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IIcx Power Woes
- Thread starter mcdermd
- Start date
uniserver
Well-known member
double check this cap and the traces,
and check for debris and solder bridges around the legs of the rom chips and the CPU legs and other chip legs, take out the ram and closely inspect the slots for debris.
also pull the logic board out and inspect the bottom, make sure you didn't accidentally pop off any surface mount components.
and check for debris and solder bridges around the legs of the rom chips and the CPU legs and other chip legs, take out the ram and closely inspect the slots for debris.
also pull the logic board out and inspect the bottom, make sure you didn't accidentally pop off any surface mount components.
Juror22
Well-known member
1) Double check this cap and the traces - traces appear intact, re-soldered cap to makes sure it was ok
2) Check for debris and solder bridges around the legs of the rom chips, CPU legs and other chip legs - there are a few chips that had some corrosion on the legs, I re-flowed the solder in those locations
3) Take out the ram and closely inspect the slots for debris - I saw nothing under the magnifying glass...
4) Pull the logic board out and inspect the bottom, making sure you didn't accidentally pop off any surface mount components. - checked, only one appears to not be installed (C17) on the bottom of the board, could someone confirm whether this is supposed to be there?
Looked at every trace across the board and did not see anything suspicious. Also checked the fuses - all ok
I will continue looking...
2) Check for debris and solder bridges around the legs of the rom chips, CPU legs and other chip legs - there are a few chips that had some corrosion on the legs, I re-flowed the solder in those locations
3) Take out the ram and closely inspect the slots for debris - I saw nothing under the magnifying glass...
4) Pull the logic board out and inspect the bottom, making sure you didn't accidentally pop off any surface mount components. - checked, only one appears to not be installed (C17) on the bottom of the board, could someone confirm whether this is supposed to be there?
Looked at every trace across the board and did not see anything suspicious. Also checked the fuses - all ok
I will continue looking...
Juror22
Well-known member
Thanks, uniserver, I appreciate your other suggestions and that you took the time to check your board for the absence of C17. I did not replace those capacitors, when I originally recapped the board, but when I was going through this thread and I read your previous message about replacing those 4 larger caps (mine did not seem bad either), I immediately changed those out on mine as well, thinking that was an issue for me as well. I am still re-checking traces and trying to understand the startup circuit that was posted earlier.
uniserver
Well-known member
my roms are soldered, would you happen to have a ROM simm from a SE/30
you can (disconnect the rom jumper first) right near the soldered roms, pop the se/30 rom in the rom simm slot,
and try it, not sure if it will work, but its worth a shot.
I have herd of peoples rom's going bad, not often but on this forum all you hear about usually is the strange odd issues people have.
sometimes people dishwasher their logic board and it makes it worse because they did not try it off completely,
then they power it up , and that is when some chips get cooked. or the water causes some really bad rust under bad caps or more corrosion.
or like you said the startup circuit maybe one of those chips cooked, if you you carefully follow some of the traces from some of the rom chips you will see they go all they way(under all the ram slots) over to the power up circuit (noticed this last night)
you can (disconnect the rom jumper first) right near the soldered roms, pop the se/30 rom in the rom simm slot,
and try it, not sure if it will work, but its worth a shot.
I have herd of peoples rom's going bad, not often but on this forum all you hear about usually is the strange odd issues people have.
sometimes people dishwasher their logic board and it makes it worse because they did not try it off completely,
then they power it up , and that is when some chips get cooked. or the water causes some really bad rust under bad caps or more corrosion.
or like you said the startup circuit maybe one of those chips cooked, if you you carefully follow some of the traces from some of the rom chips you will see they go all they way(under all the ram slots) over to the power up circuit (noticed this last night)
Juror22
Well-known member
In going through the startup circuits with a continuity tester, I found one of the traces that was bad (it looks fine visually but does not conduct). It comes from R42 on the back of the board through to the front just above F3 and then along the pos. side of the row of capacitors, ending just above C9... I soldered on a jumper wire and now it powers up without any buttons (shortly after you plug it in, it just comes up), still no chime and no boot, but I am going to take it as progress. I'll need to continue following the traces, maybe there is one more that is messed up in the switch circuit.
