Hello everyone,
I'm looking for a bit of advice. I have an SE/30 board which I've recapped but I am having problems with further diagnosis on the above problem.
I'm aware of the dead mac scrolls and Larry's other book and have tried suggestions found around the web to replace the bourns resistor networks and SCSI chip.
Here's the story so far:
Recapped with tantalums. I've had them off a few times to check for shorts underneath and have gone through each adding solder mask where there's a risk.
Replaced all 3 resistor network chips with donor board parts.
Removed SCSI chip, Swim chip, Glue chip and UG12. Cleaned with IPA and re-soldered.
Completely replaced SCSI chip and UG12 with donor parts from another board.
Checked the reset line going to SCSI and SWIM. It's sat at 5V and drops to 0 when reset is pressed.
I've checked voltages at the power / video connector and all are present and within tolerance.
The whole board has been ultrasonically cleaned.
I think it's possibly a bad via or internal voltage missing. Any ideas where I could focus my attention? I guess checking voltages at each chip might be a good idea so I'll do that next. One thing I do have of note is when measuring resistance between +12 and -12, in one direction there is a low resistance value. Could possibly be related. I did try removing -12V via my ATX extender to see if it made any difference as that line only appears to head for the expansion slot but no luck.
If anyone has any experience with these beyond 'it's caps' my ears are open!
Many thanks in advance and happy to have finally registered here following decades of stalking
@techknight, particularly want to thank you. I've taken your advice in the past from previous posts and come good with a few other boards.
All the best,
Andrew
I'm looking for a bit of advice. I have an SE/30 board which I've recapped but I am having problems with further diagnosis on the above problem.
I'm aware of the dead mac scrolls and Larry's other book and have tried suggestions found around the web to replace the bourns resistor networks and SCSI chip.
Here's the story so far:
Recapped with tantalums. I've had them off a few times to check for shorts underneath and have gone through each adding solder mask where there's a risk.
Replaced all 3 resistor network chips with donor board parts.
Removed SCSI chip, Swim chip, Glue chip and UG12. Cleaned with IPA and re-soldered.
Completely replaced SCSI chip and UG12 with donor parts from another board.
Checked the reset line going to SCSI and SWIM. It's sat at 5V and drops to 0 when reset is pressed.
I've checked voltages at the power / video connector and all are present and within tolerance.
The whole board has been ultrasonically cleaned.
I think it's possibly a bad via or internal voltage missing. Any ideas where I could focus my attention? I guess checking voltages at each chip might be a good idea so I'll do that next. One thing I do have of note is when measuring resistance between +12 and -12, in one direction there is a low resistance value. Could possibly be related. I did try removing -12V via my ATX extender to see if it made any difference as that line only appears to head for the expansion slot but no luck.
If anyone has any experience with these beyond 'it's caps' my ears are open!
Many thanks in advance and happy to have finally registered here following decades of stalking
@techknight, particularly want to thank you. I've taken your advice in the past from previous posts and come good with a few other boards.
All the best,
Andrew