22 Aug
2015
22 Aug
'15
6:43 p.m.
Oooh, didn't know about the diodes. Are there any specific ones that you
think should be replaced no matter what? If not, are there any tests you
would recommend?
Regards
Rob
On 22 August 2015 at 19:10, tony duell <ard at p850ug1.demon.co.uk> wrote:
Should I leave well enough alone, or is there preventative maintenance
that
should be done? For instance, should capacitors
be proactively replaced.
In
general, I'm thinking about things that, if
they fail catastrophically,
would cause collateral damage.
The main part you want to protect is the flyback transformer. It is very
hard to
get a good replacement now. Flybacks can just fail, but failure can be
caused
by defective diodes and capactors on the video PCB. Look at the schematics
for
your video board (there are at least 3 versions) for half-wave rectifier
circuits that
produce the CRT and video stage supply voltages from the flyback. You
might want
to check or replace those diodes and caps.
A VT100 and models derived from it (VT105, etc) has an SMPSU. Defective
capacitors
on that can kill the chopper transistor, but that is in not impossible to
replace.
-tony