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Philips Plasma 42PF9965 fault - won't switch on
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Pacovich
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PostPosted: Fri Dec 29, 2006 9:23 pm    Post subject: 32PF9965 Reply with quote

Don't you love the term flyback, minnie? No problems with the name we give it. I refer to the transformer of the first switching power supply of the system who is sometimes called also flyback, position 5500.
It is on all the time the plug is connected. Also while the main switch is off. Its quality aspect is not very good in my opinion but in the photographie in an official document its aspect is very good. I think they made any bad ones in the beginning and after some defaillances they changed the design or the level of quality (I say I think).
I have tested severals capacitors next to the supply and they seem to be ok. I change the voltage reference IC TL431 and it's not the problem. The optocoupler seems to be ok. The TNY256 is capable to autolimit itself and I think it is doing due to any primary coils in short-circuits that overload it.
I think in a problem in the primary of the transformer. The external coils are not isolated and I don't expect a better situation internally.
I envisage a solution that I don't love very much: installing extra supplies in order to provide 24V, 9V and 3V3 external to the mainboard, adjust the voltages to simulates the original situation. It's also necessary to nullify the original supply. If anyone does it, it will be absolutely at his own risk.
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minnie



Joined: 18 Aug 2005
Posts: 2880
Location: Hell

PostPosted: Sat Dec 30, 2006 4:53 am    Post subject: Re: 32PF9965 Reply with quote

Pacovich wrote:
Don't you love the term flyback, minnie? No problems with the name we give it. I refer to the transformer of the first switching power supply of the system who is sometimes called also flyback, position 5500.
It is on all the time the plug is connected. Also while the main switch is off. Its quality aspect is not very good in my opinion but in the photographie in an official document its aspect is very good. I think they made any bad ones in the beginning and after some defaillances they changed the design or the level of quality (I say I think).
I have tested severals capacitors next to the supply and they seem to be ok. I change the voltage reference IC TL431 and it's not the problem. The optocoupler seems to be ok. The TNY256 is capable to autolimit itself and I think it is doing due to any primary coils in short-circuits that overload it.
I think in a problem in the primary of the transformer. The external coils are not isolated and I don't expect a better situation internally.
I envisage a solution that I don't love very much: installing extra supplies in order to provide 24V, 9V and 3V3 external to the mainboard, adjust the voltages to simulates the original situation. It's also necessary to nullify the original supply. If anyone does it, it will be absolutely at his own risk.


A flyback transformer (FBT) or line output transformer (LOPT) is a type of transformer used in the power supply that generates the high voltage needed for driving a cathode ray tube (CRT) or "picture tube". It generates a voltage of a few kilovolts for a monochrome tube, or 10 to 30 kilovolts for a color tube. Unlike a mains (line) transformer, which works with sinusoidal alternating currents at 50 or 60 hertz, a flyback transformer operates with switched currents at much higher frequencies.

Plasma's don't have crts. I love flybacks btw.
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Pacovich
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PostPosted: Sat Dec 30, 2006 1:01 pm    Post subject: The transformer of the first switching supply in a xxPF9965 Reply with quote

It doesn't matter, minnie.
In my monitor, the problem is focused in the transformer in position 5500. It has a primary at 410V and three secondary at 3V3, 8V7 and perhaps 25V. I think the problem is generalized to all the set with that transformer type.
The object of this post is, I think, to help to find a solution and I intend it.
It's very difficult to me to express this in english because I am spanish but I think the principle of both type of transformer is the same. Thus, someboby could call it 'flyback' but now this is not our problem.
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Pacovich
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PostPosted: Sat Dec 30, 2006 3:10 pm    Post subject: Transformer CE165T Reply with quote

BTW, where can I get a CE165T transformer. I think we haven't a free market in Spain (Europe) and its purchase is restricted.
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Pacovich
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PostPosted: Mon Jan 01, 2007 10:57 pm    Post subject: Switchmode power supply in a 32PF9965 Reply with quote

After the last tests I think the problem is in the SB340 diode. It is an scottky diode, a rectifier working at high frequency, and it is kaput. The test with the ohmmeter result ok but that is not the same situation when the set is on.
In the theory, the SB340 must allow the current in only one direction but, in fact, it allows both senses and that is equivalent to a short circuit in the transformer. Now, I understand this deficiency may be degenerative because of the continuos stress.
I had the control part of a low consumption lamp that contains 2 diodes 1N4007 that is also an scottky type and is capable to work at high frequencies but only at 1 Ampere, enough to test the supply without consumers at all its output.
The SB340 has a foward voltage of 0.5 V but the 1N4007 has a ramp around from 0.6 to 1.1 Volts. When I have put on the supply, the regulator has had to rise 0.4 V (the excess from 0.5 to 0.9) the output that is normally at 3.3 V because of the superior foward voltage, thus the output that have normally 8.7 V had been rose in a similar proportion at (3.3+0.4)/3.3*8.7=9.75 V. This is a simple theory but also the reality in my tv monitor set. Thus, I have purchase 5 diodes SB340 an hour ago. It is too late for Santa but in Spain we still await the Magi.
Finally, it is not neccesary to purchase the dum flyback transformer. I expect this information will be useful to others.
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Pacovich
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PostPosted: Thu Jan 04, 2007 6:16 pm    Post subject: My flat monitor has died Reply with quote

I have verified the all supply card complex and it is not a problem in the supply system. The protection is active. Two weeks ago I have read the lines Errors1 and Errors2 and there was an error code relative to the PDP (the screen). I throw in the towel.

My flat tv is died, long live the flat tv! I'm going to purchase a new other. But never again Philips.

Sorry, Tim_UK, the record is mine: 5436 hours for a 32PF9965 with plasma ALis.
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Tim_UK



Joined: 19 Dec 2006
Posts: 7

PostPosted: Thu Jan 11, 2007 9:48 am    Post subject: Reply with quote

latest on my set is - will never switch on (just the flashing warning mode led) if room temp under 19 C - by heating room above this (esp with heater under telly) will come on, touch wood.

also notice some of the rubber (?) sealant between the glass and the case at the top of the screen has come adrift - maybe something in the past has overheated inside ??
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runningman



Joined: 26 Dec 2006
Posts: 7

PostPosted: Thu Jan 11, 2007 10:33 am    Post subject: Reply with quote

Hi

Still no joy here, no mater what temperature...

LED light still just flashing red
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NAZ
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PostPosted: Mon Mar 12, 2007 7:18 am    Post subject: PHILIPS PLASMA 42PF9965 FAULTY : Flashing Red LED Reply with quote

I have a 3 year old Philips Plasma 42PF9965 with external tuner box FTR9965 and just like runningman & Tim_UK's plasma, it will not switch on.
This problem started about 4 weeks ago and after switching it on and off several times the plasma did come on, but now it refuses to switch on with a flashing red LED.
Anyone know if the problem is with the Plasma Panel or the external tuner box?
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runningman



Joined: 26 Dec 2006
Posts: 7

PostPosted: Mon Mar 12, 2007 7:43 am    Post subject: Reply with quote

pretty sure its the panel - although still not got mine to work.

the must stupid thing about it is only one company in the uk will look at them and they charge £1000 to just look at it - daft when you can now buy these new for less than that.
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