I'm working on getting a Star Gazer I justed picked up playing. Game had a new RottenDog rectifier board in it but the J3 plug was missing, just loose wires hanging there. Previous owner said he couldn't get it working and never got to play it.

I verified the recitifer board connections and fixed the J3 plug. The MPU is showing a solid red LED and I haven't gotten as far to set it up on the workbench for further diagnosis. However, I did check all the test point voltages and they are in spec on the rectifier board, soleniod driver board, and MPU board except for these two:

- SDB: TP5 = 14.82VDC (should be 11.9 +/- 1.4VDC)
- MPU: TP2 = 14.0 VDC (should be 11.9 +/- 1.4VDC)

Would this 1.5VDC overage be enough to cause problems? Seems unlikely...

It looks like battery acid damage.

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Yeah, it looks pretty limited.

I found another reason why it wouldn't be workng when I pulled the 5101 chip to assess the socket.
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Which components do you think I should replace? I'm thinking the components along the bottom to the left side of the 5101 socket, that are at or below the bottom half of the 5101 socket. There is also a pretty suspect capacitor in the middle of that group with blackened leads.

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Yeah, I looked at them really closely under magnification and decided to only replace a few of them. I haven't even had time to review the plentiful information on Pinside re: battery leakage restoration yet, but do I need to remove the solder mask over the areas that are lifted/bubbled from the battery damage, while keeping the traces intact?

Thanks for the advice. Actually, I'm pretty handy with a soldering iron so don't anticpate any issues replacing the socket. I was thinking of using the "acid bath/toilet bowl cleaner" technique on the bottom of the board as well to neutralize the alkalinity. Just not sure I really want to try to peel the masking off but I guess will see what comes off when I wire brush it.

Okay, I finished cleaning it up and am trying to disgnose a locked on led. Documented my test results in my Star Gazer thread: https://pinside.com/pinball/forum/topic/star-gazer-rising#post-3556378

Any advice is always appreciated.

Vid, left you a response on my SG thread re: MPU issues.

I initially had my J1 plug on the power board mis-wired and was feeding 7v into the 12v line and vis-a-versa. Of course the SDB failed to output 5v in that configuration.

Once I corrected the plug wiring R50 on the SDB burned up immediately.

The rest of the SDB looks pristine, though it has original caps.

So besides the caps I need to order a replacement for R50. Schematic says it's a 4.7ohm resistor, but no wattage rating is specified. Which wattage should I get?

Also, though everything looks fine, should I go ahead and order replacements for the other components on the same circuit?

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Thanks for the reply.

I noticed that C24 looks a little messed up, could that possibly cause the r50 to fail?

EDIT: I should be able to test the 5v regulator by removing the burnt R50 and measuring the vdc from its positive mounting hole, correct? I'll try that before I replace it.

The voltage regulator is fairly expensive, any tips on where to pick one up?

Thanks again!

Better late than never, eh Vid?