L42A403 Hitachi NO POWER - Fuse Good - Caps Good

[barryra]

I'm stumped on what would be the issue with no power, lights & no clicks with a Hitachi L42A403. I tested fuse & caps look good. Thanks

[budm]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Good clear Pictures of the back side of the TV, the boards? Any voltage testing?

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Hello, thanks for the response. There are 2 +12 V that measured 2.2.. the 2 24V measured .4

I sent you a PM.... thanks again

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Where it's listed 5V it measures 4.98. I didn't get anything on the 12 or 24 v this time. Maybe I did it wrong the last time.

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Where it's listed 5V it measures 4.98. I didn't get anything on the 12 or 24 v this time. Maybe I did it wrong the last time.

[budm]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

OK, the 12v, 24, and the PFC voltage booster are turn on by the main board, so lets see if we do have the PS_ON siganl and the PFC voltage is working or not first by checking the dc voltage right at the two legs of the big 450vdc caps laying on the side. When the TV is off, the voltage should be about 160~170vdc, and it should go up to about 370~390vdc when TV is switched on.
Please also post the voltage label of the connectors on the power supply board.

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

The 450v caps measured .2 on & off. Where are the measurements listed on the power board? Thank you

[budm]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

That cannot be the correct reading since the 5VDC power supply is also connected to those two caps, if those two caps has no voltage, you will not have the 5V either. What meter setting are you using?

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

I measured the 450v caps at .2 each on & off I attached a picture of the power board voltages.

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

I'm using 200 v dc reading

[budm]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Can I see the bottom side of the board?

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Sure... I don't see any burnt spots. Hopefully you see something I don't. Thanks

[budm]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Well I cannot see why you are not getting the 160vdc on the cap at all, from tracing the bottom side of the board, the 5VDC power supply is transformer is connected to those two cap positive legs of the two caps which it is using the power from after the AC is rectified by the bridge.

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

When will you be on here again? I better get some sleep. I'll check it again afte work tomorrow. I really appreciate you helping me with this.

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

I found out the tv repair shop had this tv before I did.. He thinks it has a bad main board. Wouldn't there be something lit up? It's dead.. no power light etc..

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Correction.. I searched the board number the repair shop thought was bad & it came up with the power board.

Hope to see you on tonight Budm

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Hi Budm.. I'm ready to do more testing if you are.

[barryra]

Re: L42A403 Hitachi NO POWER - Fuse Good - Caps Good

Budm.. would you have some time tonight to help me with this? Thanks