22 Jul
2015
22 Jul
'15
5:31 a.m.
This thread has gone on for a while and I think we all get the points
here, but one other consideration - how will removing and replacing a
component damage the board? Damage the board and it's game over. One
should always take the overall board's ability to handle replacement.
With the board in mind, I avoid any part replacements and try to keep
them to what is proven necessary only.
On Wed, Jul 22, 2015 at 8:18 AM, tony duell <ard at p850ug1.demon.co.uk> wrote:
That, actually, is the wrong question to ask. You should ask 'How do you
know if these old capacitors are working as well as the brand-new replacements
will'.
--
Bill
vintagecomputer.net
They
reliably do what they're supposed to do.
You didn't answer the question. How do you know those aluminum
electrolytic capacitors are functioning just as good as they did when they
were new? Unless you've tested them out of circuit, you simply cannot make that assertion.
I think he did answer it. If the unit is operating correctly then the capacitors must be
sufficiently good at that time for that unit.
Now, whether they will go on working is something that is very hard to tell. But that
applies
to every other component in the unit. An IC might work find now and suffer bond-out wire
failure later on the same day.
Just like the NiCd and SLA batteries I mentioned,
aluminum electrolytic
capacitors by their very electrochemical nature degrade as they age and as
they are used. You cannot claim that a 20-30 year aluminum electrolytic
Semiconductors also degrade both with time and use. I would think a 30-year-old
3 terminal regulator IC was also beyond its design life. So do you replace those
'anyway'? The damage done if one those fails is likely to greatly exceed the
damage
done if a capacitor fails.
Do you replace all EPROMs in case they develop bit-rot (They are most likely way
beyond their design life by now)?
-tony