Gottlieb system 80B 5v power supply! NEED MORE HELP!

[good_buddy83]

Can anyone tell me what components I need to swap on a Gottliebs Arean power supply to get it running again. Games turns on GIs, but not CPU, Sound or Display. Metered power supply board. 12-13v going in, only 0.4 to 0.8v going out. Nowhere near 5v. Seems simple, just wanna know what parts to swap.

 

[good_buddy83]

Re: Gottlieb system 80B 5v power supply.

Board in question.

 

[Menace]

Re: Gottlieb system 80B 5v power supply.

You should test the LM338 with your DMM in diode setting to see if it's good. I would also suggest looking at the trim pot, as these have high failure rates as well.

D

 

[good_buddy83]

Re: Gottlieb system 80B 5v power supply.

I'll try it tonight. Thanks.

 

[sylvain]

Re: Gottlieb system 80B 5v power supply.

Also check for cold/cracked solder joints at header pins, seen quite a few on those boards in the past.

- Sylvain.

 

[good_buddy83]

Re: Gottlieb system 80B 5v power supply.

No Dice!

Replaced the Voltage regulator LM 338K. Also replaced the pot.

Then I reflowed the solder at the connectors.

Then just to make sure, I checked for continuity everwhere with the DMD.

Here is what happened:

I screwed the board back in, flipped the machine on and tested voltages at connectors (disconnected from the board)

+15V ish going in. A little high, but unregulated so OK, plugged in the connector. tested output voltage at 4.5V ish. Tweaked the pot, max I could get was 4.85V. Thinking that was hopefully enough to run the game, I flipped the machine off, plugged in +5V output connector and crossed my fingers. Big nothing after waiting 20 seconds. OK, now I test voltages again. Only 0.9-1.5 Volts going out no matter what I tweak the pot to and yes rotating the pot changes the voltages accoringly, but out of range. I check voltage going in and it is stable at about 12.5V.

What gives!? I'm thinking maybe cap on the board, or resistor? Simple board and I am running out of options. Nothing looks cracked and everything connects.

One other question. This is a friends machine and I have the board removed. I only have williams WPC games at home. Can I test the board using the 12VU test point on the WPC driver board to see what I get a power supply to test at home? Obviously I would also ground the board, but let me know your thoughts. I don't want to wreck a WPC board trying to test a System 80 board. Help PLEASE!

 

[Menace]

If you want to bench test it, you can use any decent power supply that kicks out 12-15VDC. I wouldn't recommend using your WPC as the source for testing tho, just in case.

As for your issue, seems odd that after connecting the MPU it tanks the power supply. I will check my notes tonight when I'm home and add anything to the post that might help.

D

 

[good_buddy83]

I appreciate it. Thanks Manace. I agree seems weird. Seems like maybe symptoms of some kind of solder crack. I'm thinking, but I did meter everything. I was thinking of just jumpering the whole board to make sure, but that makes a mess.

 

[Menace]

If there is a crack or cold solder it should be fairly visible. Where you're still getting a voltage out, and it's adjustable by the trim pot, something else seems off...

I'd work towards getting this thing running good on the bench, before messing with anything else in the game.

D

 

[good_buddy83]

Swiped an old desktop computer power supply from work. Now I have a +12V and +5V power supply for bench testing WOO HOO!

We'll get this power board working one way or another.

 

[Menace]

Giddyup. You can also use that power supply to fire up the MPU, should you want to test it without the original.

D

 

[sylvain]

How's the AC ripple in the +15V supply going into the regulator ?
Perhaps the main filter cap in the cabinet is bad.
Or, bad pins in the connector to the +5V regulator board ?

Cheers,
- Sylvain.

 

[Luckydogg420]

I don't know if this will help, but has your game had all the ground mods done?

http://www.papinball.com/tips/sys80b_Ground_mods.html

It did wonders for my game.

 

[good_buddy83]

My current guess is ground mods to be done.

Had everything up and running on a bench test. 12 volts in, 5.1 volts out. No problems.

I'm thinking maybe ground mods, because I don't believe it is the boards fault.

 

[Menace]

Yep, connector issues in general not just the grounds are always an issue with sys80. Glad to hear you got it running on the bench tho.

D

 

[good_buddy83]

Yup Still need help.

I did the ground mods to the main board in the back box. I also Notice this machine already has a wi-Numf Cpu board, so I didn't do a ground mod for that board. Also, I don't really understand the ground mods to do in the cabinet. If someone can explain it to me it would be much appreciated.

I did find a burnt connector in the base of the cabinet. I changed the connector and oldy enough, voltage going into the board has now increased. I have 17.5Volts going in and about 2.5volts going out. This is no good. Also I noticed that with the machine switched on or off, I still have 17.5 volts going in. What gives?

I'm thinking either ground mods in the cabinet, or bridge and or resistors on the base of the cabinet. I think the problem is that too many volts are going to the power board that creatEs the +5volts. Hense, nothing is working. Let me know your thoughts. Thanks in advance.