[rescue] Help me rescue my Sun Ultra 10 (2x)

[HP van Braam]

On Mon, 2025-12-15 at 10:45 -0500, Mouse via rescue wrote:
> > Okay, I have measured voltages on all of the big caps, and they all
> > have cro$
> 
> When you say "stable", what is that according to?

I compared to the voltage rails of the PSU. That is my PSU gives 5.05v
so I expect 5.05 or similar on 5v parts. On some SMD caps I see 4.7v,
while on the ones next to it 5,05. For instance. 

> A DC voltmeter may indicate a nice stable voltage even in the
> presence
> of insane levels of ripple, provided the ripple is high-frequency
> enough for the meter to not react to it (60Hz is usually plenty fast
> enough for meters to miss).

I will try to probe with a scope. I figured even if there was a lot of
ripple I wouldn't see like EXACTLY 1.90v on all 8 caps if one was bad.
But I guess they could just all be bad ;)

> Also, check the caps in the power supply, not just caps on the board.
> If the PS is putting out too much ripple, the board's own filtering
> may
> not be able to deal with all of it.

I tried with a different ATX power supply and that doesn't change
anything. If the PSUs are bad (which they might be!) then it's probably
not the cause of my current trouble.

> When doing the visual inspection, are you checking for bulging, or
> just
> leakage?  I've seen plenty of caps visibly bulging without any
> leakage
> apparent, but if you don't know to look for it it's easy to miss.

I was looking for bulging, or broken relief cuts in the top. I didn't
see any but maybe I don't really know what I'm looking for. That's very
possible. :)

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