8032-SK repairs again - test-drb@ccmp.vtda.org

4 Sep 2001

On Sep 5,  1:44, Adrian Vickers wrote:

...
  Anyway, another PET related question: I've got 4
of the things now, and all
...
  of them suffer from wobbly screens to some extent; the
oldest (PET 2001) is
...
  the least affected somehow.... 
...
  Each PET has a huge electrolytic next to the
transformer marked "23000mF".
...
  Even given the can size, I assume they mean micro-F as
opposed to milli-F;
...
  but 23000uF seems to be impossible to get, should I
replace with a 22000uF
...
  or a 33000uF, both of which are readily available?

Given that the tolerance on electrolytics is often -20% +50%, I'd say the
22000?F should be fine.  It's a reservoir/smoothing capacitor, so 33000?F
would also be good.

...
  Also, do other non-electrolytic caps degrade - if so,
would it be worth
 replacing *all* the caps on old kit like this? 
The others won't fail the way electrolytics do.  As to the electrolytics,
many are probably OK and I'd not replace any apart than the ones I thought
were faulty.  I might replace a whole batch in an old switch-mode PSU if
one was failing, because experience suggests that in tightly-packed units,
with several caps clustered together, more than one starts to go at around
the same time.  Especially in SMPSUs that get hot.

...
  And finally: I bought a "Tip tinner/cleaner"
block, and now my soldering
 iron works a treat! 
One of those little round BIB cleaners?  Great!

-- 
Pete						Peter Turnbull
						Network Manager
						University of York