Sharp Aquos 80" not working

[Markus66]

Hey,

So, I purchased this TV new about 3 1/2 years ago - not long before FutureShop closed... It's in the basement and doesn't get used much but having said that I have never had a problem with it until the last couple weeks.

First sign of trouble was a couple weeks ago when I got two long flashes and three short flashes on the front power indicator LED. A little research and I was able to clear the error with the channel down/volume up while plugging in method. The TV would then work like normal. I had to do this a couple times over a couple days. I didn't use the TV for a week or so then ran into the same error a couple days ago. Trying the channel down/volume up would "clear" the error and give me a solid power LED but, the TV would not actually work this time.

I found this site and read through the half dozen or so threads pertaining to this model and issue/similar issues, and did some testing. What I found was this...

5VDC present at power supply

3 VDC present from main board to power supply only after resetting TV with Channel down/volume up. Otherwise no 3 VDC present when flashing error mode.

No 12VDC/13 Volt present at any time.

I have played around with all the connectors/harnesses and powered up and down with all different variations of connections. There is no change to the operation of the TV with or without the T-Con board or it's ribbon cables attached.

Because the main board is sending a 3 volt signal to the power board, I have to assume at least in part that the main board is doing it's job on start up.

I don't have schematics for the power supply board and I'm not sure I would be able to decipher them anyhow as there are a few fancy chips surface mounted on the back side. After messing around with the TV for a good chunk of yesterday, I feel fairly confident that it is a power board issue and it centers around the 12V portion of the board. There doesn't seem to be any of these boards in stock in North America at this time - there are a couple in the UK for the far side of $500 which I feel is ridiculous. I'm ok with attempting a repair if I need to - although a board swap would definitely be simpler.

I went over the power board with a light and magnifying glass and can see nothing obvious - no burns or discoloration, no broken traces, no caps let go etc.

I'm going to attempt to attach a picture of the board showing the model number and layout to this post.

Any advice is welcome - or any knowledge of the whereabouts of a replacement board would be appreciated.

Power board ID RUNTKA903WJQZ

[dick_barton]

Re: Sharp Aquos 80" not working

It's useful if you could list the names on the power to mainboard connector alongside the voltage read when in standby and when you attempt to bring it out of standby. Something similar to the following (taken from a different set) would be helpful.

When you were clearing the Error what Error was it?

[Markus66]

Re: Sharp Aquos 80" not working

Error was two long and three short and has not varied from that.
As far as I can tell that is a power supply error.

Voltages:

Pin 15 +5.12 VDC always
Pin 13 +3.29 VDC only when not flashing error code.................................... 0.00 VDC when error code flashing

Pin 14 +2.84 VDC as measured at J7578 only when not flashing error code..... 0.00 VDC when error code flashing
I hope I've traced pin 14 correctly to a top side jumper...

No voltages present on any other accessible pins (top row), at any time.


Thanks,
Mark

[dick_barton]

Re: Sharp Aquos 80" not working

Hello Mark
You have around 24 to 28 pins on connect PD and each will have a name as shown in the red box. The lower pins of PD can be read either by testing each pin on the underneath of the circuit board or push a pin alongside the grey wire going into the connector.

[budm]

Re: Sharp Aquos 80" not working

What is the model number of this TV?
'two long flashes and three short flashes' that is D 3.3V power supply error.

[Markus66]

Re: Sharp Aquos 80" not working

dick - will check the rest of the bottom side pins when I get a minute - I'm going to Ohm them out with the corresponding top side pin as it looks that most of them may actually be connected to each other with one or two exceptions.

bud - Model is LC-80LE632U Sorry. Should have included that in the original post.

Thanks,
Mark

[Markus66]

Re: Sharp Aquos 80" not working

Complete voltage readings...

[budm]

Re: Sharp Aquos 80" not working

You have PS-ON (2.84VDC) present but the switched 13V does not come on.
Check the DC Voltage right at the two legs of the main filter cap C7220 to see if you do have about 380VDC while PS-ON is present.
BTW, you are 100% sure that the error code is 2 longs and 3 shorts, not 5 shorts, correct?

