Toshiba 46xv645u dead power supply

[nicholas1110]

Hello,

Having a bit if a hard time with this toshiba. I have repaired this tv 3 times for the same issue. The symptoms of the tv are dead, no standby voltage. So let's start at the beginning of the story. First repair attempt, I replaced the open cement fuseable resistor r850, and q880 which is str-y6456 ( was not shorted). Sent the tv back to the customer, tv ran for about a 2 weeks. Tv came back. Same r850 fuseable resistor was open. This time I ordered a repair kit, which came with r850, bridge rectifier d820, and 2 47ohm resistors at r827, r828 ( which are running hot as the board has browned near them but they show 47ohm still. Tv ran for about 5 days this time, and back with the same r850 resistor open. There are no shorted mosfets. My only thought is maybe the 2 150uf 450v caps.

So main question, what can cause this fuseable 1.8ohm resistor to keep opening?

I have 3 more of these TVs in my shop right now with the same issue, and I'm hesitant to send them home. I've let them run here for over 48 hours now strait with no issue.

Any help would be appreciated.

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

Forgot to add power supply part number is v28a000962a1 pe0702A

[budm]

Re: Toshiba 46xv645u dead power supply

Please upload the pictures of the whole backside of the TV, and also the bottom side of the power supply board.

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

For some reason my phone will only let me do one photo at a time

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

Another

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

I don't have one with the back off the tv right now, I took these before I repaired the board and put the tv back together.
I've searched around the forum and found a couple threads about this board but no definitive answers.

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

Ok, found the issue. Relay sr80 has dirty contacts in it causing the r850 to open. I have opened the relays in the TVs I had running, cleaned them up and should be good to go. Hopefully this info helps the next person with this issue.

[ReeceyBurger123]

Re: Toshiba 46xv645u dead power supply

Ok, found the issue. Relay sr80 has dirty contacts in it causing the r850 to open. I have opened the relays in the TVs I had running, cleaned them up and should be good to go. Hopefully this info helps the next person with this issue.

Interesting fix thanks for posting

[Michale32086]

Re: Toshiba 46xv645u dead power supply

I just got one of these in.

OP, did you get 3 blinks on the Power LED when plugged in???

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

Hi,

These model, the green light will blink 3 times then repeat approx 2 times when tv tv is first plugged into power, or not be powered on for a certain amount of time.
Did yours have the bad fuseable resistor? If so make sure you replace the sr80 relay or it will fail again. You can also open the relay and clean the arc marks off the contacts.

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

Mine came to me as dead, no signs of life when first plugged into power. Opened up to find the fuseable resistor open.

[Michale32086]

Re: Toshiba 46xv645u dead power supply

Hi,

These model, the green light will blink 3 times then repeat approx 2 times when tv tv is first plugged into power, or not be powered on for a certain amount of time.
Did yours have the bad fuseable resistor? If so make sure you replace the sr80 relay or it will fail again. You can also open the relay and clean the arc marks off the contacts.

The SR80 relay closes upon plug-in. Then, after unplugging, it opens, closes and opens again..

The SR81 relay just sits there...

Which part number is the fuseable resistor??

Are they they ones marked??

Thanx for the reply...

[nicholas1110]

Re: Toshiba 46xv645u dead power supply

The resistor is r850, it is next to the relay. Since you have signs of life it is most likely good. It should read 1.8ohm or so. When it's open it's much higher, but if your relay is functioning then the resistor is most likely good as it feeds power to the relay. There is a fuse in the upper right corner of the board, check that fuse. The other issue I've had with this board is the q880 regulator. Which sometimes will open that fuse when it fails. Or sometimes just contestant 3 blink code like the older toshiba power supplies

[Michale32086]

Re: Toshiba 46xv645u dead power supply

OK, this is really weird...

First off, R850 does show 1.8ohm (1.9, but close enough). So I am guessing we're good there...

Here's the weird part..

I let the Power LED blink for a while. 3-blinks 3-blinks 3-blinks for at least 7-9 repetitions..

Then I pushed the power button..

Power LED blinked once. Then blinked twice.. Then went back to the 3-blink mode..

Since this is obviously not related to your issue, I don't want to hijack your thread..

I am going to start my own thread on this, but would appreciate any insight you may have, since you have worked on more than a few of these.

[BackYardBert]

Re: Toshiba 46xv645u dead power supply

I have the same dead TV issue with the same power supply board (V28A000962A1) in a Toshiba 52XV645U. Bridge Rectifier @ D820 bad. Ceramic resistor fuse @ R850 bad. 47Ohm resistors @ R827 & R828 Ohm out fine but have blackened the PCB. I want to replace or clean the 5V Relay @ SR80 as you suggest. I can't find a replacement. How do you clean the switch contacts? I assume you desolder and remove the relay from the board to remove the cover. Then how did you clean the contacts? A spray? A file? Thanks if you get this!

[MvZiC MaN]

Re: Toshiba 46xv645u dead power supply

I have the same dead TV issue with the same power supply board (V28A000962A1) in a Toshiba 52XV645U. Bridge Rectifier @ D820 bad. Ceramic resistor fuse @ R850 bad. 47Ohm resistors @ R827 & R828 Ohm out fine but have blackened the PCB. I want to replace or clean the 5V Relay @ SR80 as you suggest. I can't find a replacement. How do you clean the switch contacts? I assume you desolder and remove the relay from the board to remove the cover. Then how did you clean the contacts? A spray? A file? Thanks if you get this!

I have the same Board from a Toshiba 47ZV650U. Same problem,
No power at all.
Tested R850 and it is Open. Bridged the contacts to test and it powerd on just fine. But i also noticed the Resistors on mine @ R827 and R828 are Blackened around them. Did you ever Find out the cause or Fix the issue? Thanks!

[dskall]

Re: Toshiba 46xv645u dead power supply

Read post #7

[MvZiC MaN]

Re: Toshiba 46xv645u dead power supply

The contacts on SR80 dont look dirty too me. Will upload a pic if i can yet.

Edit: Heres the best photos i could get.





Can try to get better ones 2mrrw.

[budm]

Re: Toshiba 46xv645u dead power supply

The relay contact are blackened and pitted.

[MvZiC MaN]

Re: Toshiba 46xv645u dead power supply

Does that mean i need to replace the Relay as well? or is there a certain method to Cleaning/restoring the contacts of the relay?