Another LC-80LE632U 2-5 thread

[jacksnife]

I picked up this TV hoping I might get lucky. I read all the 2-5 error code threads I could find, as well as some 1-1 and 2-3 error code threads and TIP-1541.

I do have some hope because it appears the T-con is shorting out the 12V lines. If I disconnect the 4 pin connector I have 12V sitting there (until the PS clicks and goes into shutdown). If during this time I connect the cable back to the Tcon the voltage drops to near 0V. So according to TIP1541 I should replace the Tcon board.

I don't mind buying all new boards, but I don't want to throw any good money at it without knowing the panel is good. I can't see any visible signs of damage... but I also do not get any backlight flashing or any sign of life coming from the screen. Is there anything I can do to trick the backlight on? Or any other things I can try that might make me feel confident the screen is ok?

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

I should probably mention I followed Tip1541 by removing the ribbon cables... there was no back light and the 2-5 code is still present.

[sordids999]

Re: Another LC-80LE632U 2-5 thread

Posting pictures of the back of your tv showing the boards with clear pictures may help you more with fixing your problem

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

Right now I would like to figure out how to turn on the backlight power... or maybe measure voltage at the pins to see if it's just plain dead? I can borrow an o-scope if needed. I need to try to see if there is any damage to the screen before I really put some time in on it. I looked at it in the sun and couldn't see anything obvious.

Are these backlights just simple LED's with constant voltage? Or is brightness controlled by duty cycle?

[freakaftr8]

Re: Another LC-80LE632U 2-5 thread

These sharp 80-inch panels are built very closely in relation to the 70-inch panels that are failure prone. You could attempt to try to power up the panel with one driver cable disconnected at a time at the secon and see if the TV comes up using the reset code Vol-+ and ch- while plugging it in. Once the backlight attempt to power on release all buttons.

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

Ok, holding all three buttons stops it from going to the 2-5 blink state. But I never see or hear any sign of a backlight.

I have .7V on the 12V pin of PD, then disconnect the 4-pin PL connector on the tcon board and the 12VDC comes back. i.e. the Tcon is either shorting out the 12VDC, or the power supply no longer can supply enough current to turn it on so the volts drop to near 0.

[freakaftr8]

Re: Another LC-80LE632U 2-5 thread

okay now disconnect both white flat ribbon cables going from the tcon to the panel in try the restart code again

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

Please correct me if I'm wrong, but in my mind the Backlight and the LCD Panel are two completely different animals. If the display was dead it wouldn't kill the backlight (and vice-versa) would it?

So right now I have the V light on constant (no error code), I have the Tcon 4-pin disconnected and 12VDC is up. Shouldn't I be able to read some voltage on the backlight connectors?

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

ok sorry I jumped the gun... I'll go do that.

[freakaftr8]

Re: Another LC-80LE632U 2-5 thread

Well you are correct they are two different systems however the t-con panel voltage is the first that the mainboard reads to make sure that all systems go if that system shorts out you will get no back lights. If it's a panel failure you will normally get 2- 5 error code

A 1-1 error is related to led backlight failures in Sharp

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

Same result, .7VDC sitting on the 12VDC with PL connected.

Also while I was there I decided to probe on the bank of transistors. I'm guessing they are for powering up the backlight and that there should be a rail voltage sitting on the Collector, Base being pulsed, and the actual LED sitting on the Emitter. 0VDC on all of them.

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

Well you are correct they are two different systems however the t-con panel voltage is the first that the mainboard reads to make sure that all systems go if that system shorts out you will get no back lights. If it's a panel failure you will normally get 2- 5 error code

A 1-1 error is related to led backlight failures in Sharp

Ok, thanks for the help...

So considering I have the display ribbon cables disconnected I can assume the display itself is no longer influencing the fact I still have a shorted 12V power at the Tcon. It doesn't mean the display is good... but I can't say for certain it is bad until I get a known good Tcon board, correct?

[freakaftr8]

Re: Another LC-80LE632U 2-5 thread

Possibly. You could try removing the power source to tcon and try reset code and probe tcon 12v output voltages and see if they briefly come up.

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

Ok, I assume the Tcon power source is the 4 pin connector (PL)? When it is disconnected there is 12V coming from the power supply sitting at the disconnected 4 pin connector. When I connect the 4 pin connector back to the Tcon board there is 0.7V.

"probe tcon 12v output voltages and see if they briefly come up" <- Are you referring to the power supply 12V output? Or does the Tcon also have a 12V output?

Man, schematics sure would be nice! If I just had a power supply schematic I know I could figure out a way to power up those backlight led's... without a Tcon or a main board even connected. I'd bet the main board is just sending discrete signals to it.

[dick_barton]

Re: Another LC-80LE632U 2-5 thread

Hello,
I would have thought that if the Tcon was taking down the 12v line that it would have blown the onboard fuse on the Tcon. Can you load up the 12V line when disconnected from the Tcon with resistors and check it is supplying reasonable current. Power supply problem?
Regards

[jacksnife]

Re: Another LC-80LE632U 2-5 thread

I was thinking the same thing... the Tcon board measures about 4 ohms between the +12V pin and gnd and is dropping the voltage to 0.7V. Is my thinking right for that 12V PS to only be sourcing 175mA?

I wouldn't mind spending a few bucks to get a spare, but i'd rather do everything I can to determine if the screen is good/bad before ordering one. I suppose the only thing I can do is visually look for physical damage, so this is why I want to rig the backlights to come on.

[budwich]

Re: Another LC-80LE632U 2-5 thread

you would be better off tracking / checking ALL the voltages "labeled" on the power supply. I doubt that the tcon is bad. More than likely you lost a section of the power supply... further check all diodes on the power supply as some have found ones to have been "broken". Once replaced, they are happy.

[dick_barton]

Re: Another LC-80LE632U 2-5 thread

I'd agree with budwich and take a real good look at the power supply. Check the fuse rating of the fuse on the Tcon and that should tell you what it expects in terms of current.

[budm]

Re: Another LC-80LE632U 2-5 thread

It this your exact power supply-LED driver board?
Sharp RUNTKA903WJN1 Power Supply LED Board.
http://www.shopjimmy.com/sharp-runtk...pply-unit.htm#