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I started measuring voltages across three electrolytic caps, and found that on two there was normal 5V, but on the middle one (C6), there was just 2V and slowly climbing. I let it plugged in for about 5 more minutes and the LEDs turned off and keyboard started to work normally. The voltage on C6...

This is a tantalum capacitor. Are there any markings whatsoever on this capacitor? Given the size, it could be 10uF 16V or similar, but you can't be sure.

I pulled out my trusty Apple Extended Keyboard II to test some vintage Macs. It has been stored for couple of years now. Sadly I discovered that it doesn't work, just all 3 LEDs are on, and also the connected ADB mouse does also not function. So any info on what I should do next? Could there be...

I know it is an old thread, but can you test the 8500 PSU in a PowerMac 8500? I am testing some 8500 power supplies that were known good, and I only own a 8100. The behavior is the same, if you press the power button it turns on for a second, then turns off. But if I use a proper 8100 power...

Just my 2 cents. Those Magnetek units need to be fully recapped in my experience as I had 2 of them that were completely blown, and majority of small caps were reading extremely high ESR / low capacitance. The always on 5V standby power supply also cooks the PCB and some of the capacitors...

Oh boy! Mine was also filthy, but nothing compared to this. I used some strong general purpose cleaner / degreaser and lots scrubbing with toothbrush, and rinsing with water jets. Wish you good luck. I think zener diodes do have markings on them, so it should not be too hard to replace them. Of...

R955A and B are both 180 ohms. If ZD1 and ZD2 are blown, then also both switching transistors are most likely blown...

Oh well. I remembered that I must have another 8100 PSU somewhere, and found it in the attic, and it is 100% identical, and working. So I opened it, and checked the component values. R955A and R955B are 180 ohms (0.125W). So I replaced those resistors with the right values, and the power supply...

I pulled out the exact same PSU I had lying under my bench for years. Back in 2015 it blew when the computer was powered on again after 15+ years. The last time I had it apart, I replaced some components on the 5V trickle supply as it was blown. Next I also discovered that one of the switching...

Which voltage rail of the PSU is shorted to ground? Are you sure all of the capacitors are oriented right way ? Is your motherboard known good (tested working)?

I had to recap a 8100 way back in 2015 when it was locking up/crashing in system. None of the caps were leaking, but they tested mostly out of tolerance (high ESR)

Vertical line is caused by failing LCD panel, so nothing will fix it, except replacing it with a different panel.

For much faster navigation and search I cleaned up (straightened) the scanned schematics that were provided on this forum, and did the OCR, so you can CMD+F (or CTR+F) the document. As I said, the Sawtooth mainboard is quite similar to the Digital Audio one, but of course there would be some...

And at last, I managed to repair the logic board. Long story short, it was the SI4467DY P-Channel MOSFET that shorted from gate to drain (in layman's terms: from control input to the power input). I used the PM G4 Digital Audio schematics as a reference (sadly they are not the best quality)...

I managed to repair the power supply, it had a shorted tiny diode on the primary side. The Mac now turns on, but shuts off after 2 seconds. No sounds or any other stuff is present. I am testing it just with CPU installed, and nothing else. PSU is tested OK, as I ran it for an hour with load...

Hey, In the attic I found a forgotten Mac that I stored there almost 20 years ago - back in 2008 or so. As the title says it is a PM G4 Sawtooth (AGP graphics). I would like to get it going. The case is in really nice condition, with no yellowing going on, but it has issues: 1. Power supply...

I think the main reason is the spring that loses tension after 30+ years of upwards pressure.

Yeah, but perhaps the OP can restore the images by reuploading them on this forum. 2021 isn't that far away still.

Cool, but the images are missing!

I am sure there is a way to reset the BMS, but probably needs some special software or even hardware. Having such a large value, I think the BMS probably has encountered integer overflow so its capacity has "rolled over". Value of 65483 (mAh) is very close to 65536 which is 2^16. There was a...