Rev3 resurrection? Help requested!

[chiark]

I have a rev3 500, one of the early ones made in W Germany with embossed case and C= keyboard. Problem is, it doesn't work

Black screen, no power light. After 30 seconds the drive light may come on. AFter a further few seconds, the power light may flash.

Caps lock lights and goes out. Pressing on/off toggles for 6 times before it stays on, suggesting the buffer isn't being cleared by CPU IIRC.

I've changed every socketed chip inside for known good: no joy.
No hot RAM chips.

have put an oscilloscope on TP1 and TP2, and get nothing, not a sausage, so I suspect the crystal has gone. Putting oscilloscope on a leg of the crystal shows nothing meaningful either...

Any advice for debugging, and has anyone heard of a crystal failing on Rev3?

[amigasith]

Do you perhaps have another known working PSU that you could try?

[chiark]

Yes, should have mentioned that: PSU is known good, and is an AT PSU modified for Amiga use. For completeness have also tried 2 other known good.

[amigasith]

Hmm... okay. Although everybody says an oscillator failure is an extremely rare thing to happen, I have a dead one for my Blizzard 1260.

It's a spare oscillator - can't remember it's frequency right now - that I use for running the Blizzy at stock speed or close to stock speed and it stopped working without any prior signs of trouble. The last time I tried it, I removed the current one - that slightly overclocks the Blizzy - replaced it with the spare one and it simply didn't work. Since the frequency of the spare one is lower than the current one, I'm pretty sure it's not an overclocking issue.

So in summary, I think it's pretty seldom that it happens, but it can definitely happen.

[chiark]

Right, I'll try to change it. I've tested by probing TP1 and TP2, and I think one should be 28MHz right out of the osc, but there's nothing...