Sharp LC-52LE640U - DET_PNL12V failure

[newtothis]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Sounds to me like the panel is stuffed, Heat and cold can make thing expand and shrink which can effect temp shorts... Seems like left side is bad.

See what others think

[mp3car]

Re: Sharp LC-52LE640U - DET_PNL12V failure

That is kind of my suspicion as well (left side panel issue), which is why I took the left side of the metal frame off the panel (carefully, as taking apart the panel itself obviously get's risky regarding structural integrity of it)...

I am hoping that if it's a panel problem, then maybe it's a short somewhere in the ribbon wire running around the panel along the bottom and up the left side since the integrity of the glass looks fine, and it seems like a random short within a panel that isn't cracked wouldn't be a common occurence, but perhaps it is???

If it's a faulty connection to the ribbon wires, or crimped/chaffed, then perhaps I can fix the short, and get a new t-con if I need to... However, if it's the ribbon (nearly clear - because wires are so small) between the connector interface boards (that run along the edge of the panel) and the glass itself, then I can pretty much forget fixing it... But if it's between the top and bottom connector boards, or the cable running around from the bottom up around to the left corner, then perhaps it might be fixable...

It's just confusing though that the left side alone does not trip the error, nor the right side alone... in other words, adding the known "good side" of the panel to the mix with the suspected "bad side" makes it trip the 5-2 code, but the bad side alone doesn't... Perhaps it is something shorted in the panel and the error is only tripped with both connected because perhaps it's based on total current drawn by the ASIC or the t-con board as a whole (which means "monitoring" would be done by the PS board), AND perhaps the reason I don't no longer see the left half of the image with just the left cable connected is b/c there's now a problem with the drive after unning it for 30m, OR the short is bad enough to cause complete lack of image, even though it worked two days ago... That's the most frustrating part, it worked for 30m just fine... turned it off, now it's giving me all these issues... I was hoping I could just throw a heat sink on the t-con chip since keeping it cool seemed to keep it running...

FYI, with the power disconnected from the t-con board, I get the same 2-5 error that I get if both outputs to the panel are connected...

Last thought, for the moment anyhow, is wondering that if the left drive of the t-con board is shot because it overheated perhaps, then wonder if the short isn't bad enough that if I get a new t-con board and put a heat sink on the t-con's ASIC (at least I'm assuming that's what that main IC is), then perhaps it could "live" with the short, this is reason I want to swap outputs and drive the right side output of the t-con into the left side of the panel to check the left panel operation fed from a known good output channel of the t-con, but of course very short-term operation (this will test left side of panel), AND try to drive the left side output of the t-con into the right side of the panel since i know the right side of the panel is good (this will test left output of t-con)...

In addition to my question about the pinouts of the left and right side t-con outputs being the same, is it typical for the main chip on a t-con board to get too hot to touch for any length of time? In my experience, ICs can get 'warm' to the touch of course, but if it's too hot to touch, then something is wrong, OR, it was designed for a heat-sink and it's missing...

If anyone can answer whether the pinouts of the two outputs are the same of the t-con board are identical, and if it's typical for t-con chip to run hot, or has any other suggestions to try, it'd be a great help!!! I really hate to scrap a set that seems to be "almost" working, especially since I was "teased" with such a huge screen with a good picture for 30 minutes, the size was a big part of the tease considering my largest "modern" TV is a 50" Panasonic plasma (after PDP technology acquisition from Pioneer)...

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

There are ICs in the flexible PCB that can go bad. They run hot.

[mp3car]

Re: Sharp LC-52LE640U - DET_PNL12V failure

@budm

You think the Sharp has ICs like that too? Are those parts that can be easily obtained? It seems like boards are all over the place on the web, internal cables don't seem to be quite as easy to find from what I've seen on other threads...

From reading other posts of yours in other threads, you seem very knowledgeable on repair... By chance do you know the answer to my question about the outputs from the t-con board being the same pinout for each half of the screen, so that I could drive the right side of the panel with the left output of the t-con board, or the left side of the panel with the right output?

Any thought as to why it does NOT go into protect with either half by itself, but with both halves it does? Is it perhaps that it's looking at total current to the ASIC and the short isn't enough to trip it, but the short and both halves is too much? Or is it perhaps total current to the t-con board as a whole, which means the PS board would be the one to shut it down??? if the latter is true, then it makes me wonder what would happen if I forced 12V to the t-con board, but I know that's asking for trouble!

[ggil44]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Hi, didn't want to give up on the bad panel issue either (LC-70LE650U).
Maybe half of the panel failing is more common than we think.
I would like to know how difficult it is to trace the ribbon
cables for a possible fault. I guess it's worth the effort
since I have nothing to loose.

Thanks again for all the help, good advice, and information.

[budm]

Re: Sharp LC-52LE640U - DET_PNL12V failure

The ICs are not replaceable. You need to disassemble the panel to see them. The flexible PCB is part of the LCD Glass panel, the flexible PCBs are then bonded to the rigid PCBs.

[mp3car]

Re: Sharp LC-52LE640U - DET_PNL12V failure

budm is right if the ICs he's talking about are in the "film" ribbon wire that connects the glass to the rigid PCBs that run along the sides of the panel. The PCBs along the sides are considered part of the panel and are very likely an impossible part to procure individually, let alone replace one.

I am just going to be VERY hard to convince that it's a dead left side panel, UNLESS it died "the rest of the way" after taking ownership of it (free). As I said, it worked for me for 30 minutes the other night without issue, other than the main IC on the t-con board getting hot, I even moved the set around slightly while it was working, etc... No issues (again, other than the t-con ASIC getting very hot, btw - someone please correct me if that's not an ASIC so I don't perpetuate incorrect info). But then, I turned it off, came back the next day, no logo at startup, 0.5-5 seconds later the backlight goes out (although as I mentioned, now I can get a logo if I only connect the right side of the panel to the t-con board).

That reminds me, regarding the 0.5 to 5s.... If it's been off for a while, when i turn it on, the backlight will run for about 5 seconds before going dark (backlight off), and then soon after give the 2-5 code. If I've been "messing with it" for a while, when I turn it on, the backlight will only run for 0.5 seconds before going dark. I am not sure if it's the same time until I get the error code or not, or if perhaps that comes quicker as well... I will do a little more "data gathering" tonight... I don't know what kind of resources you have budm, but any way you could help me determine whether I can swap the L/R sides out of the t-con board??? I am getting close to taking my chances and giving it a shot...

[mp3car]

Re: Sharp LC-52LE640U - DET_PNL12V failure

Bad news, one of the ICs in the flex board/cable has "darkening" at one end... I'll try to get a picture... I realize this would be extremely difficult to replace due to the alignment required, but is it even possible to remove the flex PCB from the glass without damaging the glass?

[mp3car]

Re: Sharp LC-52LE640U - DET_PNL12V failure

definitely the flexible pcb... Impossible to purchase/replace?

[newtothis]

Re: Sharp LC-52LE640U - DET_PNL12V failure

For the average user the answer is no.

There are pulse tab bonding machines that attach COF etc but they are expensive!