(Topic ID: 207904)
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Quoted from LTG:I'd check the manual. Bridge rectifiers may be for coils or lights, mounted on the back like a big heat sink. Big thing is a big honkin capacitor.
LTG : )
Anyway to test the capacitor for integrity? Getting low volts at the TPs throughout. The bottom BR seems to be shorted, so I wonder if that may effect something..
Quoted from GRUMPY:These 2 BR do not have TPs on the power supply.
This BR is for CPU controlled lamps, in a different thread you said you only had 13 volts. This will be your low voltage problem on this one issue.
After replacing the BR to get the voltage back up to 19 volts, place DMM set to AC volts on the cap terminals and see how much AC is present.
You’re saying that this bottom shorted BR (not on PS, but attached to backbox), could be the reason for low voltage?
In regards to the big capacitor. Is it really safe to touch the positive and negative terminals with the DMM? Maybe I’ll take a reading before I replace this Br. I haven’t read this one yet.
Quoted from GRUMPY:https://pinside.com/pinball/forum/topic/low-readings-at-5v-12v-and-18v#post-4185671
This is the reason for the low 18 volt reading. The other low voltages are because you need to rebuild the power supply.
As long as you do it correctly.
As with most pins that you buy there are multiple problems that need attention.
Grumpy, I replaced the BR pictured above, but no luck. I get the following readings:
BIG Honking Capacitor: 13v
PSU:
BR1 = 23V
TP1 = 3V
TP2 = 0V (Think this is a ground TP)
TP3 = 9V
TP4 = -13V
CPU:
+5 = 3V
+12 = 9V
+18 = 13V
If BR1 on the PSU measures 23V shouldn't TP3 (next element down the line) measure 23V as well? I pulled the board and am about to replace BR1.
Quoted from GRUMPY:This power supply needs to be recapped at a bare minimum and then retested.
I recapped the entire Ps. Also replaced the BR1. Still low voltage. Could it be the transformer?
Quoted from GRUMPY:So what are the new readings on TP-1, TP-3 and TP-4.
They are the same as before. No change.
Quoted from GRUMPY:Did you change D-1,D-3, D-4, D-5 and D-6
I’m assuming those are the diodes. No I didn’t replace any diodes because they were working fine with the DMM on diode mode.
Quoted from GRUMPY:They don't always test bad, replace them and retest the TPs.
Ok I will replace these tomorrow. I truly appreciate your help. I am learning a lot 
Quoted from GRUMPY:They don't always test bad, replace them and retest the TPs.
Quick question, can I use a 1N4004 to replace the ZR1, ZR2 and ZR3 or do these have a totally different function? OR should I not be concerned with these?
Quoted from ChrisHibler:A 1N4004 is not a valid substitute for those diodes. Surf on over to greatplainselectronics.com and pick up a System 11 PS rebuild kit.
—
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info
k, Thanks. But any of the black ones with the silver strip I should be able to use 1N4004, correct? I think I see 8 in total
I replaced these diodes: D-1,D-3, D-4, D-5 and D-6
In regards to your previous message:
Quoted from GRUMPY:Set your DMM to AC volts and measure the 2 blue wires on the bridge rectifier. Should be 13.5 volts AC. If this reads low then test the AC outlet the game is plugged into with the game on.
13.5V
Quoted from GRUMPY:This should be 118-122 volts AC.
120V
Quoted from GRUMPY:If the AC on the blue wires of the BR is good then remove one wire from the big cap and put a piece on tape on it and retest the DC voltage on the purple wire and the black wire. If it has gone up from 13 volts to @ 18 volts then the big cap is bad.
9.5V
Quoted from GRUMPY:What are the TPs reading now?
They are measuring the same.
Quoted from GRUMPY:So you are getting 13.5 AC on the blue wires, correct? And you are getting 9.5 volts on the purple and the black wire with one lead removed from the big cap, correct? Then your brand new bridge rectifier is bad.
This is all correct. I tried with a new BR and I am still getting the same everything.
Quoted from GRUMPY:Something isn't adding up hear. There is a molex connector that connects the transformer to the wiring harness on the bottom of the cabinet, is this connector burnt or loose and not making good contact?
Contacts in cab appear to be good. There are two wires into both the + and - DC terminals in the BR. Is that an issue? Can I test voltage directly from the mutex from the transformer?
Quoted from GRUMPY:Yes, separate the 12 pin connector and check for voltage on each pair of wires.
White pair = 88.5 volts AC.