I did not do the dishwasher thing (I know there are those that swear by it, but I like controlling what gets washed), but I did wash it and hopefully it was fully dried out before I tried to start it, but that was some time ago.
I have an SE/30 that needs analog board work, so I will steal the ROM from that and try it out. I assume that the jumper that you referred to is W1, correct?
Thanks again for your help and suggestions.
I did not do the dishwasher thing (I know there are those that swear by it, but I like controlling what gets washed), but I did wash it and hopefully it was fully dried out before I tried to start it, but that was some time ago.
I have an SE/30 that needs analog board work, so I will steal the ROM from that and try it out. I assume that the jumper that you referred to is W1, correct?
Thanks again for your help and suggestions.
Juror22
Well-known member
I tried the ROM swap trick and it powered up the same - still no boot, chime etc. I have checked all the traces that were listed in the Gamba IIcx startup circuit, and except for the one trace that I fixed, the rest of them checked out OK (for continuity). I appreciate everyone's time and comments (especially Uniserver's). I did make some progress and although I don't have a booting computer yet, I have a better starting point for the next time I take it up.
Thanks!
Thanks!
Juror22
Well-known member
About two weeks ago, someone nearby (1-1/2 hours, that's not too far for Vintage Mac parts is it?) had a IIcx and IIci board posted on Craig's list for $15, so I thought that might be better than spinning my wheels with this, so I picked them up, cleaned and re-capped the IIci board (I rescued the caps from the IIcx that was in the previous posts), carefully cut out an extra hole in the back of my cx case (for the onboard video - I had mixed feelings about that, but utility won out) and booted (with chime) into 7.5 on the IIci-x. The floppy needs to be refurbished, but otherwise it is in perfect shape. :beige:
The extra IIcx board that I picked up?
I booted it up to make sure that it worked as well and then I un-capped it. (I will re-cap it later, when I have time) ... for now I won't have to worry about the caps leaking.
One thing about that IIcx board, it was VERY easy to remove the caps, very little heat and very light twisting removed them. It was almost like the solder, holding the caps on, had dry-rotted, since they were almost falling off.
The extra IIcx board that I picked up?
I booted it up to make sure that it worked as well and then I un-capped it. (I will re-cap it later, when I have time) ... for now I won't have to worry about the caps leaking.
One thing about that IIcx board, it was VERY easy to remove the caps, very little heat and very light twisting removed them. It was almost like the solder, holding the caps on, had dry-rotted, since they were almost falling off.
mcdermd
Well-known member
I figure I should put this anecdote in here for posterity.
I was stumped that after recapping a IIcx board for someone. It would not power on via ADB. The power switch on-board worked fine and it ran very stably. All of the keys on the keyboard worked and the mouse was fine. The only thing that was not working was the power-on via ADB keyboard.
Pin 2 is the pin for soft power and to send the power button signal, it shorts to the pin 4 ground in the 4-pin ADB mini DIN. All of the ADB pins on the two ADB ports are linked in series then to the rest of the logic board. After close inspection, I saw that the trace linking pin 2 between the ADB connectors was rotten. My guess is that the leaking capacitor electrolyte oozed it's way between the two ports and ate away at the small trace.
I was stumped that after recapping a IIcx board for someone. It would not power on via ADB. The power switch on-board worked fine and it ran very stably. All of the keys on the keyboard worked and the mouse was fine. The only thing that was not working was the power-on via ADB keyboard.
Pin 2 is the pin for soft power and to send the power button signal, it shorts to the pin 4 ground in the 4-pin ADB mini DIN. All of the ADB pins on the two ADB ports are linked in series then to the rest of the logic board. After close inspection, I saw that the trace linking pin 2 between the ADB connectors was rotten. My guess is that the leaking capacitor electrolyte oozed it's way between the two ports and ate away at the small trace.
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