(Topic ID: 170808)

Bally SDB was working until I replaced 2 transistors...

By DnDPins

7 years ago

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3 posts
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Latest reply 7 years ago by barakandl
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Linked Games

Mata Hari Bally, 1978

I had a SDB (originally from Harlem Globetrotters) in my Mata Hari and it worked for a while. Recently, my 1000 chime and Bottom Left Pop Bumper stopped working. Since I knew the issue was isolated to the SDB, I figured I would replace the transistor even though they tested good (tip 102s) and after doing so, the game fails to boot.

I replaced Q6 and Q8

I get one solid green light on the Alltek MPU and no boot. What could I have done by simply replacing these transistors which render the game in this position?

Thanks,
Dave

It's probably not your transistor replacement, more likely some spotty connectors that just happened to not reseat well when put back in, or a part already on its way out. First try reeseating connectors, 5v goes from SDB to MPU from J3. Has C23 ever been replaced on this SDB? If not, replace it.

When you had the board go in and out, connector may have been damaged.

Inspect the .100" header pin solder joints and crimps. Shine a light in and look for busted and blackened contacts. Tying C23 negative lead to master ground on driver board helps relieve stress on that connector. Bally isolated that ground and it was mistake.

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