White/red pair = 26 volts AC
Blue/white pair = 13.5 volts AC
Black/yellow pair = 48 volts AC
The last set is 3 wires gray to gray/white = 9.7 volts AC
Gray/white to gray/green = 9.7 volts AC
So just to test something from here https://forums.arcade-museum.com/archive/index.php/t-106993.html I removed the connector pictured and then the bolts jumped to 16v at the TP3 and the big cap and the rectifier. Does this tell us something?
Quoted from GRUMPY:Yes, separate the 12 pin connector and check for voltage on each pair of wires.
White pair = 88.5 volts AC.
White/red pair = 26 volts AC
Blue/white pair = 13.5 volts AC
Black/yellow pair = 48 volts AC
The last set is 3 wires gray to gray/white = 9.7 volts AC
Gray/white to gray/green = 9.7 volts AC
Don't miss my post above, but here are my Transformer readings:
White pair = 94 volts AC.
White/red pair = 27 volts AC
Blue/white pair = 14 volts AC
Black/yellow pair = 50.5 volts AC
The last set is 3 wires gray to gray/white = 9.5 volts AC
Gray/white to gray/green = 9.5 volts AC
Quoted from GRUMPY:It tells me either the CPU or sound board(the other end of this cable) has a short and is dragging down the power supply or that the power supply cant supply enough current to maintain the correct voltage.
These look good. Reconnect molex connector.
Disconnect J-3 on the sound board to see if the short is on the CPU or sound board.
Ok I will check this out tomorrow. Thank you for your time man
Quoted from GRUMPY:It tells me either the CPU or sound board(the other end of this cable) has a short and is dragging down the power supply or that the power supply cant supply enough current to maintain the correct voltage.
These look good. Reconnect molex connector.
Disconnect J-3 on the sound board to see if the short is on the CPU or sound board.
Removing J3 and testing TP3 on the PSU is 9V. Does this mean the short is on the CPU?
I read somewhere online that if you set the DMM to diode mode, and attach black probe to ground, and then the red probe to the tabs of the transistors and it doesn't read '1', then it is shorted? Is this true? Because when I test Q6-Q9 & Q14-Q17 I get a reading > 100. No beeping though. All the others just display '1'.
Unfortunately, I cannot test voltage across diodes or transistors because of my crappy DMM. It's continuity settings only displays ohms.
Quoted from ChrisHibler:Maybe. There is an implication, but let's verify.
Replace J3 on the sound board.
Now remove 1J17 from the MPU.
Power on.
Take voltage reading.
Report back.
PS - If you really want to work on your game(s), purchase a good DMM and a logic probe.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
I actually have a logic probe
New readings after removing 1J17
BIG Honking Capacitor: 16v
PSU:
BR1 = 24VDC
TP1 = 3V
TP2 = 0V (Think this is a ground TP)
TP3 = 11V
TP4 = -12V
CPU:
+5 = 0V
+12 = 0V
+18 = 16V
Quoted from ChrisHibler:You are barking up the wrong tree.
The test you are performing might identify a shorted transistor, but that's not the short we are looking for.
We are looking for a short on a component that normally uses 12V and is pulling that power down.
Have you "diode checked" the bridge rectifier on the PS yet?
Procedure: http://www.pinwiki.com/wiki/index.php?title=General#Testing_a_Bridge_Rectifier
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
Yes, and it is a new BR. I cannot test voltages on unpowered stuff with my DMM. The diode mode is just 2000ohm + diode. But the procedure yields ~550 when testing the "odd ball" leg with the AC legs (Black probe on oddball, RED probe on the AC legs (one at a time), and ~1100 when testing odd ball leg with BLACK lead, and Adjacent DC leg with RED probe. When I place the RED lead on the oddball and test all legs, I get 1. So I believe this is all as expected.
Quoted from ChrisHibler:TP2 is ground.
You have the correct power at TP3 and TP4 being about 12/-12V.
TP1, if really 3V is a problem and your MPU should not be booting.
I can conclude that the bridge is fine since you have both plus and minus 12V.
Test TP1 again.
Black probe on TP2.
Red on TP1.
What does this read?
—
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info
1J17 disconnected, black probe on TP2 (on power supply), Red Probe on TP1 (Power Supply), 3V. My MPU isn't booting. When I turn machine on, the visor and the mouth just open and close. SOMETIMES I hear sloooow audio, I'm attributing this to the low voltage. Nothing works, door buttons etc. Non-responsive.
A couple weeks ago, it was working but continuously reset itself. Since then, I updated U25 to use Pinitechs NVRAM 6116, removed the battery pack, also R50 was broken in two. I replaced that. Don't know if any of this is related?
