ironborn65
Well-known member
Dear all,
I was able to fix a couple of 68k Macs (LC III, IISI), I was on my way for a LC. The board was not in bad conditions, a couple of capacitors had sign of early leaking.
I replaced all of them but with some differences respect the original spec
- all the 47uf 16v were replaced with tantalum 47uf 20v
- the 100uf 6.3v were replaced with a 100uf 15v non SMD electrolyte
- all the 10uf 16v were replaced with tantalum 10uf 20v
- 1uf 50v with 1uf 50v non SMD electrolyte
I did the same kind of placement with my LC III and it was just fine, increasing the voltage shall not be an issue, on the contrary AFAIK
This is what I got at boot:
- happy chime
- yellow LED blink on the SCSI2SD
- the screen becomes uniformly grey, a quick off-on and grey again
- the SCSI2SD blinks irregularly as it does for any regular boot
- the LED stop blinking with a System typical error beep sound, as it does when an extension is wrong, and this shall be the case here
- the screen remains grey
Apparently it boots just fine, there is an issue with the video.
The configuration is the following:
- the PSU provides a stable voltage
- brand new battery
- The motherboard has no additional VRAM
- I tried with additional RAM SIMM (same issue)
- No other cards are present
- The monitor is working, so do the cable, no adapted is used, but just in case I tried with another cable and monitor (same issue)
See the picture of the motherboard (some capacitors are not perfectly inlined but the connections are fine).
I see the following options:
- a faulty VRAM (I do not have an oscilloscope)
- the capacitor not being 100% of the right spec
- something I do not know
Can someone provide directions, ideas, help in general?
thanks you all for reading all this
I wish you all a better 2020 (it should be easy)
PF
I was able to fix a couple of 68k Macs (LC III, IISI), I was on my way for a LC. The board was not in bad conditions, a couple of capacitors had sign of early leaking.
I replaced all of them but with some differences respect the original spec
- all the 47uf 16v were replaced with tantalum 47uf 20v
- the 100uf 6.3v were replaced with a 100uf 15v non SMD electrolyte
- all the 10uf 16v were replaced with tantalum 10uf 20v
- 1uf 50v with 1uf 50v non SMD electrolyte
I did the same kind of placement with my LC III and it was just fine, increasing the voltage shall not be an issue, on the contrary AFAIK
This is what I got at boot:
- happy chime
- yellow LED blink on the SCSI2SD
- the screen becomes uniformly grey, a quick off-on and grey again
- the SCSI2SD blinks irregularly as it does for any regular boot
- the LED stop blinking with a System typical error beep sound, as it does when an extension is wrong, and this shall be the case here
- the screen remains grey
Apparently it boots just fine, there is an issue with the video.
The configuration is the following:
- the PSU provides a stable voltage
- brand new battery
- The motherboard has no additional VRAM
- I tried with additional RAM SIMM (same issue)
- No other cards are present
- The monitor is working, so do the cable, no adapted is used, but just in case I tried with another cable and monitor (same issue)
See the picture of the motherboard (some capacitors are not perfectly inlined but the connections are fine).
I see the following options:
- a faulty VRAM (I do not have an oscilloscope)
- the capacitor not being 100% of the right spec
- something I do not know
Can someone provide directions, ideas, help in general?
thanks you all for reading all this
I wish you all a better 2020 (it should be easy)
PF
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