I bought an SE that was battery bombed so I worked and cleaned the board up and repaired what bad traces I found. I powered the Mac up and it had garbage on the screen in the form of faint checkers, but you could see a sad mac with some garbled error under it. I posted on the Low End Mac page and they all said it was RAM. I began cleaning the sockets (I had ultrasonic cleaned it after repairs were done) and cleaning the RAM and nothing really changed the error. I tries some RAM out of my IIci, but it didn't help. After many attempts to get it working, it suddenly stopped powering up at all. The fan would spin up, but there was not high voltage on the CRT. I went ahead and recapped the analog board and PSU, but nothing changed. I did notice the SCSI and CPU were getting burning hot, so I removed the SCSI chip (I had socked it previously) and the CPU heat went away, but still nothing. What else would I need to check at this point? Is the SCSI chip required for it to boot or do anything? Does the CRT require some signal from the logic board to turn on? Any help is greatly appreciated.
SE Woes
- Thread starter Devalis
- Start date
Check the analog board for failed solder joints. The heat causes the solder joints to crack, which looks like a ring inside of the solder joint, but sometimes the component leg can separate from the solder around it too. Best to just redo all of the solder joints on the analog board. The potentiometers also get oxidized and sometimes stop conducting properly, I'd suggest marking their position with a sharpie and hosing them down with deoxit gold and wiping them the full travel back and forth several times to get the oxidation out, then resetting them to their original position. If any black junk comes out of them, wipe that away before powering the analog board again.
If the SCSI chip and CPU were getting burning hot, they may be dead. The SCSI chip isn't required for booting, but the CPU definitely is. The SE may power on with a dead CPU, but display garbage on the screen since the video generation is handled elsewhere on the logic board IIRC.
I'd suggest checking the power supply voltages and seeing if they're correct. The SE PSU is subject to all sorts of weird problems from the heat and the corrosive and conductive glue that they splooge all over the board. I had to restuff my PSU with a TFX power supply because the original PSU had too many faults on it.
For RAM issues, make sure you have the RAM in the correct slots with the jumpers on the logic board set correctly. You also need to make sure that you're using the correct type of memory module. The SE is very intolerant of newer memory modules of the 4/5 or 2/3 chip type and require the older 8/9 chip types due to the internal ordering of the memory bits.
If the machine was battery bombed, it may still have hidden corrosion causing problems. You may want to check the logic board for shorts on the power rails and recheck any areas on the board that had battery electrolyte, this includes under ICs. If you didn't remove any ICs when cleaning the board, there may still be hidden corrosion and battery goo under them causing problems.
If the SCSI chip and CPU were getting burning hot, they may be dead. The SCSI chip isn't required for booting, but the CPU definitely is. The SE may power on with a dead CPU, but display garbage on the screen since the video generation is handled elsewhere on the logic board IIRC.
I'd suggest checking the power supply voltages and seeing if they're correct. The SE PSU is subject to all sorts of weird problems from the heat and the corrosive and conductive glue that they splooge all over the board. I had to restuff my PSU with a TFX power supply because the original PSU had too many faults on it.
For RAM issues, make sure you have the RAM in the correct slots with the jumpers on the logic board set correctly. You also need to make sure that you're using the correct type of memory module. The SE is very intolerant of newer memory modules of the 4/5 or 2/3 chip type and require the older 8/9 chip types due to the internal ordering of the memory bits.
If the machine was battery bombed, it may still have hidden corrosion causing problems. You may want to check the logic board for shorts on the power rails and recheck any areas on the board that had battery electrolyte, this includes under ICs. If you didn't remove any ICs when cleaning the board, there may still be hidden corrosion and battery goo under them causing problems.
