Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

I mean one probe on 1 and one probe on 4.

Ok pin 1-4 is 0.048 and a long beep

pin 4-5 same thing

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

I don't know if I'm doing this right tom, does my meter have to be in continuity vdc? or on continuity ohms?

My meter is a Fluke 177 True RMS. I have a yellow button on the right that changes the continuity setting from ohms to VDC.

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Continuity ohms, there is no such thing as continuity VDC.
You have a shorted FET. That is good. Well bad because your power board is bad. But good for you because it can be replaced. What is printed on the device?

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

I cant really make out what is printed on the device. I'm just going to request a replacement board. Why should I have to fix a board I paid for. For that I would fix the original one that was in there. When measuring that component what should the reading be if its not faulty? from pins 1-4 and 4-5?

[tw2005]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

I think what he means is continuity mode (displays ohms), diode mode ( displays volts) from what i can work out ,looks like you can toggle this option .

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

I think what he means is continuity mode (displays ohms), diode mode ( displays volts) from what i can work out ,looks like you can toggle this option .

Yes that's what I mean. What option should I have it on for testing this Mosfet?

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

First mode. Continuity.

[tw2005]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Q7403 is also the same component, out of both PSU none a legible?

Just some thoughts, options,


If this is the only part faulty,

1.check the same parts on your original PSU, maybe scavange one off that.

2. if the same part failed, get a refund , identify and purcahse just the transistor

3. get another board from payless, i've had good service from them so far.

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Just a thought could also be C7428/C7429 which is shorted, the set should work with it removed. (It is for soft-start / radio interference suppression when suddenly switching FET on.) Can remove it for quick test. Check resistance after removing it. If it's still low then the FET is dud. If not then it should work.

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Just a thought could also be C7428/C7429 which is shorted, the set should work with it removed. (It is for soft-start / radio interference suppression when suddenly switching FET on.) Can remove it for quick test. Check resistance after removing it. If it's still low then the FET is dud. If not then it should work.

I don't know about the FET its very hard to test because my probes are not super skinny. I can get it to make a steady beep sometimes then sometimes it doesn't beep just gives a reading of 45 ohms, so I really don't know what to think. If it wasn't faulty what should the ohms be?

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Open circuit, infinite, "no reading".
Maybe it will be easier to test across R7409, that is same as testing across 1 to 4.
You are definitely seeing OHMS (Ω) not KOHMS (kΩ) right?
There is a 47 kΩ resistor on the board between 1 and 4, but that's not going to have an effect on a low ohm scale.

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Open circuit, infinite, "no reading".

So what does that mean, can you please explain?

So if its not shorted it should have no reading?

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

The meter should show "OL" meaning "open loop" or "open circuit". Same reading as if the probes are not touching. That is what source to gate on a functioning undamaged MOSFET should test as.

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

The meter should show "OL" meaning "open loop" or "open circuit". Same reading as if the probes are not touching. That is what source to gate on a functioning undamaged MOSFET should test as.

Oh ok so then mine must be bad because im getting 45 ohms on pins 1-4 and 4-5 right is that correct that its bad?

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Yeah, that's bad.

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Yeah, that's bad.

Yeah I just tried testing across R7409 because it is easier and yeah its for sure shorted. Would those 2 caps you mentioned make the fet faulty? like if the caps are bad and I remove them like you say can the fet test ok?

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Yeah I just tried testing across R7409 because it is easier and yeah its for sure shorted. Would those 2 caps you mentioned make the fet faulty? like if the caps are bad and I remove them like you say can the fet test ok?

I guess what I'm asking is can those 2 caps make that fet test bad?

[tw2005]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Q7402,7403 = B1CHRE000005= Toshiba H-FET, TPC8116-H Silicon P-Channel MOS Type (Ultra-High-Speed U-MOSIII) -40V, 7.5A, 1.9W

if you still need this information.

[tom66]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

I guess what I'm asking is can those 2 caps make that fet test bad?

Only one. C7429. Can see clearly now I'm looking at PCB (thought it might end in 8.) Yes it can make it look bad. Try lifting just one end of it then check again.

[sfernandes]

Re: Panasonic TC-L47E5 LED TV blinking red power light PLEASE HELP

Only one. C7429. Can see clearly now I'm looking at PCB (thought it might end in 8.) Yes it can make it look bad.

Ok Tom thank you very much for your help I greatly appreciate it. Also thank you to tw2005.

I'm going to remove that cap in a few hours and ill report back my findings.