Sharp LC-42SV49U No Power

[trwilson70]

Received yesterday and haven't spent much time on it. Near power input are 4 fuses - all are blown. Caps seem to be OK - my Blue ESR has a weak battery, too many read 000. Will check later with meter for direct shorts. Measured fuses with ohmeter and then hooked 120v - no power. Attached two shots of front of power supply and the back. Have not looked at input main board. Ideas?

[tom66]

Re: Sharp LC-42SV49U No Power

Check for the presence of a 5V output on the power board, a 5V standby rail.

[trwilson70]

Re: Sharp LC-42SV49U No Power

No DC, 4 fuses on input line are all bad, so no AC on the primary side.

[budm]

Re: Sharp LC-42SV49U No Power

Was the TV hit by power surge or lightings?

[trwilson70]

Re: Sharp LC-42SV49U No Power

I don't know the history of it - the back had been off, the PS had some screws missing. With the fuses bad on the input, I wondered about a power surge - seems odd that all four fuses would be out and yet nothing else on the board appears smoked. What I am trying to decide is how much time and $ to put into it. Haven't looked at input board yet to see if there is damage there.

[trwilson70]

Re: Sharp LC-42SV49U No Power

OK - jumpered across two fuses - installed a couple of 5a slow blow on the other 2. Touched with 120v and fuses immediately blew.

[budm]

Re: Sharp LC-42SV49U No Power

https://www.badcaps.net/forum/attach...1&d=1411074630
What is that white jumper installed across the Hot and the Neutral line? That is a dead short.

[Josephmichael09]

Re: Sharp LC-42SV49U No Power

I have the same tv that has no power(except stand by power) I did not find any fuses on the power supply board. Unless the little yellow/tan-ish rectangles are fuses.

When plugged in the stand by led turns on. When I try to power on the tv, the led turns off and remains off. Nothing happens.

From the power supply there are 3 connectors. Two go to the main board and the other to the power inverter.
I was takin measurements from one of the connectors the go to the main board. The colors on the connector are black, red, orange, brown, yellow, and green.

With the power cord connected the only voltage u get is 5.2v coming from the orange pin(which I believe to be stand by voltage). When I press the power button, the stand by voltage fluctuates then returns to 5.2 volts. There is still no voltage at the other pins and the stand by voltage does not drop to zero.

The caps look ok. I am going to change them either way but, are there any suggestions as to what's wrong?

[trwilson70]

Re: Sharp LC-42SV49U No Power

OK - finally had time to get back to work on this.
budm - doh, you are so right. I saw that, looked at component on other side, looked up number and it said it was a relay - so perhaps the jumper was needed - further reading called it a capacitor?? What are they, there are 2! Someone else added the jumper - was I set up to fail?
Was able to get another power supply and now have 5v out to input board - but still no indication of power on. Help with next step? Will get photos of input board later today - haven't traced where the 5v goes.
Josephmichael09 - where the power connects there are 4 small tan/brown rectangles are the fuses - 5a I think.

[budm]

Re: Sharp LC-42SV49U No Power

That jumper is put in place of the AC Line noise filter cap which is connected between Line and Neutral, big NO NO.
'was I set up to fail?" yes!
So photo of the back side of the TV so I can see how they are connected together. The question is, did the person do something stupid and dangerous on the other boards and wirings too?

[trwilson70]

Re: Sharp LC-42SV49U No Power

Not as clear as I had hoped, done with my phone because that is what I have handy.
I don't see anything real obvious - just now checking a few more things.