21 Mar
2014
21 Mar
'14
5:18 p.m.
It really depends on the age, but absolutely not lineair.I have a
fernseh video monitor from around 1955 still working fawlessly without
any work on it done. but machiens from around 1991 and up are
dramatically bad. als som areas round 1978-1980 are suspect. i have old
macintoshes from 1989 in perfect condition, but all of the ones made
after 1991 with leakage and shorts. really all. mac II no problem, Mac
IIfx all bad. that is what i mean.
On 21-03-14 22:11, Tony Duell wrote:
--
Met vriendelijke Groet,
Simon Claessen
drukknop.nl
check the powersupply capacitors, and all othe capacitors. they can
short or have taken a completely wong value over the years. changing
them all is a good idea.
can somebody please expalin why I rarely see capacitor failure, for all I
work on machines a lot older than this Osborne?
More seriously, I ahve had capacitors fail, but not that many. I have
never had to re-cap an entire machine.
In this case I would, indeed, start by checkig nthe power supply outputs
-- votlage and ripple. If there is a problem, then I would find out what
it is. It might wwell be a capacitor, but I wouldn't change it until I
knew. It might also be a bad connection oxidised pins, etc), a failed IC
(bit-rot in an EPROM, RAM failur, etc). Or a dozen other htings.
My 'first rule of repair' is not to change anything until you know what
the problem is....
-tony