Sharp LC70UQ17U won't power on - 3 long blinks, one short

[dougdon]

Hi everyone,

Having some difficulties with my 70" Sharp TV purchased around 3 years ago. Model number is LC70UQ17U. Around a month ago the image on the tv occasionally started flickering pretty severely:

https://www.youtube.com/watch?v=DXkY-qXxCNU

If you restarted the TV the problem would go away. Around a week after it first started, however, the TV shut off while we were watching it and it won't turn back on. The front light blinks in the same pattern repeatedly -- three long blinks, pause, one short blink. Based on some research I did it sounded like it might be the power supply board, so I tried replacing it but it didn't work, still have the same blinking pattern. Then I thought the replacement part I had been shipped may have been defective, so I ordered another new one and it didn't work either.

Someone pointed me to the service manual, and they found this:

https://imgur.com/a/ln7y0

Anyone knows how I'd go about fixing this, or if it's fixable? Thanks a lot

[dougdon]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

Here are the various boards in the TV

[tom66]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

A communication error on a Sharp set in most cases would indicate a main board fault. That is the first board in those pictures, the one with A/V inputs.

[dougdon]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

Thanks for the reply. So in your experience, if I replace the main board it should fix my problems?

[tom66]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

I have only fixed one before in another Sharp set, and it is possible there are other faults, but for a big 70" set I would have thought it is worth taking the chance. I have not looked up the cost of a main board, but you can usually find them for less than $100.

I would say about 80% chance it is the main board at fault.

[dougdon]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

Thanks, I'll give it a shot. Appreciate the info

[dougdon]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

Well, unfortunately that didn't work... swapped out the main board today, plugged in, hit power and after around a minute the front light started blinking the same pattern as before. Is there any factory reset/ firmware I would need to update in order to get around this error code?

Otherwise, any other ideas what might be causing the problem, and whether it can be fixed?

[tom66]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

Hmm, not sure unfortunately.

Small chance the board you got is defective if purchased used/second hand (most boards are, rare to find genuinely new ones.)

I guess there's a chance it's the T-con - 3rd picture in your first post - but I wouldn't think that as being very likely.

You could try a second main board (consider an exchange with seller?), or a T-con, up to you, but I do not know, sorry.

[budwich]

Re: Sharp LC70UQ17U won't power on - 3 long blinks, one short

you can also try unplugging one cable going from tcon to panel and see what the result is. Repeat the test doing the same with other cable. Some form of stable picture may result (half that is still plugged in). Go from there. Ensure your cabling between boards is well connected / clean contacts.