Macintosh SE/30 Recap Issues

[mdanh2002]

Hi,

I just completed recapping an old Macintosh SE/30 I got from a friend. Before the recap, the Macintosh could boot up, but hung at a somewhat distorted grey screen, with no mouse cursor and no startup chime. After the recap and upon first boot, I could hear the startup chime and the grey screen is crisp with no distortion. I thought I have done well when I realized that the machine would actually hang at the grey screen without proceeding to ask for boot disk (the internal floppy drive as well as the hard disk drive have been removed). There is no mouse cursor on the screen and pressing the interrupt switch would generate the chime of death. Pressing the reset switch will just cause a reboot, followed by the startup chime, and then the machine would freeze again.

I think that the machine hangs at the RAM test phase. With 8MB of RAM I could expect it to take at most 15-30 seconds to complete the RAM test, but I waited for 5 minutes and nothing happened. Most online sources describe similar symptoms (hang at grey screen, but with mouse cursor) and say that this has to do with the network filter at the serial port or the SCSI chip. Mine is different as there is no cursor. Regardless I have checked the connectivity near the SCSI chip and the network filter and all seems to be good.

The 30-pin RAM modules tested good on another machine so I do not think it is DRAM issues.

Any ideas what else I can try? Many thanks.

 

[MacTech68]

The leaking caps can corrode tracks and eventually sever them. Tell tale signs are black areas instead of green on tracks and dark black appearance on the legs of ICs. Vigorous cleaning may more clearly reveal affected areas. It can be painful to find etched/broken tracks as some disappear underneath ICs, hiding where they go.

 

[Andy2k]

Also check the logic board. If it has a "maxwell" battery remove it immediately. They will burst and get battery acid on everything. This may have already happened unfortunately. If it's intact and a "maxwell" brand remove it to be safe. Like I said it may have leaked already and damaged the logic board. ( I know because the same thing happened to mine)

 

[havokalien]

Was the board cleaned before recap? If not washing in the dishwasher has worked wonders for me, bottom shelf even. Like mentioned before check the small traces as much as possible. Also the hard drives are known for dying so having floppies and a scsi2id is a great idea to use for years to come.

 

[mdanh2002]

Yes, I did clean the board thoroughly before recap. Anyway I already got the board working quite some time ago, after washing it with white vinegar and using isopropyl alcohol to clean off the corrosion underneath the chips.

I also removed the old battery and replaced it with a new one in a socket. For whatever reasons this board has a 3V Lithium battery pre-soldered. It wasn't leaking at all and still measured around 2.9V when I removed it.

The same board has been working well for three months with no strange behaviour observed.