I was getting continuity. I figured either the POT1 was bad, or something fried it. I replaced POT1, R14, and IC1 (723) since they looked to be related to me.

I fired the machine back up, and now I get the 12V light, but still no 5V. Also, F2 is no longer blowing. (All the other fuses are good too). Here are updated measurements.
With meter grounded to TP3 -- what voltage do you measure at following locations:

Connection point labeled "E4": 12.1
Connection point labeled "E5": 1.6
Connection point labeled "E6" (should be same as TP4): .9
Issue 2 -- high voltage supply.
With meter still grounded at TP3 -- what voltage do you measure at following locations:
Connection point labeled "E2": 65.2
Connection point labeled "E1": 84.1
Resistor R4, end closest to heat sink: 64.5
Resistor R4 opposite end: 64.7

Q3 top: 1.67
Q3 bottom: 2.86

Also, after being on a minute or two the cold plate does heat up, and Q3 is soldered properly and no continuity to the plate.

Any suggestions? Replace Q3 again? I don’t know how to check if Q3 is being fed the correct voltage in the first place, but both my Q3 measures don’t sound normal, so I’d figure the problem is elsewhere. But then again if I’ve got to open it again maybe I might as well replace it. Thanks!
0D1279B4-7CE6-45A9-B295-3C25EDBECF26 (resized).jpeg0D1279B4-7CE6-45A9-B295-3C25EDBECF26 (resized).jpeg

#49 3 years ago

Was the pot rotor turned all the way to right or left? That will show up as continuity between the two.
You should get a fixed resistance of 500 ohms between the two outer legs. You will get varying resistance between the center leg and two outer legs -- anything from zero to 500 ohms.

For example - if you get 100 ohms between center pin and left pin then you should see (500 - 100) between center pin and right pin.

If you had the pot turned too far towards increasing voltage (usually to right but depends on how you installed pot) - this will crank up output voltage to a point where it will exceed CR8 voltage and fire the crowbar circuit.

Now -- all HV supply looks good so leave that section alone. 12V input is good.
Don't replace anything yet - they were all new parts so the likelihood of one being bad is slim.
We're now looking at control voltages going to Q3. First measure his input voltage - measure between case and ground - should also be in 12V range.
And make sure there is no short between the case and heatsink. If you already have heatsink grounded then this is quite unlikely since it would take out 12V supply.
Then carefully measure voltages around IC1 to make sure they conform to what the manual says.
Pin 5 at 2.5 (varied by turning POT1)
Pin 6 at 7.1 (should be fixed voltage in 6.8 to 7.5V range with 7.15 being typical)
Pin 10 at 7.0 (varied by turning POT1) (do not turn above 7V, much higher will trigger over voltage protection crowbar circuit)
Pins 11 and 12 at 12.1ish (same as 12V input voltage)
Best to measure directly on the IC to make sure the voltages are really getting to the device. Be careful not to short any pins to each other.

#50 3 years ago
Quoted from G-P-E:

Was the pot rotor turned all the way to right or left? That will show up as continuity between the two.
You should get a fixed resistance of 500 ohms between the two outer legs. You will get varying resistance between the center leg and two outer legs -- anything from zero to 500 ohms.
For example - if you get 100 ohms between center pin and left pin then you should see (500 - 100) between center pin and right pin.
If you had the pot turned too far towards increasing voltage (usually to right but depends on how you installed pot) - this will crank up output voltage to a point where it will exceed CR8 voltage and fire the crowbar circuit.
Now -- all HV supply looks good so leave that section alone. 12V input is good.
Don't replace anything yet - they were all new parts so the likelihood of one being bad is slim.
We're now looking at control voltages going to Q3. First measure his input voltage - measure between case and ground - should also be in 12V range.
And make sure there is no short between the case and heatsink. If you already have heatsink grounded then this is quite unlikely since it would take out 12V supply.
Then carefully measure voltages around IC1 to make sure they conform to what the manual says.
Pin 5 at 2.5 (varied by turning POT1)
Pin 6 at 7.1 (should be fixed voltage in 6.8 to 7.5V range with 7.15 being typical)
Pin 10 at 7.0 (varied by turning POT1) (do not turn above 7V, much higher will trigger over voltage protection crowbar circuit)
Pins 11 and 12 at 12.1ish (same as 12V input voltage)
Best to measure directly on the IC to make sure the voltages are really getting to the device. Be careful not to short any pins to each other.

Thanks again for all your help!

I checked the old POT1, and it was turned all the way down when I checked it for continuity.

I checked for continuity both at the screws that go through Q3, and the round portion of Q3, to the cold plate and nothing buzzed.

Voltage at both screws on Q3 to ground TP3 was 12.04

The voltages at the new IC1 were all on the money to what you mentioned except pin 10, which measured an anemic 2.8. Turning POT1 up and down had no affect on pin 10, but did change pin 5. In the schematic I didn’t understand what pins 3 and 4 should output.
IC1 voltages
1 0
2 1.51
3 .87
4 .42
5 2.5
6 7.28
7 0
8 0
9 0
10 2.8
11 12.03
12 12.05
13 4.06
14 0

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