(Topic ID: 220669)

Black Knight PS Getting Some Power W/Cab Power Switch Turned Off

By nerdygrrl

5 years ago


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  • 47 posts
  • 9 Pinsiders participating
  • Latest reply 5 years ago by barakandl
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#1 5 years ago

Update: If I flip the cab power switch to what seems like the on position (up) I get all of the volts, except for the 5V line. I hit the 12, the 28, the lamps, but no 5V.
I accidentally just tested the voltages with the switch flipped backwards and I now have 5V. I understand that the switch direction is somewhat meaningless. I just wanted to point out that regardless of switch position my 12v, 28v and lamp lines are getting juice on the PS. Only the 5V line is impacted by power switch position. I installed a new switch and nothing has changed. If the switch had been bypassed everything should be showing. Instead the switch is directly effecting the 5V line and only the 5V line. Any ideas?

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I picked up a BK last week that needed some TLC: https://pinside.com/pinball/forum/topic/nerdygrrl-gets-knighted

Yesterday I tested the PS and as you would expect, a good chunk of my caps were bad. My initial testing showed my 12V and lamp line were ok, but all of the other lines were below spec. My 5V was sitting at about 1.8 down the line.

I recapped the PS and that helped my solenoid line, but my 5V was still sitting at 1.8. I tested my BR and that tested fine, so I decided to swap the Q5 (even though original tested fine). I installed the new Q5 (lining up as should be), now when I test my 5V I get a higher initial reading, but the voltages quickly drop to 0. Almost like when you test a capacitor after powering it on and it drains.

I checked the new Q5 and it tests fine. Reflowed the connectors on the Q5, reinstalled, same deal, starts off higher in the 4's and 5's and quickly drops.

I went ahead and put the old Q5 in (which also tested fine), voltages are holding steady at 1.8V. The fuses are fine, and connector looks good and was reflowed.

I know there isn't a lot to this 5V line and I probably should just go ahead and swap out the BR, aside from that does anyone else have any suggestions? Has anyone seen this before?

Edited OK, let me clarify, I was calling Q5 (2N6059) a VR looks like the manuals refer to 2N6059 as VR.
So my new Q5 is acting weird. Old one holding strong at 1.8V

#2 5 years ago

Unplug the MPU, display, and driver and see if the voltage comes up. If so check for shorts on the other boards. voltage will get closer to zero when your probes get near the short.

#3 5 years ago

What’s a VR?

#4 5 years ago
Quoted from barakandl:

Unplug the MPU, display, and driver and see if the voltage comes up. If so check for shorts on the other boards. voltage will get closer to zero when your probes get near the short.

Everything is unplugged, this is just the main power going to the PS.

After doing some more reading I am wondering if it could be the 723PC?

Quoted from pintechev:

What’s a VR?

Voltage regulator.

#5 5 years ago

OK, let me clarify, I was calling Q5 (2N6059) a VR looks like the manuals refer to 2N6059 as VR.

So my new Q5 is acting weird. Old one holding strong at 1.8V

#6 5 years ago

Duh, VR. I knew that - thank you!

#7 5 years ago

OK, I swapped out the BR just to be safe and not much difference, bumped the readings up to around 2V

My guess is the IC (VR) is toast. I'll try and dig out a spec sheet in hopes of testing and verifying, but that's really all that is left on the line. I'm starting to think this game got plugged in, incorrectly.

Does anyone have a good source for a replacement IC? It looks like the more modern equiv is NTE923D, but that appears discontinued as well.

#8 5 years ago

Not sure if they're compatible replacements, but GPE has LM723CN: https://www.greatplainselectronics.com/proddetail.asp?prod=LM723CN

#9 5 years ago

I see plenty of them on eBay. Some are pulls, but I am sure you can find one that will work.

Marc

#10 5 years ago
Quoted from frunch:

Not sure if they're compatible replacements, but GPE has LM723CN: https://www.greatplainselectronics.com/proddetail.asp?prod=LM723CN

Derp, many thanks, I was looked up the more modern version at GPE and got nothing.

Quoted from pintechev:

I see plenty of them on eBay. Some are pulls, but I am sure you can find one that will work.
Marc

Looks like GPE has the 723. Going to drop them a line to verify.

I may get bold enough to hook a meter up to mine, but there isn't anything else left on that line.

#11 5 years ago

It’s too bad ezsbc doesn’t make a modern replacement yet. Their PSU regulators are amazing.

#12 5 years ago
Quoted from pintechev:

It’s too bad ezsbc doesn’t make a modern replacement yet. Their PSU regulators are amazing.

I'm just bummed that the IC is one part I overlooked when placing my order. I am jonesing to get this thing fired up. I guess I can get started on cleaning up the MPU now (ugh)

#13 5 years ago

Isn’t it always the one part you need that you never have in stock. I am fairly spoiled that I can drive to jameco and pick up anything they have in stock - I try to keep spares for stuff and always order more than I need. But Murphy...

