Sony KDL-46Z4500 Completly Dead

[max1636]

I've got a KDL-46Z4500 with what I believe to be a faulty power supply board. Part No. 1-877-271-12 I am getting no standby codes and no standby voltage and the pin on the main output connector. However when I unplug the T-Con board connector I get a very small reading less than a volt but I don't believe the T-con is faulty I just think it's trying to draw current but It can't.

I have some experience repairing TV's and really want to repair this board instead of just buying a new one. There are a few components I have tested or replaced from another working Sony board, which include:

- Main 150uf 450 Caps
- Bridge Rectifier
- Main Relay
- Standby Transformer
- 0.22uf and 10K Cap right beside the mains input
plus the other 0.22uf and 10K cap after the coil/choke things

I have also tested with my ESR meter all the caps beside the main output connector all measuring fine. The fuse is also fine.

[budm]

Re: Sony KDL-46Z4500 Completly Dead

Service manual:
http://elektrotanya.com/?q=showresul...oria=&kat2=all
What DC voltage do you get on that 150uF 450VDC?

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

Thanks! Service manual should come in handy. I hadn't checked the voltage on the main 450 Caps yet (There are actually 2, even though I've seen the same board with one) I found something very strange, the voltage very slowly climbs and after about a minute I only get about 0.5v DC. I will leave it plugged it for as long as I'm in the room with it and see what I get.

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

I thought I might of just been charging the caps with my DMM but after another few minutes I'm almost at a volt. So I guess the problem is whatever feeds those main caps?

[budm]

Re: Sony KDL-46Z4500 Completly Dead

I did not download the SCH for the TV yet to see if it just has simple bridge rectifier feeding the main cap or not, if it is that will be the first place to start. When TV is plugged in but not turn on, the DC voltage on the cap should be = AC line voltage x 1.414. When the TV is turn on, the PFC Voltage booster should kick the voltage up around 370~400VDC. Since you are working in the primary side of the circuit, the Ground ref point for the meter will be the negative leg of the Cap, not the chassis ground.

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

I just tested the bridge rectifier according to this video:
http://www.youtube.com/watch?v=dqkT6hF0O3E

It works just fine so where can I go from there?

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

I assume this is normal, but with no power to the board and my DMM on ohms. I get zero resistance from the negative of the bridge rectifier to the negative of both caps. But on the positive from the bridge rectifier to the positive of each cap I get about 9k Ohms. Is that unusual?

[selldoor]

Re: Sony KDL-46Z4500 Completly Dead

I assume this is normal, but with no power to the board and my DMM on ohms. I get zero resistance from the negative of the bridge rectifier to the negative of both caps. But on the positive from the bridge rectifier to the positive of each cap I get about 9k Ohms. Is that unusual?

I wouldnt have thought so - try unsoldering and resoldering the joints.

Pictures would help us know exactly what you are doing.

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

I appreciate the help.
This is what I'm measuring, negative from the rectifier to the two main 450v caps gives zero ohms, see images:
http://i1208.photobucket.com/albums/...ps3429774f.jpg

http://i1208.photobucket.com/albums/...ps77b72e3a.jpg

[tom66]

Re: Sony KDL-46Z4500 Completly Dead

Check for cracked solder joints, blown fuses, etc.

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

Check for cracked solder joints, blown fuses, etc.

The only fuse I can see on the board is the main fuse which is fine, do you know of any others on this board? I have reflowed most of the main joints as well with no luck do you have any other suggestions?

[tom66]

Re: Sony KDL-46Z4500 Completly Dead

Is there a relay on the board?

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

Is there a relay on the board?

Yes, and I've swapped it with another one and it's good.

[selldoor]

Re: Sony KDL-46Z4500 Completly Dead

Board pc is too fuzzy for troubleshooting please repost just the board both sides.
It is useful if you can post using manage attachment then in future the thread makes sense

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

Hi-Res Top Image Here:
http://assets.shopjimmy.com/media/ca.../a1552100a.jpg

Hi-Res Bottom Image Here:
http://i1208.photobucket.com/albums/...ps67d2fe37.jpg

Sorry what do you mean 'manage attachment'? I'm new here.

[tom66]

Re: Sony KDL-46Z4500 Completly Dead

Is there a smaller 450V capacitor, for example 10~47uF?

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

This is also what I've looked at so far:
http://i1208.photobucket.com/albums/...psabf24181.jpg

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

Is there a smaller 450V capacitor, for example 10~47uF?

Have you seen the images of the top and bottom of the board I uploaded? The only other caps I see are the ones in the top right which from top to bottom are 16v 2200uF (x3) 25v 3300uF (x1) 25v 1000uF (x1)

Edit: Unless you mean the really small ones next to the main 450v Caps which from moving away from the cap are 35v 100uF, 50v 4u7, 50v 10uF, then the other one close to that Sony chip is 25v 47uF

[tom66]

Re: Sony KDL-46Z4500 Completly Dead

What resistance do you measure across the terminals of the relay? It looks like it bypasses an NTC resistor.

[max1636]

Re: Sony KDL-46Z4500 Completly Dead

What resistance do you measure across the terminals of the relay? It looks like it bypasses an NTC resistor.

On the side with the leg that sits slightly back I get about 5 M Ohms, it takes some time to settle to that though. On the other side I get0 .493 k Ohms.