Tempest blows LM324 at K6 on aux

Paladin

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A new neighbor saw me working on a cabinet in my garage and asked if I'd take a look at a game they got at a garage sale. Turns out its a Tempest, so I said I'd look at it.

A visual check of the board showed some cold solder on the inter board pins, which I fixed then plugged it into my working upright to test. The LM324 at K6 on the aux board blew rather spectacularly when I turned it on.

Any ideas what to check would be appreciated. I didn't want to just socket and replace the amp, assuming something else must have caused the failure.
 
My board runs fine before and after the one that blew, but I'll check.
 
I would check for a solder bridge on the pins you reflowed. If it didn't blow before the reflow and did right after that's where I would start.
 
The neighbor bought it as non working, so I didn't test it in his cab.
The main PCB edge connector has been replaced with a solder type and the wires and tabs dont have shrink tube protection and have bumped against the back door to the point that several wires are making contact with each other.

I don't dare power on his cab until I replace or fix that connector. I don't know if it was ever powered on with the crossed contacts, if so it might very well have done some damage.
 
Probably damaged in the last cabinet and sealed the deal in yours. Socket the chip, toss another in, should be fine. That said, I would scrutinize the work on the home cabinets connector heavily, could have been a miswire. Alternatively if the replacement isn't keyed, it could have been plugged in backwards too. Proceed with caution and GL.

- Matt
 
Looks like Matt called it right. I finally got a chance to try the board again today after socketing in a new amp and it plays blind. Rather it plays blind because I don't have my monitor plugged in. I made an extension harness and will try his monitor with his board in my cab and see what I get.
I don't want to take a chance of frying my monitor before I give his a try first. It's times like this I wish I had a scope.
 
The board plays in my cabinet, but there's something wrong with the display output. I took a video, but haven't uploaded it yet. I swapped the aux board with my known good one with no change, so it's something on the main board.

I also tested the monitor and found it had deflection chatter and neck glow, but no HV. I took it apart and found R903, C905, Q901 and Q902 all blown in the HV cage. I just got done installing a Bob Roberts cap kit but haven't done the chassis mounted transistors yet. The monitor is the early version with the Atari protection board on stilts. I'll do the transistors tomorrow and cross my fingers.
 
When I first tried it several days ago I didn't hear any error tones. This time I did, 7 low and one high. The back door sheet indicates the location of the bad RAM. I reseated the interboard cable and cabinet harness, then performed the self test again and got the same tones. Odd that it didn't do it the first time. There's an E and R on the test screen, where there was only an E the first time I tested (E for NVRAM).

I didn't leave the game playing very long as I didn't want to damage the monitor that I just fixed (blown Q900 which caused my Bob Roberts replacement R903, Q901 and Q902 to blow. Q900 is not in Bob's kit and I didn't check it before powering up after the cap kit.)


With luck it's just a bad RAM - fingers crossed.
 
I had reflowed a couple questionable inter board pins earlier so I went ahead and did them all, no change though. I've got a couple sockets and one 2114 RAM on hand so I'll swap out the indicated chip and see where I am after that.

I also rebuilt the AR board and replaced the power cord that my neighbor ripped out while unloading it in my driveway. Still to do is replace the solder type edge connector someone installed without bothering to shrink wrap the tabs. They all got munched by the PCB pressing against the back door while the game was on its back.
 
Success!
I replaced the RAM at position L4 on the main board, as indicated by the audible tones and the game now plays! I can't believe I actually fixed it! I played a couple games from the blue to the yellow levels and didn't see any problems.

I still have the 'E' error for the NVRAM but I don't know if I'll bother to swap it out unless my neighbor wants me to since I'd have to order it.

Now that I've fixed his monitor and tested it with my game boards, fixed his game boards and tested them with my monitor and rebuilt his AR, I need to put all his parts into his cabinet. I still need to do a bit of cleaning and repin the harness.
This is what the harness connector looks like now:
 

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Just replaced the soldered edge connector with a new crimp pin one, replaced two blown fuses, a bad starter, 2 coin door bulbs placed the repaired boards into the cabinet and have a working Tempest.

I did notice some odd wavy vectors. Seems like only a short area of a line is effected, and doesn't seem to be tied to a specific area of the monitor. I saw it in the inside of the claw on the top of the triangle level, the I in Atari as well as occasionally when zooming to a new level. No idea if it's a monitor issue or board issue. One thing I did not do was to replace the big blue.
 

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