#14 5 years ago

It looks like the 723CN that GPE has is an adjustable VR, I think that may be different than the 723PC. Dropped him a line to see.

Quoted from pintechev:

Isn’t it always the one part you need that you never have in stock. I am fairly spoiled that I can drive to jameco and pick up anything they have in stock - I try to keep spares for stuff and always order more than I need. But Murphy...

Oh definitely, this is my first System 7 so it's all new to me. I have a box of system 11 spare bits, many of which I have poached for this.

#15 5 years ago

I will check when I am home tonight to see if I have that part; I have tons of random crap so you never know.

#16 5 years ago
Quoted from pintechev:

I will check when I am home tonight to see if I have that part; I have tons of random crap so you never know.

Many thanks, much appreciated. I am sure Ed will respond. No big rush on it really as I just took the MPU and driver out and they are in need of serious love as well.

Definitely questioning the electrical engineering background of former owner...

#17 5 years ago
Quoted from nerdygrrl:

It looks like the 723CN that GPE has is an adjustable VR, I think that may be different than the 723PC. Dropped him a line to see.

Guys -- Same part, different manufacturer.
For this part, "P" and "N" in the manufacturer's suffix means 'Plastic DIP' type package.
The "C" in the suffix means 'commercial' temperature range of 0 to 70C.

#18 5 years ago

VERY important on the power supply -- did you change out the two small capacitors C7 and C8?

#19 5 years ago
Quoted from G-P-E:

Guys -- Same part, different manufacturer.
For this part, "P" and "N" in the manufacturer's suffix means 'Plastic DIP' type package.
The "C" in the suffix means 'commercial' temperature range of 0 to 70C.

You sir are awesome!

#20 5 years ago
Quoted from G-P-E:

VERY important on the power supply -- did you change out the two small capacitors C7 and C8?

I did, I grabbed a kit from Arcade Parts and Repair not realizing that you had the same 105 degree caps.

So C1, 3, 5, 7, 8, 9, and 12 were swapped. My BR and Q5 tested fine, but swapped in a new BR and a 2N6059 (which acted up).

The only thing that was not swapped was the IC. If I tested it right I grounded my black lead to the metal ground plate and red lead to the third pin down on the on right hand side of the IC and got a reading of about 1V. I believe it is supposed to be 3.

I ordered up some of the IC's from you earlier.

#21 5 years ago

I don’t have that IC. Sorry - glad you were able to order one!

#22 5 years ago
Quoted from pintechev:

I don’t have that IC. Sorry - glad you were able to order one!

I appreciate you taking the time to look!

1 week later
#23 5 years ago

OK, I got in the IC and installed it and I am still sitting in the 1.6-1.8 range on my 5v. At this stage everything has been swapped out component wise. I doubt it's the J6 pins as all test points are coming up short and the 12V is just fine.

What am I missing? New caps, new IC, new BR, the new Q5 was flaky, maybe the wiring or socket for that?

#24 5 years ago

I installed the "new" Q5 again, an upgraded 2N6059 and it's doing the same thing, starting at like 2V and dropping down to zero. I honestly don't know what it could be. My only thought that maybe I got the base and the emitter backwards. I am afraid to turn it around for fear that's not it and doing damage. Does anyne know what would happen if I got them reversed?

#25 5 years ago

If the pics I'm looking at are accurate, it appears the transistor would be difficult, if not impossible to install and screw in bc they slightly offset both legs to one side. It probably would have been a bit of a fight getting it installed backwards, since the mounting screw holes would be out of alignment. I don't have one of those in my stock, so i can't really say for sure though.

#26 5 years ago

Start by measuring from TP 4 (black Lead) to TP 3(red lead) and what DC voltage do you get?
Now set your meter to AC, measure from fuse 5 to fuse 6, and what AC voltage do you get, now measure the AC voltage on the other side of both fuse 5 and fuse 6.

#27 5 years ago

Can we get a pic or two of ps? Maybe someone will see something you haven't. Just a thought.
-Mike

#28 5 years ago

Some updates, I just tested R7, 8, 10 and 13 and all were in spec.

TP 1 is a flat 0, TP3 and 4 are =/- 14.69

D6 tested in circuit seems fine.

I will test the voltages form the fuses tomorrow. I'll post some pics in a couple of minutes. Thanks everyone.

#29 5 years ago

What I would be checking are the following points:

Power in to the LM723, pins 11 and 12 generated by C7/C8 which form a voltage doubler. I think this voltage is typically 18 to 22 V for an LM723.

Collector, Base and Emitter of the 6057/6059 pass transistor. This tells us if the 723 is providing enough voltage to the base for the output (emitter) to be around 5 and not 1.8-2.0VDC as you are getting. The 723 also has overcurrent shut down (sensed via R13) so like was mentioned, a short out on the other boards can cause it to run for a split second and then shut itself down.

