Panasonic Viera TC-L32U22 no picture

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

thanks. Just a FYI, I won't post back for a couple days, I have to go out this afternoon and have an all day thing tomorrow. Once I get the time I'll check and post back.

I appreciate it.
Jim

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

Ok, back to looking at this again...

I will look to probe the voltages but the following has directed me back to looking for a tcon fuse again.

I found the tcon board number MDK 336V-0 W (see image). I searched this forum with this number and found this:
https://www.badcaps.net/forum/showth...hlight=mdk+336

which lead me to this:
https://www.badcaps.net/forum/showthread.php?t=32742

The last thread is for a panny 32" but not the same model number as mine, but the tcon board number is only different by the last character (a small difference like shape?). I am thinking that perhaps the board might be very similar in design, so perhaps there has to be a fuse, as initially suggested in this thread.

Have I jogged any memories? I am assuming that the logical place on the fuse would be on the tcon board as opposed to the A board. Thoughts?

Jim

[budm]

Re: Panasonic Viera TC-L32U22 no picture

But your LCD panel uses integrated T-CON, not separated T-CON like in the other threads.
If you do have 12V on one of those pin of the LVDS connector pin then at least we know that the main board does send at least the switched 12V (main board sends other Voltages as well as you can from the schematic you provided) to run the T-CON board, that is why we need to test the for 12V at least on that LVDS connector.

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

ok, here's where I am at.

I could not get any significant voltage readings at the panel ribbon connector, specifically I could not find AVDD at pins 72-76, it was easy to probe.

I then went back to where the power supply board (P Board) supplies the A Board. See the attachment. I found 12V at the connector, but when I went to IC4800, I couldn't find it present at the IC and connected C's and R's. Note that there is a fuse, PA4800 which may be the culprit, but I can't fine it at this moment. Note that there is also a PA4801 and 02 fuse on the AVDD 13.7 and 2.5 lines respectively, but not sure if they are in play until I find the 12 at IC4800.

Does anyone have a picture of what these fuses might look like, or how they differ from the other SMY components (in appearance)?

Jim

[budm]

Re: Panasonic Viera TC-L32U22 no picture

It will be small SMD fuse which can be on the top side or the bottom side of the board, you can also trace out the connection of IC4800 that should go to the fuse.

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

I have looked on both sides. How do they differ in appearance? color? indicator? there are no component numbers on the board

[budm]

Re: Panasonic Viera TC-L32U22 no picture

So you cannot trace out the connections from the IC to the fuse?
Show good clear high res straight shot of the whole top and bottom side of the board, I also need the P/N of the main board (P/N of the blank PCB and P/N as printed on any stickers on the main board.
Also upload the service manual have.
Does the service manual show the PCB layout with part designators?
Sometime the manufacturers will print all the part desigantors on the board which makes it hard to troubleshoot without the service manual.

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

Hi, thanks for sticking with me. I appreciate it. I don't really have a use for this TV now, but I get a kick out of fixing things. Having said that, if I do give up at some point, no biggie. I have alot of other things on the "project bench" waiting.

First, lets agree that we are both talking about the A Board, not the integrated Tcon board on the panel. I am not seeing voltage leave the A board.

I'll take some full board shots in a little bit, both sides, and also the area around IC4800 closeup.

I'll take a closer look a little later at trying to follow the traces, but as you know with multiple layer boards (2 layer, 4 layer?) it can be a challenge.

The service manual can be downloaded from a link at the beginning of this thread, page 1.

The service manual does show the PCB layout and component designations in some cases, but it's not really readable (cant magnify clearly) , and doesn't seem to have more info than is printed on the board.

See page 54 of the service manual, IC4800 is in quadrant B2. It seems like that is as close as they point you.

The fuses PA4800 - 4803 are only listed on page 72 in the bom.

Like I said, I'll take another look a bit later today.
Jim

[nomoresonys]

Re: Panasonic Viera TC-L32U22 no picture

Is this your mainboard? https://www.shopjimmy.com/panasonic-...tc-l32u22.htm#

[budwich]

Re: Panasonic Viera TC-L32U22 no picture

the easiest way to attempt to trace a board without knowledge / "paper work" of the circuit is use your meter on the resistance scale with or without the "buzz" for "continuity".
In this case start with the probe at the 12v of the incoming connector. Use the other probe and work your way to a "continuity point" on the other side of the connector and in the direction of the "known ic" as you have the "block diagram flow" which can readily guide you. You will likely come across the component in question regardless of whether the board is multi-layered or not (it is more than likely only two).

