Arfa Daily wrote:
"z" wrote in message
ups.com...

ian field wrote:
"z" wrote in message
ps.com...

boardjunkie wrote:
z wrote:
Anyone knows which circuit in a tv set is resposible for the
brief delay between switching the set on and the appearance
of an image on the screen?

Tube cathodes heating up via the filament (heater).

O.k. so what conclusion could one draw if this warm up
period is taking very long (15 minures)?


One possible cause is high value start up resistors in the PSU going very
high, this can mean the PSU doesn't start immediately but can be got
going
by a random mains spike.

Some designs use the charging current through a small high voltage
electrolytic to kick-start the PSU.

Another capacitor related problem is whichever electrolytic holds the PSU
error feedback voltage goes high ESR giving a false excess voltage error
voltage - this causes the PSU to idle at too low O/P to start the set -
in
both capacitor related faults, the capacitor in question gradually warms
up
causing the ESR to decrease, at some point the capacitor may then get
close
enough to normal operation for the set to start.

O.k, this is useful, I will spray some freezer spray to see if I can
locate a faulty electrolytic or resistor. Which area of the chasis
should I look at? The power supply area is it near where the ht cable
which goes into the crt (the suction pad at the other end), there seems
to be one very big electrolitic there rated at 400volts and quite a few

smaller ones near it. The other circuits are for example the one on
the neck of the tube, and several circuits are inside metal boxes
(like the tuner).


Based on what you have just said, I would have to venture the opinion that
you do not have sufficient experience to be working on dangerous items such
as a TV set with a switch mode power supply, and any further encouragement
that we might give you to carry on trying to get to the bottom of your
problem, is likely to result in injury. In view of the fact that you get
sound immediately, it is unlikely that the problem is one of the psu being
slow to start. Please just take it to a reputable repair shop.

Arfa

The idea of this ng is for hobbists to try to fix, seems to
me you are forgetting the reason for this ng. I am not
going to do anything stupid, all I want to do is spray a bit
of freezer spray to locate this problem, I am not even going
to touch any connection, so what can go wrong? I will not
take it to a repair shop, if I can't fix it I will simply buy a new
one.

One more question:
I am considering subscription to the following database
http://www.euras.com/repair_tips_1/P..._Panasonic.htm
however mt model is tx-w28r3, would this be the same as the one
above?