Not sure if this williams schematic matches your board but it shows us where we want to see voltage readings.

wmsps (resized).JPGwmsps (resized).JPG
#30 5 years ago
Quoted from CactusJack:

What I would be checking are the following points:
Power in to the LM723, pins 11 and 12 generated by C7/C8 which form a voltage doubler. I think this voltage is typically 18 to 22 V for an LM723.
Collector, Base and Emitter of the 6057/6059 pass transistor. This tells us if the 723 is providing enough voltage to the base for the output (emitter) to be around 5 and not 1.8-2.0VDC as you are getting. The 723 also has overcurrent shut down (sensed via R13) so like was mentioned, a short out on the other boards can cause it to run for a split second and then shut itself down.
Not sure if this williams schematic matches your board but it shows us where we want to see voltage readings.

OK, I will test that tomorrow, when my brain is a bit more clear and my hand a bit more steady.

#31 5 years ago

Here are a couple of pics of the PS. I will try and grab a datasheet of the LM723 tomorrow so I can test the appropriate pins.

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#32 5 years ago
Quoted from CactusJack:

What I would be checking are the following points:
Power in to the LM723, pins 11 and 12 generated by C7/C8 which form a voltage doubler. I think this voltage is typically 18 to 22 V for an LM723.
Collector, Base and Emitter of the 6057/6059 pass transistor. This tells us if the 723 is providing enough voltage to the base for the output (emitter) to be around 5 and not 1.8-2.0VDC as you are getting. The 723 also has overcurrent shut down (sensed via R13) so like was mentioned, a short out on the other boards can cause it to run for a split second and then shut itself down.
Not sure if this williams schematic matches your board but it shows us where we want to see voltage readings.

OK, not sure if I tested this correctly, but with black lead on TP2 (ground) and red lead on target these are the readings I got:
LM237
Pin 12, 11 320.0 V
Pin 10 0V

*E 0V
*B 0V
*C 13.49

* I put my read lead onto the where the wires attach to the PCB

As per other boards, none are currently connected. I only have the PS connected.

#33 5 years ago

For pins 11 and 12 of the LM723, I am guessing you meant 32.0V? If so, that sounds good (2X 14.69V).

With the potential power of 13.49V at the collector, and 0 VDC at the base, you cannot expect there to be any output at the Emitter. So, it sounds to me like the LM723 is bad. Where did you get it? I can't imagine it is in shut down mode if you don't have anything else connected to it unless R13 is bad.

Did you check the ohms of R13 (0.12 ohms)? If it is open, the wrong value, or way out of range, it could cause the regulator to shut down due to sensing over current.

Also, try disconnecting J6 (the long one at the top of the regulator PCB) and recheck.

#34 5 years ago
Quoted from CactusJack:

For pins 11 and 12 of the LM723, I am guessing you meant 32.0V? If so, that sounds good (2X 14.69V).
With the potential power of 13.49V at the collector, and 0 VDC at the base, you cannot expect there to be any output at the Emitter. So, it sounds to me like the LM723 is bad. Where did you get it? I can't imagine it is in shut down mode if you don't have anything else connected to it unless R13 is bad.
Did you check the ohms of R13 (0.12 ohms)? If it is open, the wrong value, or way out of range, it could cause the regulator to shut down due to sensing over current.
Also, try disconnecting J6 (the long one at the top of the regulator PCB) and recheck.

I am getting .1 ohms on R13. I am using a Radio Shack DMM so I think that is the best I can do.

I don't know what is going on with my pin readings the DMM on auto was in the hundreds. I think there is a bad ground connection/connection. I am going to reflow that and see how it goes. Fingers crossed. All signs point to this.

#35 5 years ago

I GOT IT!!!!! Holy flipping hell, this makes no sense to me right now, but I got it. If I flip the switch to what seems like the on position (up) I get all of the volts, except for that 5V. I hit the 12, the 28, the lamps, but no 5V.

I accidentally just tested with the switch flipped backwards and I have 5V. I understand that the switch direction is somewhat meaningless. I just wanted to point out that plugged in and "off" I have some, but not all voltages hitting the PS??!!

What a head scratcher and time waster. It never occurred to me to flip the switch as I had most of my voltages. I guess I need to see how this line is coming into the switch or maybe just replace the switch.

#36 5 years ago

What switch are you speaking of? The power switch to the game? or a switch on your DVM?

Also, Auto Range meters are not the best to use. Are you seeing 320.0 VOLTS or is there a small mV symbol displayed? 320 Millivolts is not enough to power the LM723. Without it getting power, there won't be power to the base of the transistor and therefore, no output at the emitter.

