"David B." wrote in
:


"Jim Yanik" wrote in message
4...
"David B." wrote in
:

I have a sony KV34 HS 510 tv that wont power on . The protector
circuit kicks out and stanby light flashes 7 times.
Does anyone knowwhat would cause the above issue and how I could fix
it?

Thanks Dave




probably bad electrolytic caps.(ESR)

--
Jim Yanik
jyanik
at
localnet
dot com

Thanks for the replies. The tv has a DA-4 chassis. I'm not a tech but
have done some work on guitar tube amps. Tube circuitry is pretty
straight forward makes tracing, reading voltages etc easy work . The
only real trouble shooting I've done on ic's involved switches and
solder joints. Dave




modern TVs use high frequency switching power supplies that depend on low-
ESR 105degF electrolytic caps.When the caps ESR climbs,they load supply
lines and eventually,the PS control IC current limits,or goes into "burst"
mode,where it tries to start,current limits,then retries to start
repeatedly.
Sometimes,you get lucky and the bad cap(s) are discolored or swollen,easily
spotted.Other times,you need an ESR meter like the Dick Smith meter.

Now,the bad caps can be on the secondary side,or they can be on the primary
side(or both!),particularly the "housekeeping" supply for the PS controller
IC.

Replacement caps -must- be low-ESR 105DegF,or they don't last very long.

To learn about your TV's power supply,find the power supply control IC(it
will be near the big line-input electrolytic caps,or near a heatsinked
transistor),then Google the datasheet for it.It can tell you a lot.

Sam Goldwasser also has a nice site for troubleshooting.

--
Jim Yanik
jyanik
at
localnet
dot com