Here's something weird.. When I touch the RED probe to the + lead of the capacitor shown, and then the BLACK probe to TP2, I hear a "BONG" as if the system booted up and hear a faint audible buzzing. (like a super quiet computer). This is with 1J17 Disconnected. When I try with it connected, I don't get the BONG.
Quoted from ChrisHibler:I see that the board has been recapped.
The cap to the right of TP4 looks odd. Is it connected right?
By doing what you are doing, the 5V power is dipping and causing the sound board to reset. That’s a red herring.
Post a hires image of the entire PS.
—
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info
It’s an axial cap in place of one of the “tower” looking ones.
Quoted from GRUMPY:Next to the sticker is a thru hole filled with solder. Suck out the solder and install the cap in this hole.
K doing that now.
Quoted from ChrisHibler:I see that the board has been recapped.
The cap to the right of TP4 looks odd. Is it connected right?
By doing what you are doing, the 5V power is dipping and causing the sound board to reset. That’s a red herring.
Post a hires image of the entire PS.
—
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info
Am I crazy or are these soldering joints NOT supposed to be touching?? That’s the back of that 15 pin connector at the top of the power supply. When disconnected I get good voltage. Well.. That can't be the case because they all share a common trace...
Quoted from GRUMPY:These numbers are good but there wasn't any load because the molex connector was separated. Can you reinstall the power supply and connect all cables to all boards and recheck these numbers without disconnecting the molex connector this time.
Everything in backbox connected. Transformer molex connected.
White pair = 92 volts AC.
White/red pair = 26 volts AC
Blue/white pair = 13 volts AC
Black/yellow pair = 50 volts AC
The last set is 3 wires gray to gray/white = 9 volts AC
Gray/white to gray/green = 9 volts AC
Quoted from GRUMPY:With no load on, these readings are low. You have a poor connection somewhere causing low outputs on everything. I would look inside the metal box where the service outlet is for a bad connection. Unplug the machine first.
Nothing looked bad in the service box
Quoted from GRUMPY:How about a pic of the solder side.
E65F3A81-DEC8-48BD-8923-7309DA2FC741 (resized).jpeg
The BR looks like crap, but it has good conductivity
If my volts jump to normal levels on TP3 when I remove the 1J17 connector, then doesn't the issue lie on the MPU and not the PSU?
Quoted from ChrisHibler:Not necessarily.
The PS might not have enough "ass" to power the board.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
hmm, could the 2N6057 have anything to do with it?
Quoted from CactusJack:The 2N6057 is the pass regulator for the 5volts.
Take voltage readings on all three leads (Base, Collector, Emitter) and report back your findings.
Let me see if I can get in there lol
Quoted from CactusJack:The 2N6057 is the pass regulator for the 5volts.
Take voltage readings on all three leads (Base, Collector, Emitter) and report back your findings.
Everything connected I Get:
B = 5v
E = 3v
C = 8v
Shouldn't E be emitting 5v?
When I remove 1J17 I get:
B: 4V
E: 3V
C: 10V
Quoted from GRUMPY:These are too low to make 5 volts from. Should be 12.2-12.8 volts. Question of the day is why, is your BR bad, is the wafer connector or molex connector for the input AC burnt?
Is this the molex were taking about?
BA063478-E0FC-4370-94A4-7D9A0E403813 (resized).jpeg
F15A8380-A5D3-4CD0-9A0A-EE7303509DD6 (resized).jpeg
Reading Grey and Grey/White at this connector: 9.5V
Reading Grey/White and Grey Green at this connector: 9.5V
Quoted from ChrisHibler:Try this.
...connect that back up.
Disconnect the 15 pin header on the PS.
DMM set to DC volts (less than 20 if not an autoranging meter)
Clip your black lead to TP2 as you show in the picture.
Game on.
CAREFULLY probe pin 4 then pin 5 of the LM723 5VDC regulator.
The DC voltages there should be identical.
If they are not, then your LM723 has failed, and you really need to send the board out.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
Pins 4 and 5 read 5V
Quoted from ChrisHibler:Good. Nothing wrong with your 5V regulator.
So when you connect the MPU board power (1J17) and the 15 pin power header, test point 1 on the PS measures only 3V?
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
Well right now it feels like measuring 4V.
Quoted from ChrisHibler:Well then...best guess right now (and this has been along and winding thread) is that something on your MPU board is shorted.
Let's try one more thing.
Either remove the MPU board, or remove 1J17.
Meter on diode check.