In another thread, we discovered that when the line cord is wired wrong (black and white reversed), on a Gottlieb System 1 game, in the off position, there was still small amounts of current coming in to the power transformer. Not enough to power the game, but enough to make some feature lamp LEDs glow dimly. This is because when reversed, line power (Black) and earth ground (green) have a path to white via the EMI filter components in the line filter. Again, not enough to power normal things but it could supply a small amount of current which was enough to light some LEDs.

#37 5 years ago

The power switch to the game. In one position I get voltage off of the PS for the 12V, 28V and lamp line with no 5V. In the other I get the 5V, 12V, 28V, lamp...

I just checked the AC parallel cord coming in and the ribbed side is going to the white. Typically ribbed is neutral so that looks ok. The white with blue trace comes off of that and the white with red comes off of the black.

The molex coming off of the AC line filter that goes to the isolation transformer has been re-pinned. This could be the issue. I am going to try and look at that wiring diagram now.

I may swap out the power switch for good measure. I need to check its specs, I have some 6A, 125V toggles laying around that may fit the bill.

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#38 5 years ago

I just went pin by pin through the molex connector and that checks out. I guess I will swap out the toggle and go from there.

#39 5 years ago

Changed the switch out and I get the same thing. Power switch on one way I get 12V, 28V, lights. Flip it the other way I get 5V, 12V, 28V...

I'm stumped now, it doesn't make any sense at this stage. Time to walk away for a bit.

#40 5 years ago

I certainly don't understand what's happening. However, you stated "Isolation Transformer". Is there a second transformer besides the single factory transformer? Attached, snip of Black Knight power wiring.
wmsbkpw (resized).JPGwmsbkpw (resized).JPG
Also, here is a snip of the power supply from an F-14 Tomcat manual. Same circuit but this one has test voltages notated.

wmsps2 (resized).JPGwmsps2 (resized).JPG

#41 5 years ago
Quoted from CactusJack:

I certainly don't understand what's happening. However, you stated "Isolation Transformer". Is there a second transformer besides the single factory transformer? Attached, snip of Black Knight power wiring.

Also, here is a snip of the power supply from an F-14 Tomcat manual. Same circuit but this one has test voltages notated.

My apologies there is just the power transformer. I call it ISO out of bad habit from arcade stuff. Thanks for the F-14 schematic.

This doesn't make any sense to me. If the switch was bypassed all lines would get power. The fact that only the 5V line is impacted by the switch doesn't make any sense, yet here we are. I even had another local pinhead come over to verify. I think I am going to change the title of the thread and see if anyone has any idea re switch.

Many thanks for all of your help troubleshooting.

#42 5 years ago
Quoted from nerdygrrl:

I just checked the AC parallel cord coming in and the ribbed side is going to the white. Typically ribbed is neutral so that looks ok. The white with blue trace comes off of that and the white with red comes off of the black.

You got me , have you checked the house wiring on that outlet? Neutral /larger blade on left and hot is smaller blade on right while facing it, ground is obviously bottom center. Just a thought.
-Mike

#43 5 years ago
Quoted from Grizlyrig:

You got me , have you checked the house wiring on that outlet? Neutral /larger blade on left and hot is smaller blade on right while facing it, ground is obviously bottom center. Just a thought.
-Mike

Herm, good call. While I checked the wire, it didn't occur to me to check how the plug itself was attached. They could have wired that incorrectly. This is what happens when you get tunnel vision. Good to talk away.

I will take a look at that tomorrow or simply not bother and install the new AC cord I have and see how that plays out.

#44 5 years ago

I can't see how the switch can cause this issue. The problem is that both the 12v and 5v use the 9.5vac winding so I don't see how they can behave differently depending on the switch position. Can you check all of the transformer outputs with the switch in each position?

Edit: Not saying I wouldn't replace the switch just for grins.

#45 5 years ago
Quoted from terryb:

I can't see how the switch can cause this issue. The problem is that both the 12v and 5v use the 9.5vac winding so I don't see how they can behave differently depending on the switch position. Can you check all of the transformer outputs with the switch in each position?
Edit: Not saying I wouldn't replace the switch just for grins.

That is my weekend goal. Someone else mentioned getting something similar when he didn't have a load on the line. Not sure that makes sense, but nothing was hooked up so worth verifying.

#46 5 years ago
Quoted from nerdygrrl:

Someone else mentioned getting something similar when he didn't have a load on the line.

Load shouldn't make any difference. Look forward to seeing the numbers, I think it will tell us a lot.

#47 5 years ago
Quoted from nerdygrrl:

Changed the switch out and I get the same thing. Power switch on one way I get 12V, 28V, lights. Flip it the other way I get 5V, 12V, 28V...
I'm stumped now, it doesn't make any sense at this stage. Time to walk away for a bit.

I think the line cord voltage block or something near would have to be wired wrong.

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