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Horizontal Output Transistor

I suspect my HOT on my Philips 7P5441C is shorted. How would I go about testing the HOT? And, if it is bad, where can I find a replacement? I've done a few searches, but haven't found any results.

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Re: Horizontal Output Transistor

This philips board give many problems with no raster. Most times its Horizontal and sometimes it transformers I have found it would be much simple to buy board or send off to be repaired. Pts 1800-844-7871 is the best bet. You also can get hot at places like MCMelectronics, bluestar international, tritronics. If you do not want to buy board.

Posted on Sep 19, 2007

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Pt 56wx 33g panasonic tv blinks 5 times ,i tested with out the covergence chip and still blinks 5 times

Three blinks is the indication of the convergence IC's. The five blinks that you are seeing is from another source. You have a short in your High Voltage Circuit, I would suspect the Horizontal Output Transistor or HOT. It should be IC401 on this set. If you test it in circuit the transistor is coupled with a tranformer and a diode. The best way to test it is to pull it out and use a diode tester on it, you should not read 0 ohms on any lead, if you do it is bad. You may also have a bad flyback transformer that may have caused the problem, also check the coil that feeds the trasistor for ring cracks and repair them at the same time.

This should help you get this set up and running.
If you have any futher questions please respond to this post.

Thanks for using FixYa

Feb 03, 2011 | Panasonic PT-53WX52 53" Rear Projection...

2 Answers

No power

Ypu will first have to check the horizontal output transistor and make sure it is not shorted. The voltage for the horizontal output transistor comes from pin14 of the SMPS transformer. Then it goes through the coil,L815, then to the diode for B+,D825. Then the B+ goes through coil L816. Be sure after D825 you check the capacitor, C830, as this is a very common fault with this set. Then the B+ flows through L817, then through two One ohm resistors, R857 and R858 to pin8 on the flyback transformer. If you get B+ on pin 8 of the Fly, and none on the horizontal output transistor, the fly is open and is bad. I have a schematic that is very close to this set but not an exact one, but most of these sets are about the same, and if you know anything about Panasonic TV sets, you should be able to repair them with a schematic from another set. BTW, this Horizontal and fly circuit is on the D board. If you wish to have a copy of the service manual for a set close to yours, I will send you a copy. If you follow these instructions, you should be able to find the fault with this TV set. If the SMPS is not working, you will not get any voltage also on the HOT. Good Luck

Jul 02, 2007 | Panasonic PT-47WX49 47" Rear Projection...

1 Answer


sometimes when shorts or sparks occur in the viciity of the flyback. compnents take a hit. if i had this set in my shop i would first check what is called the horizontal output transistor. this transistor is directly related to flyback and i would suspect it to be shorted. certain capacitors and diodes also can short under the same situation. And theres a possiblility that the flyback is bad

Oct 14, 2010 | RCA HD52W59 HDTV Projection Television

1 Answer

The tv is a Magnavox 51MP392H/17 and has sound but no picture. Any ideas?

TV is in high voltage shutdown protection mode. Check to see if Horizontal output transistor is shorted or open. If not then resolder all solder joints on HV transformer. If this does not fix it then you will need to do voltage checks off of H.O.T. and then possibly a bad HV transformer.

Apr 30, 2010 | Philips Magnavox 51MP392H Rear Projection...

1 Answer

I had a 15 second power outage; my Philips 60PP9202 doesn't come on anymore (there is just a very faint "chirping" noise that is audible. Is there a reset button somewhere?

This is usually the flyback transformer (IHVT-integrated high voltage transformer) and the HOT( horizontal output transistor) The transistor will read shorted, with a multimeter, if it is bad. It is mounted to a heatsink straight back from the flyback. It may have a metal clip that holds it tight to the heatsink.
It is a pretty easy fix if you can solder.
While you have the board out, check for any discolored resistors or blown capacitors and replace those as they will likely fail before long and cause more problems. Also check with a bright light and a magnifier for cracked solder joints and resolder any that you find.

Feb 12, 2010 | Philips 60PP9202 60" Rear Projection...

1 Answer

Philips 60pp9202 I get no sound, no picture and a chirping noise

Chirping in a phillips is usually related to the HOT ( Horizontal Output Transistor) or the Flyback ( HV Generator having a issue.

Dec 11, 2009 | Philips 60PP9202 60" Rear Projection...

1 Answer

Philips 55PP9352 Rear Projection, no picture or sound. When the power button is pressed the red indicator light comes on and there is a chirping sound coming from the back. The convergence chips...

FBT is on power suplly deflection board it has 2 wires coming from it one goes to high voltage trippler box the other 1 goes to screen control box Hori out put is next to FBT 3 legg transistor on aluim heat sink Base to emitter will read short has internal Diode if it reads short on base to collector then hori output is Bad. Call Mats for Parts they will send you a catolog if you ask them too! 1-800-628-1118 Let me know if you need any more help.

Sep 10, 2009 | Philips 55PW9363 55" Rear Projection...

2 Answers

Rca p52927 chassis ptk 195 wont power up all of a sudden

ctc chassis with the 195 chassis were famous for flyback transformer shorting and taking out the horizontal output transistor also.

Oct 24, 2007 | RCA P52937 52" Rear Projection Television

2 Answers

Hitachi 53UDX10B

With the set unplugged check the horizontal output transistor, horizontal driver transistor and the horizontal driver transformer, for shorts, cold solder joints. Next if all checks ok, suspect the convergence IC's and related circuitry.

Jul 04, 2007 | Hitachi 53UDX10B 53" Rear Projection...

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