sound of sony trinitron broken

[Willem de Groot]

Hi, I've got a pretty old 27 inch Sony KV-E2911D trinitron television here,
which exhibits a strange behaviour.

- The soundvolume is depending on the brightness of the colours. IE, with a
totaly white screen, it sounds normal. With a dark screen there's no sound
at all.

- It is not dependant on the input channel. Both scart and cable input
channels have the same problem.

- We used to be able to increase the volume by increasing brightness.
However, this doesn't work anymore since the problem has gotten worse. The
first symptoms appeared 5 months ago.

- A side symptom is that it takes several minutes for the tv to warm up. Not
a problem for us, but maybe it's related? The sound used to play well before
we were able to see something, though.

So, should we buy a new one or is it worth taking this huge thing to a
repair shop? Or maybe we could fix it ourselves? There is a electrical
engineering student in our dorm, but unfortunately he has no experience with
tv's (or pretends :-).

Thanks,
Willem

[Jeroni Paul]

I would suspect bad capacitors at the power supply. You would need an ESR
meter to verify them. Or replace all those little caps at the power supply
regulation (they are more prone to fail than the big ones). Capacitors that
are warmed up while the TV is on are probably bad, and are the culprit.
Otherwise, it might be a bad regulator, but by the symphtoms you describe I
would look first at caps.

Be very careful opening a TV. There are dangerous electrical charges stored
by capacitors. Always check and discharge all the caps before touching
anything.

Good luck,
Jeroni Paul

"Willem de Groot" <gro...@cs.utwente.nl> told us:

[Jack Portier]

Leave the TV standing for 2 days before opening it up to allow the
capacitors to discharge. Then replace all the electrolytic capacitors (the
ones with polarity).

"Jeroni Paul" <JERON...@terra.es> wrote in message
news:lESL7.250272$zG3.7...@telenews.teleline.es...

[Wilco Verweij]

Jack Portier wrote:
>
> Leave the TV standing for 2 days before opening it up to allow the
> capacitors to discharge. Then replace all the electrolytic capacitors (the
> ones with polarity).

ALL of them? Have fun ;-)

Maybe its wiser to check on dry joints near the tuner and the HV
supply/flyback. It's not really necesary to wait 2 days before the tube
has discharged. Within one hour you can already work on it safely,
keeping in mind not to unplug the HV cable on the tube with unisolated
tools, eg. hands. And when working with bare hands, don't tough parts
with both of them.

ps.
Working on playing TV's can also be done safely, if you know what you're
doing. But although you may find a dry joint allot easier this way,
leave it up to a experienced person. (Maybe put that EL-guy on the
trial?)

Regards,

Wilco

[Wilco Verweij]

Jack Portier wrote:
>
> Leave the TV standing for 2 days before opening it up to allow the
> capacitors to discharge. Then replace all the electrolytic capacitors (the
> ones with polarity).