Capacitor-failure may produce a variety of defects. You appear to have more than one of them. From your description, the audio output sounds to have been affected. If you found capacitor goo under the PSU, power to the MLB may have been affected. The behaviour of the PSU may indicate either capacitor failure or TRKL circuit failure. The latter is not-at-all uncommon in the PSU that is used in IIcx, IIci and Quadra 700. Have you tried startup immediately after total removal of the PSU from the Mac for 10min. or so? Have you attempted the quick-flick mains-power trick? (Needs a power-board with a mains-rated switch.)
Board-washing may give temporary respite from the loss of capacitor efficiency, but it is not a recovery technique. It is a prelude to complete replacement of aluminium electrolytics with tantalum electrolytics as the only long-term cure. Our very own trag may be able to supply the values and quantities that you need. Even then, the larger electrolytics will need to be replaced with new aluminium electrolytics. You will have to conduct minute inspection of the board traces that were under the capacitor goo, and bridge any that were severed by corrosion.
The PSU may be suffering from leaking or defunct capacitors, but it is as least as likely that it is hobbled by the lack of 5V TRKL supply. This latter is a bias-diode problem, unrelated to capacitor action, and commoner in Astec supplies, but not unknown in the Delta PSUs. See whether you have the following voltages at the PSU connector to the MLB:
IIci-PSU pin-outs:
Pin Signal Description
1 +12V +12 volts
2 +5V +5 volts
3 +5V +5 volts
4 +5V +5 volts
5 GND Ground
6 GND Ground
7 GND Ground
8 -12V -12 volts
9 /PFW Power Fail Warning
10 +5V TRKL Supply voltage for power-on circuit.
TRKL must be 5V for startup, and be able to fall to <1V for software-controlled shutdown, so you will appreciate the centrality of its rôle. Post back as you eliminate/finger the usual suspects.
de
Board-washing may give temporary respite from the loss of capacitor efficiency, but it is not a recovery technique. It is a prelude to complete replacement of aluminium electrolytics with tantalum electrolytics as the only long-term cure. Our very own trag may be able to supply the values and quantities that you need. Even then, the larger electrolytics will need to be replaced with new aluminium electrolytics. You will have to conduct minute inspection of the board traces that were under the capacitor goo, and bridge any that were severed by corrosion.
The PSU may be suffering from leaking or defunct capacitors, but it is as least as likely that it is hobbled by the lack of 5V TRKL supply. This latter is a bias-diode problem, unrelated to capacitor action, and commoner in Astec supplies, but not unknown in the Delta PSUs. See whether you have the following voltages at the PSU connector to the MLB:
IIci-PSU pin-outs:
Pin Signal Description
1 +12V +12 volts
2 +5V +5 volts
3 +5V +5 volts
4 +5V +5 volts
5 GND Ground
6 GND Ground
7 GND Ground
8 -12V -12 volts
9 /PFW Power Fail Warning
10 +5V TRKL Supply voltage for power-on circuit.
TRKL must be 5V for startup, and be able to fall to <1V for software-controlled shutdown, so you will appreciate the centrality of its rôle. Post back as you eliminate/finger the usual suspects.
de