(Topic ID: 261801)

Stars MPU won't boot with PF lamp connectors plugged in

By QuietEarp

4 years ago


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  • 15 posts
  • 2 Pinsiders participating
  • Latest reply 4 years ago by QuietEarp
  • Topic is favorited by 1 Pinsider

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Linked Games

  • Stars Stern Electronics, 1978

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#1 4 years ago

Hi,

I was doing some work on my Stars. I had it playing well for a few weeks. Then it wasn't getting 12 volts DC on the rectifier board (TP3). I corrected that issue (Bridge Rectifier) and now the game will not boot up. It gave me 4 flashes. I found that if I unplugged J1 on the MPU the game would boot. J1 feeds the lamp driver board and displays.

I find that if I connect J1 on the MPU but unplug connectors J1 and J3 on the lamp driver which feed the insert lights on the playfield, the game boots up. If either of these are connected to the lamp driver board, I only get 4 flashes on the MPU.

Where should I be looking from here? What is causing this?

I have a Weebly MPU and the rest is vintage.

Thanks!

#2 4 years ago

An update. I swapped in the Lamp Driver Board from my Mata Hari and the game worked fine.

Stars LDB in Mata Hari works fine.

So I swap the boards back to their original games and everything in Stars works fine?!

What could this mean? Repin board and connectors J1 and J3? Seems weird that these connectors would cause booting problems as they only drive the controlled lamps?

I would still like to know why that happened because I didn't like that and it could happen again. Any ideas?

#4 4 years ago
Quoted from Quench:

If by chance when you were diagnosing your 12 volt issue did you disconnect J4 from the lamp driver board and accidentally reinstall it off by one pin or upside down?

I don't see how I could have as it has the key in the connector housing.

Thanks for the suggestion though!

#5 4 years ago

Update!

When I did the whole board swap thing between Mata Hari and Stars I did not fasten the board with the screw so the boards were floating.

Game works fine with lamp driver board floating. When I screw the lamp board in creating a solid grounding path with all lamp board connectors plugged in the game does not boot.

If the board is screwed in and the connectors to the PF lamps are unplugged (J1 and J3) the game does boot up.

Any thoughts with this new info?

#7 4 years ago

If J1 or J3 is plugged in the game does not get past 4 flashes. Both must be unplugged for game to boot.

Disconnecting MPU connectors J2 and J3 does not make any difference. I also tried only disconnecting one of them at a time and there was no difference.

Earth Braid is connected to cabinet.

#9 4 years ago

Quench, thank you for your help! I have seen you in these types of threads diagnosing things and the help you provide is very much appreciated.

Now the game seems to not boot when the grounding screw is in the lamp board no matter if J1 or J3 is plugged in on the lamp board. This was definitely different yesterday.

a) yes, all feature lamps work properly when lamp board is not screwed down

b) 0 volts

c) Game boots

d) 4 flashes on MPU

e) 4 flashes on MPU

#11 4 years ago

(F) 4 flashes only
(G) 4 flashes only
(B) 0 volts AC and 0 volts DC

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#13 4 years ago

About 3230 ohms on each of them. One (R75) tested at 4300 ohms. Measured to the ground test point on the LDB.

#15 4 years ago

So I have been playing Stars without the LDB screwed in and it has been fine. Today I was going to try all the new recommendations so I screwed the screw back in grounding the LDB and the game booted fine. I will post again if this starts to reoccur.

I will post some answers to your questions though because for all I know this will start happening again!

I do not believe I am counting any initial flicker as a flash.

I didn't work on anything else besides the rectifier board at that time though I got the machine un functioning and it has only had about 60 games on it since I got it going.

No short behind LDB.

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