Dear Sir,
I am from Pakistan 58years old I am a retired person and
doing TV repairing as hobby I have a Philips 21" TV model no 21pt2682/65r
problem is TV is totally dead there is no short S.M.P.S is not working please help
me.
Very very best regards
Hi Hameed,
Glad to meet you and happy to hear from Pakistan. With
regard to the TV you are repairing you have not given me any fact you have
already gathered in order for me to make any conclusions. I suggest you read
this article on troubleshooting smps on my site and I am sure it will help you.
Dead symptoms on TVs are the easiest to solve and they are
mostly power problems
Hi Humphrey
Thank you very for the reply I know that your time is very
important but you are replying too much emails from the world. I have another
TV Philips model no: PT2682/65R when I power on TV flub flubs but no raster and
no sound.
This could point to a short on the secondary side of the
power supply. Especially the fly back or surrounding components.
The other TV Nobel 29E25D chines TV screen cuts from
horizontal side like 1 inch from both sides
1. If the screen is less in width this means a problem on
the horizontal circuits. Especially the snubber capacitor has lost some value
so I suggest you replace the snubber capacitor directly and see if this problem
will go.
2. If the screen is less height this means a problem with
the vertical circuit.
I hope you will not irritate and give me detailed answer
that what should I do.
My friend Hameed, if you look at the way I have been
supporting my customers you will realize that they are the ones who supply the most important
facts because they are on the ground and then I analyze them and make some
conclusion based on the facts provided.. The more info they provide the higher
the chances of the repair will be successful.
Again my aim is not to give them the fish but to show them
how to fish…so that even if they get a challenging repair in future they can
always handle it.
Hi Humphrey,
As you told me that some short in secondary side I checked
again and found a capacitor 680pf parallel to the 95 volt supply diode in
secondary side was shorted after replacing the capacitor TV come alive but
after one hour TV come in standby mode I checked all the dc voltages all is
perfect after 15 minute later I switched it again TV starts normal but after
fifteen minutes go to standby can you help. And what is the snubber capicitor
can you explain.
First let me take up your last question (And what is the
snubber capacitor can you explain.)
This capacitor is usually rated between 1200Volts-2000volts,
it has one leg on H.O.T collector and the other leg on the ground.
As the name implies snubber capacitor is used to suppress
(snub) induced high voltages by the collapsing magnetic field in the flyback
transformer primary winding which could otherwise lead to destruction of the
Horizontal output transistor (HOT).
That is why sometimes this capacitor is also referred to as
"safety capacitor". If this capacitor is open or is removed from the
circuit it will cause instant destruction of H.O.T transistor.
If the TV is going in standby after 15 minutes it means
there is something which is getting overheated. let it run for the fifteen minutes
and switch it off and remove the power cable from the power outlet and touch
components around the flyback and see which is becoming too hot...whatever
component is getting very hot is most probably the faulty one. Be sure also to
touch the top of those big capacitors on the secondary side and see if any if
getting hot. If any is getting hot just replace it directly.
Regards Humphrey
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