Sharp LC-80LE844U Blinks 2 slow, 5 fast

[joblo37pam]

It's been a while since I've checked in here or needed input on narrowing down what to replace on a TV repair, but I've got one on my bench now that has me wondering. The lack of part (board) availability means I may need to do some component-level diagnostics, and a second opinion is always good when it comes to that.

The issue - Sharp LC-80LE844U does not display. Power light comes on for a while, then you can hear a relay click off and the light blinks twice slow, then five times fast. Service manual points to 'Panel Power Supply Error' with this code, but isn't much more help than that.

My first assumption was that some LEDs shorted, or the LED drivers on the power supply were bad. When I pull the cover off, I see no visible damage, and my LED tester lights up the strips individually (though the pinouts printed on the power supply board are not completely accurate).

I thought maybe the power output to the TCON was bad but it checks out right at the expected 12V until the relay clicks off and the error code starts blinking.

Here's where things get fuzzy - I disconnected the ribbon cables from the TCON to the panel to see what would happen. LED's light up and power light stays on steady - progress. I then started reconnecting the ribbon cables one by one and found that when the three left-most cables are connected, the TV powers on, LEDs light, and I get different display patterns based on which cables are connected. However, if the right-most cable (SC5301) is connected, I get no LEDs and the same blink code/symptoms regardless of what other cables are connected.

That's all good information, but I'm still unsure as to the resolution. My options:

- LED Strips - Not likely the issue, since I have tested them and they light normally when panel is disconnected from TCON
- Power board - Voltages appear to check out, but maybe a current supply issue? Not likely, but not unheard of. I don't see any availability, so component level troubleshooting would be necessary.
- TCON board - this is the one part I found with actual stock availability, but I'm not sure that replacing it is the answer. Is it worth ordering one to try?
- Panel - This is the direction I'm leaning. Unfortunate, since replacing them is never feasible, but the fact that connecting one section of it to the TCON causes failure suggests that there might be a short/defect in the panel.

So, after all of that I'm interested to hear some opinions about what to do next. If there's much confidence that replacing the TCON board will solve the issue, I'll order one, but based on the behavior with the last ribbon cable disconnected, my own confidence is low that will resolve it. What say you?

Thanks in advance.

[nomoresonys]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

That seems like panel issue, check this thread, this procedure should only be done after verification as it's permanent and can not be undone: https://www.badcaps.net/forum/showth...ht=freakafter8

[EazyBone]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

Sounds like panel also. Error goes away when ribbon is disconnected and usually that's panel. Google fixing TV with tape (yes scotch or masking tape) and watch the video. It has you tape off some lvds pins and if it works, you usually get your answer. Then maybe consider whatever Sony is talking about. I checked that thread and it had 51 pages lol, I ain't reading that.

[joblo37pam]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

I glanced through the thread, but not in full detail. That all looks fairly similar, but obviously for different models, so the mosfets mentioned don't apply and none of the mosfets on this board appear to be burned or test poorly in-circuit.

Based on what I saw there, I did see a post or video (can't find it again now) where they were able to diagnose the panel by testing resistance at the tcon board. I can't seem to find any comparable documentation for this panel, though. I'd like to do that before I order a tcon board to test. Any guesses as to where I can find a test point and what it should read?

[lotas]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

First, you need to inspect and check the non-working buffer strip of the panel for a short circuit of ceramic capacitors and protective diodes, if any, and then judge the panel itself.

[nomoresonys]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

Good advice Lotus.

[nomoresonys]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

I glanced through the thread, but not in full detail. That all looks fairly similar, but obviously for different models, so the mosfets mentioned don't apply and none of the mosfets on this board appear to be burned or test poorly in-circuit.

Based on what I saw there, I did see a post or video (can't find it again now) where they were able to diagnose the panel by testing resistance at the tcon board. I can't seem to find any comparable documentation for this panel, though. I'd like to do that before I order a tcon board to test. Any guesses as to where I can find a test point and what it should read?

.

[nomoresonys]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

Sounds like panel also. Error goes away when ribbon is disconnected and usually that's panel. Google fixing TV with tape (yes scotch or masking tape) and watch the video. It has you tape off some lvds pins and if it works, you usually get your answer. Then maybe consider whatever Sony is talking about. I checked that thread and it had 51 pages lol, I ain't reading that.

I have read every post in the thread, you need to read to gain knowledge. Those old pros like Freakafter8 and others, some of which have posted here, pretty much INVENTED all these fixes including the tape trick many years ago.

[nomoresonys]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

That seems like panel issue, check this thread, this procedure should only be done after verification as it's permanent and can not be undone: https://www.badcaps.net/forum/showth...ht=freakafter8

This IS the wrong advise for you, although these tv's were made around the same year, they are built differently with a slightly different design.

[EazyBone]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

I read a lot of advice, and lots of posts. Why you think I'm in this post. The tape isn't the "fix" for me. It's just a fast way to learn if my panel is bad. It's like a LED tester for backlights. Itd be dumb to take apart the whole TV to test backlights when I can stick couple probes on the line.

[Davi.p]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

post the power supply board (psb) code and test it at bench especially 12v tcon out, with dummy loads obviously, and with enabling signals

[joblo37pam]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

I was able to devote a little more time to this today hoping to narrow down the problem. I used the tape trick to try to isolate where the issue is. Turns out that as long as pin 72 (9th from right edge of ribbon cable when looking at contact side) is covered, the TV powers up. Looks like crap (odd colors/saturation and focus) on the left half, but it operates.

To me, this strongly indicates that it is a panel/buffer board issue, but I suppose there is still a possibility of a circuit issue on the tcon that is hidden when there is no load.

I'm going to try to get access to the buffer strips, but if I have to lift the panel out to get to them, I have low confidence that I'd get that behemoth out without cracking it.

[joblo37pam]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

Update - I couldn't walk away from it...Don't those type of projects just drive you nuts?

I got the frame separated and can get to the buffer strips without as much hassle as I expected. Visual inspection looks fine. I traced the line connected to the pin I covered up on the ribbon cable. It looks like it traces directly to one of the ribbons connected to the panel. No components that I could potentially replace. So we're down to the physical panel or the unlikely tcon board.

It kind of bugs me to put this much time into a project that will likely be unfixable, but experience is worth something, I guess...

[EazyBone]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

I know what you mean lol. I can't walk away from tvs like that also. Did you check all the caps though for shorted ones? That would keep your train going.

I mean the error code says panel, and you find a shorted pin so.. sell the boards and move on. Sometimes if I tape let's say 6-10 pins instead of just the shorted pin, you can get an okayish picture. Can try that ����

[Davi.p]

Re: Sharp LC-80LE844U Blinks 2 slow, 5 fast

the board pic i have already seen, i would test better that pnl_12v