Find a 7408 (lower left above the solenoid drives) or a 7402 (around the flipper power relay cube).
Red on lower left pin.
Black on upper right pin.
If any of the 5VDC components are shorted, the reading will be "abnormally low", i.e. not between .5 and .7.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
My DMM can’t test voltage between unpowered diodes. Just resistance.
Quoted from ChrisHibler:What make/model of meter do you have?
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
I have the one above, but I can go pick this up though if you think it will be useful in the long run:
https://www.homedepot.com/p/Klein-Tools-Auto-Ranging-Digital-Multi-Meter-MM400/206517333
Quoted from ChrisHibler:Yep. Go get it.
—
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact/
http://www.PinWiki.com - The new place for pinball repair info
ok, I tested p1 with the black probe and p8 with the red probe on U19 (7408) and got 1.26v
Quoted from ChrisHibler:Let's make sure we are doing this right.
A 7408 is a 14 pin IC.
New meter on diode check. That's the symbol that looks like this -|<-
You may have to press the SEL button. Make sure the meter is on diode check and not capacitance.
Red on pin 7.
Black on pin 14.
What does your meter say?
--
Chris Hibler - CARGPB #31
http://www.ChrisHiblerPinball.com/Contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
0.256v
ya.. my board is mounted upside down 
Quoted from LTG:You going to do anything about the connector burn in post 64's pictures ? ( connector and pins on the board )
LTG : )
Probably not.. are they more than a cosmetic issue?
Quoted from ChrisHibler:Good. The 10.5 is a bit low, but I see that often and it doesn't present a problem.
When you boot the game, do the LEDs on the MPU board behave like this?
http://www.pinwiki.com/wiki/index.php?title=Williams_System_9_-_11#Normal_Game_Boot_Behavior
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
So here are the full readings with the new meter:
PSU
TP1: 4.99v
TP3: 10.32v
TP4: 14.5v
CPU
+18v: 14.25v
+12v: 9.8v
+5v: 4.83v
ChrisHibler
Blanking is solid lit.
+5vdc is solid lit.
"Diagnostic LED" is not lit, nor flashing.
Quoted from ChrisHibler:OK...your MPU is not booting.
The voltages that you report are probably OK but I don't like the drop between the PS and the MPU.
I'd repin the 15-pin header on the PS (both male and female) and the 9-pin header on the MPU at 1J17 (again, both M and F).
But, that's not why your MPU isn't booting.
It should boot with those voltages.
Something else is preventing it from booting.
What could it be?
Any one of several dozen issues.
Remind me...did this MPU =ever= work for you or did you acquire it this way?
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
Yes, the game worked when I got it, but the top 2 displays are out (still are), and the game continued to reset (probably the low voltage).
This is the list of things I did:
Q79, Q78, R108, R109, R110, U50 Replaced
U25 (NVRAM updated)
Battery Pack Removed
R50 was broken, so I replaced.. (I actually broke this again to see if it was the issue, thanks for reminding me I need to fix it
BR1, BR3 replaced.
Cord End replaced
Don't know if this is a tell tale sign of anything, but I popped the CPU out and almost all the diodes are measuring Vs both directions with the exception of D1 and D2.. Is that normal? I haven't lifted any legs.
Quoted from ChrisHibler:I'm still here, but I'm at a loss of how to guide you further.
We've determined that your MPU board is not booting.
As mentioned, there are many reasons an MPU will not boot.
If I had the board in my shop, I'd...
...make sure the reset signal works
...make sure the clock signals are working
...ensure the ROM images are valid
...Install Leon's test ROM to test each PIA, address, and data bus operation.
Those steps would lead to a repair plan.
--
Chris Hibler - CARGPB #31
http://ChrisHiblerPinball.com/contact
http://www.PinWiki.com - The Place to go for Pinball Repair Info
Is there a guide in the wiki that explains how to test reset and clock signals? I have a logic probe and just snagged a Pc PSU from a thrift store I am installing to bench test.
Hey guys, quick question.. If I remove U25 all together, will the game boot and/or remember the current score? Or is that used for temporary storage too (current game). I have the board on the bench, and with that chip removed (I had installed NVRAM 6116), my diagnostic light is blinking. Before I plug it back in the machine to test, thought I'd ask here.
Thanks guys. I removed the U25 socket and reinstalled. The game is working great now without resets. I think this was a mixture of a lot of things, so wAs very hard to pinpoint. Thank you GRUMPY and
ChrisHibler for your very informative assistance. You guys have an excellent mental knowledge base and it’s a blessing that you share it with us
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