On Sat, 14 Jun 2008 11:58:40 -0400, Meat Plow
wrote:

On Sat, 14 Jun 2008 02:57:35 -0500, jakdedert wrote:

Meat Plow wrote:
On Sat, 14 Jun 2008 05:49:42 +0000, PaPaPeng wrote:

On Sat, 14 Jun 2008 00:49:57 -0400, Meat Plow
wrote:

The question here is
what kind of component makes a click when you use the remote to turn
the TV ON or OFF?
A relay.
There isn't one. That would have been the first component to suspect.

Well then you're hearing something snap, possible in the high voltage.


There are a lot of sets with various relays. It's certainly not out of
reason to hear a click. Some don't click, but at least one of the ones I
have does.


The OP claims there are no relays. I have my doubts.


Okay. Let us assume there is a relay. It clicks ON and it Clicks
OFF. This would indicate that the relay works. The question then is
which part of the circuitry causes it to click ON or OFF and why? How
does such a circuit work? It must be connected to the front panel
switch and the front panel IR remote singal detector and pass through
some circuitry before it connects to the relay.

The next question is a relay can only close a contact, that is
complete a conductor path, presumably to turn ON a circuit which
should then latch ON. That ON status lasts 5 seconds, a lifetime in
electronics. Then the relay clicks to OFF, an unlatch action. At
this point I can't figure out what is happening and why. Is there
such a thing as an undervoltage or overvoltage protection circuitry
that turns off the TV if the voltage (or some other condition) is not
met?

Everything in on a 12 inches by 14 inches motherboard. Thus there is a
high degree of IC integration that does not lend itself to component
repairs. The TV set worked great for something like 15 years. The
last time 5 years ago,there was an intermittent yet persistent
problem, was the spreading of scan lines on the top of the screen.
After many tries over a period of a few years I eventually got lucky
when a tool accidentally brushed a cable and I was able to reproduce
the problem. This allowed me to locate a practically invisible
separation of a pin donut on the MB. Reflowed that and the TV worked
even better then before. SONY PCBs do have a reputation for cold
solder separations with age.

Now back to the original problem of loss of second tier cable channels
that is blamed on the channel tuner. The TV set has an electronic
tuner. It doesn't have a bank of mechanical contacts to fail
selectively as in missing certain channels let alone a block of
channels. Is there such a thing as an electronic tuner that has
circuitry for blocks of channels, first tier, second tier, third tier
and so on. I would think access to those tier blocks are controlled
by the cable company. If the cable company cut off the second tier
channels, I should at least still have the channel number displayed on
the screen and maybe some "snow" not a totally blank black screen. I
don't have a conceptual tehcnical explanation for that either.