theTedster
Member
Hiya. I've begun working on an SE/30 logic board that wouldn’t boot (no chime, no video output etc), clear signs of cap leakage near UE8 with mild damage to some traces under many of the caps - just exposed wire so I re-masked prior to recapping to make sure solder didn’t join things it shouldn’t.
Following that I now get a happy chime and a healthy Apple TechStep report, but the following video output:
Am hoping one of you folk will recognise this particular pattern and be able to suggest some further things for me to troubleshoot. Suspicion is damaged UE8 but also (maybe unrelated) weirdness with the bourns filters.
Troubleshooting so far:
1. Run TechStep tests as per:
ROMPACK A CPU Tests, Vol.1 1.1.1
ROM Pack Log ID# 11015
Test Name Description Runs Errs Other
PowrS Power Supply - - 5.00 Vdc
Verify CPU ID Verify CPU ID - - MacSE30
SCSI Term Powr SCSI Term Power - - 5.00 Vdc
SCSI Term Chk SCSI Term Check 1 -
ROMck ROM Checksum 1 -
BsRAM Base RAM (0-33K) 1 -
RAMsz RAM size - - 8MB
Address Test Address Bus Test 1 -
Data Data Bus Test 1 -
SIM1L SIMM 1 Left 1 -
SIM1R SIMM 1 Right 1 -
SIM2L SIMM 2 Left 1 -
SIM2R SIMM 2 Right 1 -
SIM3L SIMM 3 Left 1 -
SIM3R SIMM 3 Right 1 -
SIM4L SIMM 4 Left 1 -
SIM4R SIMM 4 Right 1 -
Video Video RAM Test 1 -
VIA VIA Test 1 -
Clock Clock Test 1 -
NonDestructive Parameter RAM 1 -
Destructive Parameter RAM 1 -
SCC SCC Test 1 -
SCSI SCSI Chip Test 1 -
SWIM SWIM/IWM Test 1 -
FPU FPU Test 1 -
Sound Sound Test 1 -
ADB ADB Test 1 -
** END OF LOG **
2. Swapped all removable chips (PALs, video ROM, RAM, ROM etc) in to a known working board, successfully.
3. Reflowed solder on J12. Didn't see any evidence of cold solder but it can't hurt.
4. Checked all three fuses.
5. Looked at the bourns filters with the following observations:
RP2:
between 45.3Ohms and 45.5Ohm’s across each pin pair
resistance to ground from pins 12 and 15. None of the others.
RP3:
45.3Ohms to 45.4Ohms across pairs.
Resistance on pins 12, 13, 14, and 15. But not the other pins.
Now the above is obviously not normal but is it likely the bourns filters have failed, or does this indicate a short elsewhere? I had thought if any of the caps went bad in a filter then the readings would essentially cascade across all pins, or is that not always the case? I have no spare filters at present that I can swap in to test.. but would a failing filter cause video issues anyway? The SCC tested out fine in TechStep too..
On initial pre-cap inspection I did note cap damage on LS166 (as per below image) which I believe is UE8, a video mux. After ultrasonic it cleaned up okay but does still look dull. Is it likely that's dead? Or should I try reflowing the solder?
Before Ultrasonic clean:
After clean:
Following that I now get a happy chime and a healthy Apple TechStep report, but the following video output:
Am hoping one of you folk will recognise this particular pattern and be able to suggest some further things for me to troubleshoot. Suspicion is damaged UE8 but also (maybe unrelated) weirdness with the bourns filters.
Troubleshooting so far:
1. Run TechStep tests as per:
ROMPACK A CPU Tests, Vol.1 1.1.1
ROM Pack Log ID# 11015
Test Name Description Runs Errs Other
PowrS Power Supply - - 5.00 Vdc
Verify CPU ID Verify CPU ID - - MacSE30
SCSI Term Powr SCSI Term Power - - 5.00 Vdc
SCSI Term Chk SCSI Term Check 1 -
ROMck ROM Checksum 1 -
BsRAM Base RAM (0-33K) 1 -
RAMsz RAM size - - 8MB
Address Test Address Bus Test 1 -
Data Data Bus Test 1 -
SIM1L SIMM 1 Left 1 -
SIM1R SIMM 1 Right 1 -
SIM2L SIMM 2 Left 1 -
SIM2R SIMM 2 Right 1 -
SIM3L SIMM 3 Left 1 -
SIM3R SIMM 3 Right 1 -
SIM4L SIMM 4 Left 1 -
SIM4R SIMM 4 Right 1 -
Video Video RAM Test 1 -
VIA VIA Test 1 -
Clock Clock Test 1 -
NonDestructive Parameter RAM 1 -
Destructive Parameter RAM 1 -
SCC SCC Test 1 -
SCSI SCSI Chip Test 1 -
SWIM SWIM/IWM Test 1 -
FPU FPU Test 1 -
Sound Sound Test 1 -
ADB ADB Test 1 -
** END OF LOG **
2. Swapped all removable chips (PALs, video ROM, RAM, ROM etc) in to a known working board, successfully.
3. Reflowed solder on J12. Didn't see any evidence of cold solder but it can't hurt.
4. Checked all three fuses.
5. Looked at the bourns filters with the following observations:
RP2:
between 45.3Ohms and 45.5Ohm’s across each pin pair
resistance to ground from pins 12 and 15. None of the others.
RP3:
45.3Ohms to 45.4Ohms across pairs.
Resistance on pins 12, 13, 14, and 15. But not the other pins.
Now the above is obviously not normal but is it likely the bourns filters have failed, or does this indicate a short elsewhere? I had thought if any of the caps went bad in a filter then the readings would essentially cascade across all pins, or is that not always the case? I have no spare filters at present that I can swap in to test.. but would a failing filter cause video issues anyway? The SCC tested out fine in TechStep too..
On initial pre-cap inspection I did note cap damage on LS166 (as per below image) which I believe is UE8, a video mux. After ultrasonic it cleaned up okay but does still look dull. Is it likely that's dead? Or should I try reflowing the solder?
Before Ultrasonic clean:
After clean:
