Sharp LC-90LE745U 3 slow and 1 fast Blink

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

It looks like Q2603 supplies power to IC 2601. It is labeled to have 3.3V on the emitter and 3.2V on the collector as seen on the schematic on page 14 of the service manual - attached as zip file. Perhaps the HDMI chip is blown loading it and also causing the low ohm readings. The real test would be to check the voltages.

Hopefully, this is encouraging and you just got a bad board to replace your bad board, and the new one in the mail might work.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

it depends... its the standby pin... IF its not in standby, then its likely to be 0.

Ah ok. when I plugged in. The ps-on has 3v. Just the pnl-pow is not getting 3v from the main board. So it might not be in standby. If I remember. The voltage on the big caps jumps from 130v to 300++

We'll see next week when the replacement board comes in. If it's still doing the same thing then we'll see hahaha. Can't find any power supply board replacement anymore.

Thank you

[budwich]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Does pin 24 should not be 0v?

it depends... its the standby pin... IF its not in standby, then its likely to be 0.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Here's the pic of the main board and the area of the component that is getting hot. It seems that area is responsible for the HDMI out area.

Will take the pic of the whole setup when I open it up again next week.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

I think you need to jump it to PS-ON not PN-POW. This turns the power supply on. You should get backlights on and other voltages... all pins should be measured and checked.

It doesn't sound good about the hot component and "0" volts ... but it may be what's connected to that area and not that component ... ie. there is a short in the output / destination... which likely might be towards that panel or tcon itself. You need to posts pictures of the whole backside to show how things are connected and then closeups of the area in question.

Does pin 24 should not be 0v?

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Will jump 5V to PS-ON (Pin 14) when I open it up again next week and will measure all voltages.

Jumping 5v to PS-ON, back light should come on?

[budwich]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

I think you need to jump it to PS-ON not PN-POW. This turns the power supply on. You should get backlights on and other voltages... all pins should be measured and checked.

It doesn't sound good about the hot component and "0" volts ... but it may be what's connected to that area and not that component ... ie. there is a short in the output / destination... which likely might be towards that panel or tcon itself. You need to posts pictures of the whole backside to show how things are connected and then closeups of the area in question.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Forgot to mention. When I install the ordered main board. One component is really getting hot to touch as in you will get burned. Measuring the temp with a laser temp. It goes from 27c then increase to 45c and up. It’s q2603 transistor. And measuring the pins. I’m getting 0 ohms which tells me shorted. So I’m suspecting the main board might not be working either. I contacted the store and requested a replacement. It should arrive next week and crossing fingers it’s the main board lol. ��

Then will contact them to return the other board after.

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

From reads herein, I think that you can disconnect the main from the power board and then jumper the ps-on pin thru a resistor to 5v pin to turn the power supply on. The backlights should also come on. go from the results, and do some measurements thereafter.

Thanks for the reply. Tried to jumper from the 5v to pin 14 and pin 16 (pn-pow). I was able to get 12v on pin 1 and 2

[c00lman]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Have you tried the reset?

Hold Vol+ and Ch- while plugging it in?

Curious about the SB pin #24 also, was that low with both Main boards?

Yeah. Tried to reset but not getting it to display anything

Would the reset works even if the board is dead? Or will it only work if the main board is still working?
Pin 24 is 0 on both boards

[budwich]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

From reads herein, I think that you can disconnect the main from the power board and then jumper the ps-on pin thru a resistor to 5v pin to turn the power supply on. The backlights should also come on. go from the results, and do some measurements thereafter.

[RDC55]

Re: Sharp LC-90LE745U 3 slow and 1 fast Blink

Have you tried the reset?

Hold Vol+ and Ch- while plugging it in?

Curious about the SB pin #24 also, was that low with both Main boards?

[c00lman]

hi, new member her and apologize if this has been discussed.. tried to search and most of the result are for LC-xxLe6xx series and not sure if it's applicable to the 745U.

the TV stopped turning on and after the V logo stayed solid for a minute or 2, it gives the 3 slow and 1 fast blinks which from what I researched are internal communication error.

did some voltage measurement on the power supply out.
Pin 1 and 2 = 0V --> PNL 12V
Pin 3 and 4 = 0 V --> GND
Pin 5 to 8 = 13V --> UR 13V
Pin 9 to 12 = 0 V --> GND
PIN 13 = 3.24 V --> AC_DET
Pin 14 = 3.01V --> PS_ON
Pin 15 = 5.04V --> BU5V
Pin 16 = 0V --> PNL_POW
Pin 17 to 21 = 0V
Pin 22 = 3.24 = ERROR
Pin 23 = 0V
Pin 24 = 0V

from what I read on the other thread on this forum, the power supply will not turn on the PNL12V if there's no power on PNL_POW pin (correct?)

I measured the voltages on the big caps and they are 164V then jumps to 300++V.

Also the power supply clicks when plugged in.

thinking it's the main board as there's no PNL_POW, ordered it last week and just arrived today. plugged the replacement main board and no changes on the symptoms, plugged in and after few minutes, it does the 3-1 Blink.

both main board does not blink either (The LED on the main board).

What other test can I do to isolate if it's power supply or if the main board that arrived is bad. I understand that the TV is few years old and we will not be able to order new boards.

or is it time to say goodbye to it?

Attached are some pics of the the power supply

please and thank you in advance.