[Markus66]

Re: Sharp Aquos 80" not working

I'm getting 165 DC volts at the filter caps...

Correct, 2 long - 3 short

[budm]

Re: Sharp Aquos 80" not working

Well, the PS-ON is present but the PFC Voltage booster circuit does not come on, this will require in-depth troubleshooting without having the schematic diagram, so it will be very time consuming.

[Markus66]

Re: Sharp Aquos 80" not working

I couldn't find any schematics online at all. That stinks.

[dick_barton]

Re: Sharp Aquos 80" not working

There's a relay on the power supply (RL7203). Can you hear it click when you power up out of standby?

What is the part number as written on IC7102 & IC7203

What resistance is R7217 and does it match what's written on it.

Photo's courtesy Shopjimmy

[dick_barton]

Re: Sharp Aquos 80" not working

Also with your set off (disconnected from the wall socket) and multimeter set to ohms check ICP7201 which looks as though it's a semiconductor fuse (in circuit protection = ICP) and also resistors R7273 and R2774.
It may be that Q7208 and or Q7209 may be faulty and again these can be checked while the set is off using your meter set to diode mode.

[Markus66]

Re: Sharp Aquos 80" not working

There's a relay on the power supply (RL7203). Can you hear it click when you power up out of standby?

What is the part number as written on IC7102 & IC7203

What resistance is R7217 and does it match what's written on it.

Photo's courtesy Shopjimmy

1. Yes, you can clearly hear the relay upon startup

2. See attached pictures.

3. D7109 OK
D7110 .642 / 1.7
D7111 .493 / 1.99
D7112 TESTS SHORTED forward and reverse
D7114 OK

4. R7217 is a 3W 15Mohm. I'm not getting a resistance reading in circuit. I'm guessing I will have to desolder to check properly?

[Markus66]

Re: Sharp Aquos 80" not working

Also with your set off (disconnected from the wall socket) and multimeter set to ohms check ICP7201 which looks as though it's a semiconductor fuse (in circuit protection = ICP) and also resistors R7273 and R2774.
It may be that Q7208 and or Q7209 may be faulty and again these can be checked while the set is off using your meter set to diode mode.

ICP7201 shows continuity while in circuit

R7273 and R7274 are showing continuity as well - clip/desolder to properly test?

Q7208 and Q7209 Both check good. 0.488 between S and D on both. Open in reverse.

[dick_barton]

Re: Sharp Aquos 80" not working

Best to lift one end of D7112 to check if still short circuit.

[Markus66]

Re: Sharp Aquos 80" not working

Best to lift one end of D7112 to check if still short circuit.

Will do. Have a bunch of company coming over soon so, I will have to pause this until tomorrow when I have time to dig out my soldering iron and get back to it.

Thanks for the spec sheets!

[budm]

Re: Sharp Aquos 80" not working

D7112 is the snubber didode for the standby power supply section, it is connected in parallel with the primary winding if the standby power supply transformer that is why it shows low Ohms resistance. I would not look into the standby power suply section because it is working and you do have the standby Voltage.
Check the RESISTANCE of PFC Diode D7209 .
P/ of 7201?

[Markus66]

Re: Sharp Aquos 80" not working

D7112 is the snubber didode for the standby power supply section, it is connected in parallel with the primary winding if the standby power supply transformer that is why it shows low Ohms resistance. I would not look into the standby power suply section because it is working and you do have the standby Voltage.
Check the RESISTANCE of PFC Diode D7209 .
P/ of 7201?

Had a few minutes to revisit this board.

1. D7209 shows 62KOhms. 387KOhms in reverse.

2. I am unsure of what you are asking me to check/measure [ P/ of 7201]
Is that primary winding of the little 7201 transformer? If so, reads continuity (0.1 Ohms).


Thanks,
Mark

[budm]

Re: Sharp Aquos 80" not working

Sorry, I mean IC7201 in the hot side of the circuit.