I had to join to consult the 68k experts so I can help somebody relive some old memories.
This Quadra last ran just fine in 2015. It was fully functional then and was left in the garage.
Last week, I opened the Mac and about six surface-mount electrolytic capacitors were rolling around. I thoroughly washed with alcohol and scrubbed away any trace of the goo. The original Lithium battery was intact and looked new! I pitched it anyway.
I desoldered the remaining capacitors and cleaned all of the pads thoroughly and re-tinned them. I soldered tantalum capacitors in and I've checked their orientation probably ten times now. Most importantly, I checked that each capacitor leg was indeed making contact with the vias on the board. All of them check out.
I thoroughly removed the flux, rinsed thoroughly with alcohol, blew every drop of liquid out, and let it sit overnight and through the next day. Once I pressed power, I heard the bong and got a "?". Turns out that no matter what I do, the SCSI drives won't do anything more than wake up and then standby. They're not receiving any seek instructions. HDD, CD, even an external SCSI with internal termination wouldn't boot or seek.
I created a bootable floppy of the System 7 disk tools and hey! It boots! As soon as I put the floppy in, it gives me a happy Mac and boots into the utility. The graphics seem odd but I don't know if I can attribute that to the 10-switch adapter to HD-15 VGA monitor. I'm running at 66hz RGB 480 but it is very green and seems misaligned vertically. What sync mode and resolution etc. should be best to use when testing with this adapter? My monitor is a ViewSonic CRT from around 2001.
Pressing reset does nothing in any scenario. Pressing Interrupt within the disk tools bootup causes the crash but the crash doesn't load completely with any crash code etc. if that makes sense. Just an empty white window that appears.
Things I've tried:
With and without the new PRAM battery installed.
ADB keyboard with every thinkable key combination on start.
With and without any SCSI devices plugged in.
With and without any RAM installed and with each RAM stick individually and tested in each slot.
Does anybody know if a PSU could cause this? Could somebody with a similar PSU tell me what Ohms you get from all of the power pins to the PSU case (ground)? The pinout is like red, red, red, black, black, black, black, yellow blue. When it is running, all the voltages seem OK except that the black (I assume ground, right? They Ohm out to about 0ohm to ground with my meter) gives me about 2-5microvolts when the computer is running.
Here's a clue. If I run it for a while, it will eventually get less and less successful with the boot process. It will go from booting, to just reading the floppy long enough to get a happy Mac, to not reading the floppy at all nor giving a question mark, to finally not giving a cursor. If I let it sit for 15-20 minutes, it will succeed on the first try. When it is successful, artifacts or weird random pixels will appear as glitches here and there. Sometimes it will actually just freeze completely.
Pretty at a loss here. I'll try to get pics of my screen and board but hopefully this sounds like something somebody has experienced. I have never really troubleshooted with 68K so please forgive my utter ignorance with the terminology and conventions.
Thanks for reading and here's hoping I get this together in time for a very happy Christmas.
This Quadra last ran just fine in 2015. It was fully functional then and was left in the garage.
Last week, I opened the Mac and about six surface-mount electrolytic capacitors were rolling around. I thoroughly washed with alcohol and scrubbed away any trace of the goo. The original Lithium battery was intact and looked new! I pitched it anyway.
I desoldered the remaining capacitors and cleaned all of the pads thoroughly and re-tinned them. I soldered tantalum capacitors in and I've checked their orientation probably ten times now. Most importantly, I checked that each capacitor leg was indeed making contact with the vias on the board. All of them check out.
I thoroughly removed the flux, rinsed thoroughly with alcohol, blew every drop of liquid out, and let it sit overnight and through the next day. Once I pressed power, I heard the bong and got a "?". Turns out that no matter what I do, the SCSI drives won't do anything more than wake up and then standby. They're not receiving any seek instructions. HDD, CD, even an external SCSI with internal termination wouldn't boot or seek.
I created a bootable floppy of the System 7 disk tools and hey! It boots! As soon as I put the floppy in, it gives me a happy Mac and boots into the utility. The graphics seem odd but I don't know if I can attribute that to the 10-switch adapter to HD-15 VGA monitor. I'm running at 66hz RGB 480 but it is very green and seems misaligned vertically. What sync mode and resolution etc. should be best to use when testing with this adapter? My monitor is a ViewSonic CRT from around 2001.
Pressing reset does nothing in any scenario. Pressing Interrupt within the disk tools bootup causes the crash but the crash doesn't load completely with any crash code etc. if that makes sense. Just an empty white window that appears.
Things I've tried:
With and without the new PRAM battery installed.
ADB keyboard with every thinkable key combination on start.
With and without any SCSI devices plugged in.
With and without any RAM installed and with each RAM stick individually and tested in each slot.
Does anybody know if a PSU could cause this? Could somebody with a similar PSU tell me what Ohms you get from all of the power pins to the PSU case (ground)? The pinout is like red, red, red, black, black, black, black, yellow blue. When it is running, all the voltages seem OK except that the black (I assume ground, right? They Ohm out to about 0ohm to ground with my meter) gives me about 2-5microvolts when the computer is running.
Here's a clue. If I run it for a while, it will eventually get less and less successful with the boot process. It will go from booting, to just reading the floppy long enough to get a happy Mac, to not reading the floppy at all nor giving a question mark, to finally not giving a cursor. If I let it sit for 15-20 minutes, it will succeed on the first try. When it is successful, artifacts or weird random pixels will appear as glitches here and there. Sometimes it will actually just freeze completely.
Pretty at a loss here. I'll try to get pics of my screen and board but hopefully this sounds like something somebody has experienced. I have never really troubleshooted with 68K so please forgive my utter ignorance with the terminology and conventions.
Thanks for reading and here's hoping I get this together in time for a very happy Christmas.