Toshiba 27" CF27D50 - Set will not power on - unplug for a few - symptom changes

[Doug]

When the power button is pushed - the red light comes on momentarily
then goes out. Once this happens, you get absolutely nothing when
pushing the button. Unplug the set for a few seconds and try again and
the red light again comes on momentarily then goes out. Set never
powers up at all. The first two times this happened - cycling power
like this brought the set up and it worked fine for a day or two. Now
it is permanently stuck in this cycle. Found service manual on-line
for the huge cost of $.03 plus S&H. To my surprise - was actually the
service manual with schematics, parts list and everything - just not
sure where to start.

Any help will be greatly appreciated!!

D

 

[Jerry G.]

Start by making sure that the power supply is working to specs. If it is in
the protect mode. Look for a short. It is common that the flyback and
horiz output transistor are bad. There may be many capacitors that are high
in ESR in your set. This may be the main cause of the failure.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
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When the power button is pushed - the red light comes on momentarily
then goes out. Once this happens, you get absolutely nothing when
pushing the button. Unplug the set for a few seconds and try again and
the red light again comes on momentarily then goes out. Set never
powers up at all. The first two times this happened - cycling power
like this brought the set up and it worked fine for a day or two. Now
it is permanently stuck in this cycle. Found service manual on-line
for the huge cost of $.03 plus S&H. To my surprise - was actually the
service manual with schematics, parts list and everything - just not
sure where to start.

Any help will be greatly appreciated!!

D

 

[Doug]

The HOT checks ok out of circuit. Not sure how to statically check the
flyback other than to make sure the windings aren't open. At first I
was thinking it was a faulty power fail safe circuit due to the fact
that if you unplug the set for a few seconds it seems to reset it.
Plan on going through this, the power section and the rest of the
horizontal drive section.


Regards,
D

 

[RonKZ650]

Look for a red 4.7uf capacitor near the switch mode power supply transformer.
If the set uses this part, it is open causing immediate shutdown due to
excessive power supply output.
Ron

 

[Jerry Greenberg]

The flyback may still be defective. It can have some shorted turns.
There may be some bad caps as well. The best test for a flyback is to
sub it. The multiplier may also be defective as well. I have seen many
like this!


jerry Greenberg