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

[tw2005]

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

With your fault finding I'm curious about something.

I'm assuming you changed the LED board first, no result, so when you got the new PSU was that tested with your original LED board or with the replacement first?

[tom66]

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

A gate-source short would not occur if the LED driver were damaged though, it usually occurs due to ESD damage or excessive gate-source voltage.

[tw2005]

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

I thought it was shorted all round, anyway I'm just suspicious of 2 PSU being faulty and maybe since that transistor supplies the 24V may have been killed by the driver board.

I do wonder if that transistor is showing the same on his original PSU.

A lot of Payless parts are from damaged in transit TV, the quantities of some of the boards he has is too high for them to be from previously used TV. probably not all tested .

I asked them once because they never mention they're from new TV always listed as used.

"......the majority of our parts are indeed removed from brand new TVs that were damaged in transit, but eBay doesn't have a "like-new" category and since the parts are tested we really can't say they are new. We do hang on to a few bad boards,..."

[sfernandes]

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

With your fault finding I'm curious about something.

I'm assuming you changed the LED board first, no result, so when you got the new PSU was that tested with your original LED board or with the replacement first?

I thought it was shorted all round, anyway I'm just suspicious of 2 PSU being faulty and maybe since that transistor supplies the 24V may have been killed by the driver board.

I do wonder if that transistor is showing the same on his original PSU.

A lot of Payless parts are from damaged in transit TV, the quantities of some of the boards he has is too high for them to be from previously used TV. probably not all tested .

I asked them once because they never mention they're from new TV always listed as used.

"......the majority of our parts are indeed removed from brand new TVs that were damaged in transit, but eBay doesn't have a "like-new" category and since the parts are tested we really can't say they are new. We do hang on to a few bad boards,..."

I tested the new PSU with my original LED Driver.

That transistor tests fine on my original PSU, my original PSU has the same issue no 24v, but the issue is from some other component on it and not from that transistor.

Do you think its possible that the LED driver is killing the PSU?

[tom66]

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

What you can try doing is soldering a wire from pins 1 thru 3 to pins 8 thru 5. This will bypass the FET and make the 24V present in standby, increasing the TV's power consumption. Check if everything works, if it does, you can try to replace the FET or capacitor.

[sfernandes]

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

What you can try doing is soldering a wire from pins 1 thru 3 to pins 8 thru 5. This will bypass the FET and make the 24V present in standby, increasing the TV's power consumption. Check if everything works, if it does, you can try to replace the FET or capacitor.

I cant do that Tom because if they want the board back its going to be all hacked up.

I also removed that cap as you suggested and it still tests the same. Still faulty.

Do you think its possible that the LED driver is killing the PSU?

[tom66]

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

No, a shorted LED driver would not cause the FET to have a gate-source failure. That most likely occurred due to handling/ESD or physical shock (to the capacitor near the FET.)

[sfernandes]

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

No, a shorted LED driver would not cause the FET to have a gate-source failure. That most likely occurred due to handling/ESD or physical shock (to the capacitor near the FET.)

I removed that cap and the FET is still shorted.

[tom66]

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

Possibly ESD damage then or poor design by Panasonic overvolting the gate, I doubt the second and suspect the first.

[sfernandes]

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

Possibly ESD damage then or poor design by Panasonic overvolting the gate, I doubt the second and suspect the first.

Ok, do you know what may be faulty with my original board that causes no
24v as well? that particular FET is good on my original board. What else can it be?

I can hack up my original board, but not Payless's board cause they may want it back.

[tom66]

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

How about a little diagnosis? Repeat the tests as before on your old power board (corrected for new knowledge):

Do you have 5VS? 5V standby. Pin 5 of P2, power board.

Do you have 16V? Check before & after SUB-ON goes high. Pin 1 of P2, power board.

Can you access the leads of capacitor C7422 on power board? Check voltage ACROSS that. Expect 24V/24V before AND after SUB-ON high.

Can you access the leads of capacitor C7514 on power board? Check voltage ACROSS that. Expect ~6V standby/12V after SUB-ON high.

[sfernandes]

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

How about a little diagnosis? Repeat the tests as before on your old power board (corrected for new knowledge):

I'm going to try that in a few min.

[sfernandes]

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

Ha, tested and working. Big lie, they don't test them. But anyway, ignoring that... Let's check a few more things.

Do you have 5VS? 5V standby. Pin 5 of P2, power board.

Do you have 16V? Check before & after SUB-ON goes high. Pin 1 of P2, power board.

Can you access the leads of capacitor C7422 on power board? Check voltage ACROSS that. Expect ~12V standby/24V after SUB-ON high.

Can you access the leads of capacitor C7514 on power board? Check voltage ACROSS that. Expect ~6V standby/12V after SUB-ON high.

This power board appears to drop the supply voltages in standby to save power. Everything runs at about half nominal rating in standby.

How about a little diagnosis? Repeat the tests as before on your old power board (corrected for new knowledge):

Ok it looks as it tests the same as the payless board I got.

yes I do have 5V in standby

Yes I do have 16v when sub-on is high and 0.005v when its low

Yes I get 12 volt in standby and 24v after sub-on is high

Yes I get 6v standby and 12v after sub-on high

[tom66]

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

That power board is working fine.
Check the BL-ON signal, pin 11 of P2, and BL-ERR pin 10 of BL-SOS.

[sfernandes]

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

That power board is working fine.
Check the BL-ON signal, pin 11 of P2, and BL-ERR pin 10 of BL-SOS.

Really its working fine and i'm not getting 24v from it?

Where is the BL-ERR pin 10 of BL-SOS? on what board and connector is that on?

[tom66]

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

uh... my error, not thinking straight. Pin 10 of P2 is BL-ERR/BL-SOS.
You're not getting 24V at all on pins 7,8,9 of P4?

[sfernandes]

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

That power board is working fine.
Check the BL-ON signal, pin 11 of P2, and BL-ERR pin 10 of BL-SOS.

uh... my error, not thinking straight. Pin 10 of P2 is BL-ERR/BL-SOS.
You're not getting 24V at all on pins 7,8,9 of P4?

On Check the BL-ON signal, pin 11 of P2 I get a 3.286v and drops to 0 then comes back up and drops again it does this a few times then just drops to 0

Pin 10 of P2 is BL-ERR/BL-SOS I get 3.271V but then drops and comes back up then its just bouncing all over the place never going over 3.271V.

Nope I'm not getting 24v on pins 7,8,9 on the p4 connector the highest I get is 0.025V and just jumps up and down never going over 0.025V.

[tom66]

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

Oh, OK. Yes, your power board is still defective.
Now it will need to be removed to do some tests in particular the fuse on the 24V output PA7401 may be blown.

[sfernandes]

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

Oh, OK. Yes, your power board is still defective.
Now it will need to be removed to do some tests in particular the fuse on the 24V output PA7401 may be blown.

Ok how do I test it? do I put the meter in continuity ohms? if so then the screen just stays at OL and no beeping at all. did I test it correct?

[tom66]

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

You tested it correctly, and it is blown.

Although your new board probably wasn't damaged by the LED driver failing (if it has), your old board might have been. Can you get a picture of the LED driver? There is no schematic for it, so we'll have to work off pictures alone.