Tempest board repair.

Have you by chance looked at the bridge rectifiers and wiring under the power brick? I know I overlooked mine and I had burnt up wiring and bad bridge rectifiers. I had a similar (but not exactly like yours) graphics issue on my tempest and this resolved those graphical glitches. Could have been a coincidence but the issue never returned for me after that.
 
Have you by chance looked at the bridge rectifiers and wiring under the power brick? I know I overlooked mine and I had burnt up wiring and bad bridge rectifiers. I had a similar (but not exactly like yours) graphics issue on my tempest and this resolved those graphical glitches. Could have been a coincidence but the issue never returned for me after that.

Appreciate the suggestion, but I'm using my known, good upright for the testing and when I plug in a known working board, everything is fine.

So I know it's not a power issue of any kind.

I'll hopefully have some more time tonight to work on this...

Thanks to all for the assists as I hopefully eventually figure this one out...

Jon
 
/LATCH3 signal appears to be present and OK. Probed the DVX signals/outputs, and they also look OK.

I went ahead and changed out the DAC08, but no change.

Oy...this one is being a pain :mad: .
 
OK, I finally have some more news to report on this board.

I've been probing all around over the past couple of weeks when I had the time (which was a bit less now that the holidays are over and I'm back at work ;) ). Can't say that I found anything new...

So I hunkered down with the lighted magnifying light and did a thorough scan of the board, both the solder and the component sides. I found some traces in the area of the RAM chips (N2, P2, etc.) on the solder side that were exposed and did look like they might have been scraped by something, tested them all, and they seemed to be OK. Nothing seemed to be broken, and none seem to be touching the other. But I cleaned them up anyway. This was a couple of days ago.

Then I had some time today and plugged the board in with the intent of doing some more probing, and voila! The board came up OK!

There was some bad bowing on the top, but I replaced the M1495 chip at A/B13 which took care of that, and now the game has a great picture and is playing perfectly.

Wish I could say for sure what fixed this puppy in the end, but I'm guessing it was the funky traces I found and cleaned up.

Hopefully, it will stay working, but I had it on for over an hour just now, and it seems fine.

Keeping my fingers crossed :) !

Jon
 
Nice. (fingers crossed) Visual inspection of a board is STEP #1. :)

I remember I had a Warlords board which was dead. Looked at the solderside and it had a big "scar" breaking several traces. Repaired those and it worked.

PCB storage mis-use is the #1 killer of PCBs today.
 
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