Recapped SE/30 logic board suddenly died (no video, dark screen, no boot chime, speaker click)

[tt]

I did some searching, but I thought I would check to see if this is a categorized failure mode for troubleshooting. I had recapped this logic board, and it had been running well. It was an SE/30 that I took to Mactoberfest last year and had been a reliable machine. One night while running it, the screen went dark, and I could no longer boot up the machine. I thought the warmer-than-usual weather might have been a factor. Here are the symptoms:

• No sound is produced other than a speaker click/pop.
• The screen is completely dark and doesn't show any signs of life.
• The floppy drive makes a brief half-second noise as usual.
• Pressing reset does nothing.

I isolated the problem to the logic board: I swapped in a known good logic board into the "Mactoberfest" machine, and it looks like the PSUs are fine since it works. I moved the bad logic board to another good system, and it doesn't work.

I tried cleaning it with some contact cleaner around the capacitors, but it still doesn't work. I checked and reflowed all the replaced caps (I used polymer caps), but it still doesn't work. I swapped around the RAM SIMMs. I unseated and reseated all the socketed chips. I swapped the ROM SIMM.

So far, I gathered that UE8 may need to be replaced, but does it cause the system to be almost completely dead or just knock out the video? Anything else I should check?

 

[Byrd]

Sounds like power I’d check the connector and cable going to the analogue board and motherboard. That harness, male and female pins can become marginal/corroded, reflow the underside of the motherboard around this edge connector

 

[bibilit]

I had this problem once, was a shorted capacitor near the main connector.

 

[tt]

Sounds like power I’d check the connector and cable going to the analogue board and motherboard. That harness, male and female pins can become marginal/corroded, reflow the underside of the motherboard around this edge connector

Thanks for the tip! I sucked out the old solder for the connector pins on the bottom and added new solder and it started working again. Before that, the connector solder joints looked fine and I tried applying some pressure on the cable harness but still no signs of life.

 

[Byrd]

Great to hear! I have a SE/30 board with this very problem, re soldering the connector worked but also needed to thoroughly clean the machine pins before it was fully reliable again. One day I'll replace the entire wiring harness with new and thicker gauge wires.