22 Feb
2015
22 Feb
'15
5:43 p.m.
On Sun, 22 Feb 2015, Robert Jarratt wrote:
Well...I tend to look at replacing aluminum electrolytic capacitors as
more of a maintenance or preventive maintenance thing vs a repair issue.
If they are old and/or you have ripple, replace them and get that
potential cause out of the way first and be done with it.
Were you able to find the correct axial mount parts for the 22uF, 4.7uF,
and 75uF capacitors? I did a quick search through some of my past projects
for compatible parts and managed to work up a short list of part numbers.
From: cctalk [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Tothwolf
Ah. That explains it then. I was beginning to wonder if the printset had a
typo and it was supposed to be a 250V rated part. I didn't see any
indication in in the parts manifest that it was a NP part either, but
perhaps I overlooked it. Are any of the others NP parts?
Is C441 really 10uF 25V? That is what both the
parts list and schematic
show, but even as old as a VT101 is, I wouldn't think a standard 10uF
25V part would be in an 18mm diameter can.
Yes it is. I have it right in front of me. It is a non-polarised
capacitor that looks like an electrolytic. I've had
this discussion with several people recently, but why bother
even attempting to reform the capacitors on this particular board? If
you are going to desolder them anyway, why not just replace them and be
done with it? From the high resolution photo, the original axial mount
parts at C439 and C437 have already been replaced and almost all of
these parts are cheap and very easy to obtain. The only exception I can
see is C437, which is a 75uF 6V part. Even with that one, you can still
get 75uF axial mount parts from Vishay in 25V and 50V which would
probably fit the pad layout just fine.
I suppose I could do that, but I do like to try to find the actual
problem if I possibly can, and keep as much original as possible, and it
helps me to learn about the circuits too. Perhaps I should just replace
and be done with it, which saves me storing up trouble for the future. I
have the parts ready but just want to see if I can find the problem
first.