18 Jan
2006
18 Jan
'06
3:10 a.m.
At 12:27 AM 1/17/06 +0000, you wrote:
I think both of those would apply without having to state the obvious.
At 01:04 PM 1/13/06 -0700, you wrote:
This is a constant flamewar in the UK vintage radio magazines...
I would be careful shotgunning parts. Firstly that you don't introduce
more faults (either by using unsuitable capacitors or mis-connecing
them). Secondly that you don't cause problems by changing a capacitor in
a timing cirucit and having to re-align things).
I have found in a number of supplies the front panel adjustable pots
open up or the wiper go south. This will make the output go to max.
Another problem is small electrolytic caps in the voltage control
circuit going bad. Often, blindly shotgunning all the small caps will
make things work for another 15 years (sorry Tony...).
Don't apologize. There's nothing wrong with that approach. If one cap has
failed, it's mostly likely that the other's aren't far behind.
And of course you do need to be able to trace the fault 'properly' if
changing the capacitors doens't fix it.
My expeireince with old HP instruments (mostly from their decktop
calculators) is that capacitors are not a major source of problems.
That usually true of HP gear but it's a BIG problem in Tektronix and
other brands. I've found that I can't leave a Tektronix scope of the 465
vintage powered off for very long without them developing shorted
capacitors. I had a Tek 465 that I only used occasionally and everytime
that I turned it on (several months apart) it had a new capacitor problem.
That went on for over two years till I finally gave up on it and found a
newer scope (Tek 2445). I suppose the difference is due to the different
type/brand of caps that HP and Tektronix used.
FWIW I like the Tek scopes better than HP scopes but the HPs hold up
better.
Joe