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(Topic ID: 222344)

MPU 100 Missing Capacitor

By oldschoolbob

5 years ago



Topic Stats

  • 9 posts
  • 5 Pinsiders participating
  • Latest reply 5 years ago by KenLayton
  • Topic is favorited by 1 Pinsider

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#1 5 years ago
OP
 
RAP

oldschoolbob

Pinside member

US Collinsville, IL

10y 111K 1,778 2

I’m working on a Stern Lectronamo. It wouldn’t boot in the game – missing 5 volts at the MPU. I have 5 volts at J4 so I pulled the board out and tested it on the bench. It booted fine. I need to replace the headers so I was looking it over so see what else needs to be done. That’s when I noticed that C80 is totally missing!

This board has been worked on before but I see it needs a lot of help. I just thought it was strange that it boots with missing parts.

Bob

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#2 5 years ago
 
???

KenLayton

In Memoriam

US Olympia, WA

12y 83,400 5,965

That's a picture of a Bally -17 MPU board. Capacitor C80 should be a .01 uf @ 100v.

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#3 5 years ago
OP
 
RAP

oldschoolbob

Pinside member

US Collinsville, IL

10y 111K 1,778 2

You mean it's NOT the original board? I'm shocked. Just kidding - seldom do I find a game with the original boards. But how can you tell it's Bally and not Stern?

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#4 5 years ago
 
ZAC

zacaj

RPC

US Rochester, NY

11y 158K 10,385 85 122 1

C80 missing is not a big deal, it's just a filter cap to clean up the 5v supply slightly. There's 8 of them around the board so if one fails not much happens.

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#5 5 years ago
 
AMS

barakandl

nvram.weebly.com

12y 132K 10,414

OP
Quoted from oldschoolbob:

But how can you tell it's Bally and not Stern?

M100 just look different. Traces with rounded edges, darker colored pcb and other stuff

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#6 5 years ago
 
ZAC

zacaj

RPC

US Rochester, NY

11y 158K 10,385 85 122 1

OP
Quoted from oldschoolbob:

You mean it's NOT the original board? I'm shocked. Just kidding - seldom do I find a game with the original boards. But how can you tell it's Bally and not Stern?

If it hadn't been sanded off to get at the corrosion there'd also be a part number on the bottom right

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#7 5 years ago
 
GSG

Dr_Dude

Pinside member

CA Ottawa, ON

7y 31,900 133 9

OP
Quoted from oldschoolbob:

You mean it's NOT the original board? I'm shocked. Just kidding - seldom do I find a game with the original boards. But how can you tell it's Bally and not Stern?

All the Bally boards are clearly drawn using CAD (Computer Aided Design) and all the traces are straight lines with angular turns and everything nicely lined-up. Stern actually stole the board-designs, re-drawing them by hand so you get swoopy/curvy traces instead. Because the designs were basically copied (and Stern did_ get sued by Bally over this!) almost all the boards are direct, drop-in compatible, the major exception being the MPU-200 vs. AS2518-35 (though these boards can easily be converted either direction).

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#8 5 years ago
 
???

KenLayton

In Memoriam

US Olympia, WA

12y 83,400 5,965

Stern boards are colored dark blue whereas Bally boards are green.

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#9 5 years ago
 
???

KenLayton

In Memoriam

US Olympia, WA

12y 83,400 5,965

Stern boards are colored dark blue whereas Bally boards are green.

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