Panasonic TC-L47E5 won't turn on [3 red blink code]

[corksil]

Hey guys, first post.

A 47" LCD popped up in the free section of craigslist and I nabbed it for 20 bucks. I'm super busy with work so I haven't had a chance to get into the repair project yet (it's been sitting in my garage for a few months..)

Today I found a few spare moments and found an owners manual [for TC-L47E5] and service manual [for TC-L47E5T] in PDF format.

Plugging in the TV results in a steady repeating 3-blink red light on the bottom front center of TV. (Blink, blink, blink, pause etc) The service manual says "IROM Boot Program SOS" and check "A-board" and "P-board.

I'm hoping to take this thing apart soon and wondering what to look for. I fixed an electric cook top recently by replacing a few swollen capacitors on an internal PCB so I should have the skills to get this TV working.

Any info would be appreciated. I will treat this thread as a working log for the repair process in hopes that anyone with a similar issue can benefit from the info.

If I can repair this TV and make it usable it will be a massive upgrade to my current TV.

Thank you all for any contribution or info shared!

[dick_barton]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Do you have any sharp photo's of your circuit boards and interconnection of the boards.
Do you have your 5V, 16V & 24V supplies on the power board

[dskall]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Well have to wonder why you pay $20 for free tv but ok lol

[Andrew F. Ali]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Could you upload the Service Manual for us to look at please?

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Okay guys. After making this post I had a wicked motorcycle accident and have been out of commission since then. Now I'm getting back to my old tricks, and still want to fix this TV.

I'm going to take it apart now and look for any signs of electrical failure.

I uploaded the service and owners manuals at the bottom of this post.

Thank you all for helping, I'll check back after I take this thing apart. Hopefully this is all worth the effort and won't end up being a waste of time. The service manual is 78 pages long so hopefully it has some useful info.

I'm off to check the "a-board" and "p-board" as directed by the three blink code.. "IROM Boot Program SOS".

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Alright. I'm figuring this out as I go.

Do you have your 5V, 16V & 24V supplies on the power board

In the service manual, 3 blink code says check p-board and a-board.

Page 33 has a 'voltage chart of the p-board' with the following values listed below.

I found a schematic for the p-board (presumably power) on page 55, with locations for the six TPxxxx listed in the diagram on page 33. I'm assuming that "TP" means "test point."

for 5V there is TP7412 and TP7507 -- I have 5.31v at each TP (correct)

for 16V there is TP7508 and TP7513 -- I have 0.1mv at each (INCORRECT! supposed to be 16v +/- 0.6v)

for 24V there is TP7512 and TP7513 -- I have 0.0mv at each (INCORRECT! supposed to be 24v +/- 1.2v)

So... what does this mean? I don't see any swollen capacitors on any of the boards, and this TV does absolutely nothing except the power button "blink blink blink, pause.. blink blink blink, pause.. etc"

Please help!

[dskall]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

You checked these voltages when you tried powering set on? Not just in standby. The fault code looks more like a corrupt firmware.

[dick_barton]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

What PFC voltage do you have at TP7201/TP7203 (pdf a little blurred)

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

You checked these voltages when you tried powering set on? Not just in standby. The fault code looks more like a corrupt firmware.

Now that I think about it.. the TV probably was in standby. Connecting the power cord caused a tiny red light on the front/center/bottom of the TV to blink three times, pause, and repeat. None of the buttons on TV or remote seemed to do anything. That little light was steadily blinking as I removed the back cover from the TV and tested all of this stuff.

What PFC voltage do you have at TP7201/TP7203 (pdf a little blurred)

I will check that in the next hour. Really want to get this thing fixed.

Thanks for the help guys!

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

TP7201 is rock solid around 64vDC

TP7203 fluctuates around 1vDC, Tested again at -16vDC, then tested a third time and is fluctuating around 100-200mVDC. Seems likes the reading is all over the place..

Anyone?

[dick_barton]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Those voltages don't sound correct. Can you measure by placing your probes across the two terminals of CT215, the capacitor connected to test point TP203. It should be close to 400V DC.

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

I was testing from the TPxxxx flat round solder spot to ground (chassis of TV). Perhaps that was incorrect.

Gonna go re-test as directed now.

For what it's worth, the TV doesn't seem like it's "on" -- and none of the buttons on TV or remote have any affect. When plugged in, the only thing that happens is the repeating 3-blink code on the red LED on front of TV.

Back in a minute!

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Okay first picture is component side of the p-board (capacitor CT215 is the big one in upper-middle)

Second picture is green side of p-board

Third picture is closeup of capacitor area from green side showing TP7201 and TP7203 area.

Testing between the terminals of capacitor from the component side shows me 166vDC. Same 166vDC when testing with one multimeter probe on TP7201 and the other on TP7203.

[dskall]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

For clarification on power board you have a side marked hot and a side marked cold with lines around each. All measurements on hot side. The ground reference point will be neg. of your main filter cap. For cold and all others the ground will be chassis.

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

The ground reference point will be neg. of your main filter cap.

Thanks for clarifying, I've never done this sort of repair before. Could you further explain "be negative of your main filter cap.." -- I'm assuming you mean capacitor, but which one is the main filter capacitor?

[dskall]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Yours is the black long cap on hot side

[dick_barton]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Have you got 16V at TP7414/7415 and 12V at TP7430/7431. Use chassis as ground.

[dick_barton]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

You have the PFC voltage given earlier and also the standby voltage. The 16V and 24V should be available at the output connector when Pin 7 of P2 goes high switching on Q7401.

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

Have you got 16V at TP7414/7415 and 12V at TP7430/7431. Use chassis as ground.

I'm reading 11.5v between TP7414 and chassis/ground.

Also reading 11.5v between TP7415 and chassis/ground.

I'm reading 7.5v between TP7430 and chassis/ground.

Also reading 7.5v between TP7431 and chassis/ground.

Here's a picture of my test... Red probe goes to test point on p-board, black is to chassis. I have aligator clips [presumably] grounding the p-board to the chassis so it "thinks" that it's all assembled correctly. There's no way to reach the test points with the board bolted to the chassis. The book under the p-board is insulating anything from the component side from shorting to the chassis as well as propping the board up at an angle. Pretty sure I'm doing this right.

[corksil]

Re: Panasonic TC-L47E5 won't turn on [3 red blink code]

You have the PFC voltage given earlier and also the standby voltage. The 16V and 24V should be available at the output connector when Pin 7 of P2 goes high switching on Q7401.

Please have mercy but that doesn't make as much sense to me as it should.

I looked up "PFC" and it means power factor correction - which doesn't make much sense but it doesn't have to if I can fix this TV without learning about it.

16v and 24v should be available at the output connector when pin 7 of p2 goes high switching on q4701.

Okay I'm deciphering your words. 16/24v at the p2.. I see the p-board has two ribbon cables attaching it to other boards. One is marked p4, the other is p2 so that must be the one you're referring to. Pin seven.. I see a marking on either side of the p2 connector --- 1 and 15 on the other end so it must be a 15 pin connector, and pin seven is now located.

Which one is the output connector and what is q4701? I don't really need to understand how all of this works (honestly I find it fascinating and I'll teach it to myself at a later point in time but don't need to know it now.)

Thank you all for helping, you guys are freakin genius if you understand how all this works.

Is there a possibility that this connector has become corroded or rusty and could be causing this problem? Just a thought..