Sharp LC-60LE600U Won't turn on

[theojt]

Original Owner said they used it about 25-30 times and then it just wouldn't turn on anymore, no other information.

When I plug it in, the chevron LED will come on for a few seconds and then go out. I do see a very brief flash of the backlights.

I have 5V BU (see all voltages below) on Pin 15 and I have 2.2V AC_DET on Pin 13. Everything else on the Power Supply "PD" 24-pin connector reads zero or very close to it.

If I disconnect the LED connector from the Power Supply (top edge of PS board) and perform a Reset, then I see all voltages for connector PD as recorded below (and I noted that AC_DET was slightly higher than it was before). These voltages are present for about 20 seconds, then the chevron LED begins a steady 1 second blink and the power supply shuts down. If I attempt a Reset with the LED leads connected, nothing happens. I have not observed any blink codes other than the steady 1 second blinking chevron.

I attempted to read the resistance of the LED strips but my DVM probes are too big to get into the small pockets on the connector, I'll address that tomorrow.

I'm thinking the Power Supply is probably good since I see all the required voltages before it shuts down (and I didn't find any diodes that were bad and all the electrolytic caps also read good with an ESR meter).

With LED connector removed, before the PS shuts down, I read the following on the PD connector (on the right-hand edge of the PS board)

Pin 1 PNL12V = 12.1V
Pin 2 PNL12V = 12.1V
Pin 3 SGND
Pin 4 SGND
Pin 5 UR13.2V = 13.2V
Pin 6 UR13.2V = 13.2V
Pin 7
Pin 8
Pin 9 SGND
Pin 10 SGND
Pin 11 SGND
Pin 12 SGND
Pin 13 AC_DET = 3.3V
Pin 14 PS_ON = 2.1V
Pin 15 BU5V = 5.0V
Pin 16 PNL_POW = 3.3V
Pin 17 PWM1 = 3.2V
Pin 18
Pin 19 DIMMER = 0.0V
Pin 20
Pin 21
Pin 22 ERROR = 3.2V
Pin 23
Pin 24 STB = 3.2V

Looking for concurrence that the PS is good, and any advice on what/how to check next.

TIA!

[budm]

Re: Sharp LC-60LE600U Won't turn on

Where are the Voltages reading for pin 21 OFL (bl-on), pin 23 PWM2?

[budwich]

Re: Sharp LC-60LE600U Won't turn on

as a "quick test", you might consider unplugging one of the tcon to panel cables, with power off (with everything else plugged in) and power up and see what happens... display? response? Do the same with the other side cable? any difference? Depending on the outcome, might save you a lot of time.

[theojt]

Re: Sharp LC-60LE600U Won't turn on

budm: Sorry, I should have mentioned - those pins are not present on my board (see photo of connector).

budwich - I started with one side, noticed no change; will do the other today.

.

[maxvalutech]

Re: Sharp LC-60LE600U Won't turn on

I think I would try to force the backlights on with main disconnected. This would probably require force PS on first. What does budm think about the voltage on pin for PNL on (panel backlights ? ) and Dimmer ?

[budm]

Re: Sharp LC-60LE600U Won't turn on

OK, I just look through my notes: STB = BL-ON, the 'OFL' pin is not BL-ON.
So from the look of it you do have all the correct command Voltages but I still need to look for my notes on the pin 22 ERROR pin to see if HIGH = NORMAL or HIGH = bad.

[theojt]

Re: Sharp LC-60LE600U Won't turn on

I think I found your reference (budm) at https://www.badcaps.net/forum/showth...t=59988&page=2

Check your post #24.

My problem, is that they all go away after a few seconds. I'll collect resistance readings on the LED connector tomorrow. I also found the Service Manual (attached).

[budm]

Re: Sharp LC-60LE600U Won't turn on

So all the Voltages are normal.

[theojt]

Re: Sharp LC-60LE600U Won't turn on

Yep, for a brief period of time when the backlights aren't connected and a Reset has been performed.

[theojt]

Re: Sharp LC-60LE600U Won't turn on

I measured the resistance with the LED connector (top edge of PS) plugged in as well as the peak voltage before the PS shutdown. Below are the readings:

Resistance
Pin 1 = 97.4K
Pin 3 = OL
Pin 5 = 97.5K
Pin 7 = OL
Pin 9 = 67.4K
Pin 11 = OL
Pin 13 = 66.6K
Pin 15 = OL
Pin 2,4,6,8,10,12,14 = NC

Peak Voltage (Note: Each pins voltage dropped to less than 1v very quickly after plugging in the TV)
Pin 1 = 85V
Pin 3 =
Pin 5 = 85V
Pin 7 =
Pin 9 = 77V
Pin 11 =
Pin 13 = 85V
Pin 15 =
Pin 2,4,6,8,10,12,14 = NC

So it looks like it may be bad LED(s) on the strip connected to Pin 9.

More observations:

If I disconnect the left panel connector from the TCON (see pic attached) and the LED connector is unplugged, the TV stays energized (I waited several minutes and then shut it off). Pin22 seems unstable this way though - I noticed it jumping between 1.8-2.4 but I'm guessing that it may be turning fully On & Off and I just don't see that. Disconnecting the right TCON connector didn't seem to have any effect. But if both are disconnected and the LED strips are connected, the Power Supply shuts down.

Also, if I plug in the LED connector and leave the left TCON panel connection off, then I see the right 1/2 of the screen light up (raster, no signal but bright and even) before the PS shuts down.

It appears I have a bad TCON board. I may also have a bad LED strip but I'm not sure. The resistance seems in line since I read somewhere that there are short and long strips in this TV (that would account for the 97K vs. 67K readings) but the 77V peak seems to be an anomaly. When both TCON connectors are plugged in, and I see the backlights flash on briefly, there is a dark area about 1/3 of the way in from the left edge. That could be nothing or it could be a bad LED/strip.

I guess I need to get a TCON and then see what that yields before tearing down the set to get to the LEDs (I want to avoid that).


Any other suggestions or tests anyone can suggest? Anything I overlooked before ordering a TCON board?

TIA.