[nomoresonys]

Re: Panasonic Viera TC-L32U22 no picture

Mainboard there if its a match, 57 bucks seems high but theres a make offer option. https://www.ebay.com/p/Tnph0857ae-Pa...u22/1524512642

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

ok, haven't spent any time on it today. I'll start tracing via continuity tests. I'm not thinking any more pictures are going to help because I don't have a good closeup lens, and aren't the res/size of jpegs limited on this forum?

Replacing the board isn't really much of an option at any kind of $ because you can get 32" sets new for a little over a hundred, and I would be buying a board not knowing for sure it's the problem, and even if it was, why did the board fail in the first place?

Compounding it's fate is that I don't have an immediate use for it. I just hung on to it as a "maybe I can fix it".

The one thing that would really help a description of how these fuses differ in appearance from the other 2 pin SMT C's R's D's, and what package size might they be?I see a couple funky looking things on the board that I perhaps could take a photo of through a magnifier.

Jim

[nomoresonys]

Re: Panasonic Viera TC-L32U22 no picture

No doubt, I wouldnt pay more than 20 bucks for a 32 board and thats only if a 32 was ideal for a situation where a bigger tv couldnt be used.

[nomoresonys]

Re: Panasonic Viera TC-L32U22 no picture

Post #49 has pretty good pics. in case it helps someone trying to trace, would never pay 86 bucks, lol.

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

ok, here is the latest. I think I have been chasing down the wrong path, but it has been a fun chase.

From the beginning I was looking for a fuse link to supply 12 to the panel. I found that voltage was present on the main board, but not the panel.

However, I think I was off in chasing down a fuse in the supply path. I put together a combo image of the block diagram (on the left) and schematic (on the right) sections of the area I have been focusing on. See the attachment.

I have found that the 12v comes onto the processor board via an edge connector from the PS board. Good. I traced it right to the IC (4800) that supplies the 13.7v and 2.5v to the panel. Good. So, the suspect 4800 fuse is ok. All good.

What I have found is there is no voltage (13.7 and 2.5) coming out of IC4800 (a panasonic asic?). Not good. The block diagram represents two enable pins as "switching" the generation of the 13.7 and 2.5v. I suspect these enable lines. I measured them and found about 2.5v on them with the power on. Doesn't seem like a logic level to me.

so, I think that this has progressed past a "look for a fuse" exercise. Might be time to button it up and recycle unless anyone has a "if it's an enable, check this" thought

Jim

[budm]

Re: Panasonic Viera TC-L32U22 no picture

What is the IC4800 P/N so we can look up spec sheet to see what the required Enable Voltage level should be.
Do those two control signal change state when TV is toggle OFF/ON? They should change state.

[budwich]

Re: Panasonic Viera TC-L32U22 no picture

are you watching the voltages at power up / standby / power ON. They may only be there for a short time (1-2 sec) if there is a problem shutting down the switching/regulation.

Further, it would appear that 2.5v is a "good voltage" as it is sending that same voltage level to the tcon to help with its work.

As suggested by budm, watch the two "enables" during the states mentioned as see what happens to them. Then do the same with the two outputs.

Further, check the "state" of the "panel power sos" line.... that will likely tell you whether the chip is "happy".

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

There is no part number on the IC itself.

The IC part number as listed in the service manual is C0DBZYY00343. A search of this returns nonspecific "panasonic part". That's why I said "Asic?". You can see this part number on the schematic portion of image I supplied as well.

Another part number listed on the schematic image is BD8191MUV-HVE3, which returns that is is made by Rohm (and others) but I could not find anything more specific.

I have done all measurements at power on (press power - click and observe backlight on). I have not mentioned before that the outputs are about 0.5v.

I can measure the states of the enables and the outputs through the states you mention, but what do you define as standby? Plugged in, but before pressing power?

Jim

[Redrum]

Re: Panasonic Viera TC-L32U22 no picture

I'll included the sos when I remeasure later today....

[budwich]

Re: Panasonic Viera TC-L32U22 no picture

things happens at power up (plug in), again at "steady state standby" (ie. once powering has been on for a bit) and then again at "power ON" (ie. pressing power on). You are looking for "state changes" to see if some portion of a "cycle" isn't happy or completing... that may help determine where the source of the problem is.