Sharp LC-80LE661U - Power's off after 4 seconds.

[nomoresonys]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

Make sure you are identifying your pins correctly, you should have around 0 volts on the ground pins.

[overlyAmbitiousSloth]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

Yes you can usually jumper the powerboard pins they suggest using a resister in case you get the wrong combo, make sure the connector cable between mainboard and powerboard is unplugged when doing this test.

I see the following labels on the pin label for the cable between the mainboard and the powerboard:

PNL12V
GND
UR13.2V
UR13.2V
GND
GND
PS_ON
PNL_POW
NC
NC
ERROR
STB

Would it be the PNL_POW pin that I need to short to ground?

When taking power readings earlier I saw 5V on that pin. What type of resister would I need to use? Or, could I short it directly to one of the GND pins above (was seeing 4.5V on the two ground pins 5th and 6th from the top)?

[nomoresonys]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

Yes you can usually jumper the powerboard pins they suggest using a resister in case you get the wrong combo, make sure the connector cable between mainboard and powerboard is unplugged when doing this test.

[overlyAmbitiousSloth]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

Try unplug tv from power outlet, disconnect cable from mainboard to powerboard, plug power cord back in turn it on, see if backlights come on and stay on.

Tried but didn't turn on when I applied power. This may be a stupid question but is there a pin on the powerboard I can short to ground or something to feed it a 'power on' signal?

In addition to those tests, you can try disconnecting the tcon to panel cables, one at a time, and see if that changes the results (of course the disconnect / connect is done without power on).

When I disconnected the large ribbon cables, one at a time, and powered on half of the screen was solid white (pictures attached).

For shits and grins I started disconnecting different cables, one at a time, and powering back on. Wifi, IR receiver, speakers, button pad, data cable from main board to tcon, all didn't make any difference (well the last one stopped Sharp from displaying). Then I pulled the power cable to the tcon board and noticed the standby light flashing at longer intervals. Its not like a dot-dot-dash sequence or anything just longer dashes, if that makes sense. Was kind of expecting an error code when a main component is missing / not getting power. Is that normal?


Anyway, thanks for the suggestions guys and please keep em coming.





PS - It looks like there's an RS232 console port on the side of the mainboard. Does anyone know anything about that? I don't have a female to female serial cable or I would trying connecting to it. Being that it only powers on for a few seconds I doubt I'd be able to do much aside from maybe a receive a quick dump of a POST or something.

[overlyAmbitiousSloth]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

first guess would be main board.

Is that a common symptom of a dead/dying main board? If so, is it even worth troubleshooting components on the board or just replace the whole thing?

In addition to those tests, you can try disconnecting the tcon to panel cables, one at a time, and see if that changes the results (of course the disconnect / connect is done without power on).

Thanks for the suggestion budwich, I'll give this a shot as soon as I get home this evening and check back in with results.

Try unplug tv from power outlet, disconnect cable from mainboard to powerboard, plug power cord back in turn it on, see if backlights come on and stay on.

Thanks for the suggestion nomoresonys, I'll give this a shot as soon as I get home this evening and check back in with results.

[overlyAmbitiousSloth]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

You need to put down the pin name for each pin and follow by the Voltage reading so we can easily see what each pin is.

My bad, didn't even think to do that (I've attached a picture of the power board that lists pin names, not sure if I'm reading it properly but I've referenced the PIN names in the left column)-

TV OFF/Stand-By
PNL12V - 0.3v
GND - 0
UR13.2V - 1.214v
UR13.2V - 1.213v
GND - 0
GND - 0
AC_DET - 0
BU5V - 5.04v
PWM1 - 0
DIM - 6.4v
OFL - 0
PWM2 - 0

TV ON – power applied
PNL12V - 11.88
GND - 3.8
UR13.2V - 13.12
UR13.2V - 13.14
GND - 4.5
GND - 4.5
AC_DET - 3.331
BU5V - 5.03
PWM1 -1.427
DIM - 1.294
OFL - 1.427
PWM2 - 1.427

[nomoresonys]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

Try unplug tv from power outlet, disconnect cable from mainboard to powerboard, plug power cord back in turn it on, see if backlights come on and stay on.

[budwich]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

In addition to those tests, you can try disconnecting the tcon to panel cables, one at a time, and see if that changes the results (of course the disconnect / connect is done without power on).

[budm]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

You need to put down the pin name for each pin and follow by the Voltage reading so we can easily see what each pin is.

[ajshoe]

Re: Sharp LC-80LE661U - Power's off after 4 seconds.

first guess would be main board.

[overlyAmbitiousSloth]

Howdy Folks,
This is my first time posting with an issue so I'm including as much info as I can (whether it turns out useful or not). I don't have any experience troubleshooting LCD TV's so I'm hoping someone out there can give me some tips or maybe point me in the right direction (even if its a 'RTFM nuub' if there's a link attached).

I've got a Sharp LC-80LE661U model TV that powers on, displays the SHARP logo and then promptly turns off after about 4 seconds. There isn't anything displayed onscreen other than the logo. I've tried button combinations to perform a factory reset, I've tried opening menu's as soon as it powers on, I've tried different video inputs... but I never see anything other than the Sharp logo. And then the screen flashes for a split second and shuts down.

Once it powers down I see the standby light illuminate on a steady interval (unfortunately, no error code is being passed).


Popping the thing open I see what you would expect, power board, processor board and a t-con board. I know nothing about troubleshooting these guys so I took a close look at each and am not seeing what looks like failed components (at least nothing crispy, bulging or leaking). Then I busted out the volt meter and the readings I'm getting, I think, don't sound waaay off (at least based on what was printed on the power board).


Power board is a RUNTKB380WJQZ and I'll include a shot of what the voltages should be based on whats referenced on the PCD.

TV OFF - power applied

1- 0.3v
2- 0
3- 1.214v
4- 1.213v
5- 0
6- 0
7- 0
8- 5.04v
9- 0
10- 6.4v
11- 0
12- 0

TV ON – power applied

1 - 11.88
2 - 3.8
3 - 13.12
4 - 13.14
5 - 4.5
6 - 4.5
7 - 3.331
8 - 5.03
9 -1.427
10 - 1.294
11 - 1.427
12 - 1.427


Not sure where to go from here. I hate throwing parts at a problem until its fixed so any advice would be more then appreciated.

Thanks Folks,
Jon