Vizio jv50p HDTV10A no power no relay click

[ajt9170]

Hi All, I repaired this plasma about 4 years ago for the power supply caps issue by replacing the power supply with one from a older P50HDM part number USP700M-50LP, I had in my parts graveyard.
This unit works anywhere from 12 to 20 hours daily without any issues.
A few days ago I fell asleep with the tv on. When I awoke the tv had no sound, on screen volume indicator worked, images and osd worked fine, I also changed the source to TV ant but got no channels or image, tried other inputs and worked fine but still no sound.
I decided to restart the unit but after switched off it would not power up again. I unplugged it and waited about an hour, but it made no difference, the vizio logo wound stay orange ant not change to white, also when plugged in the relays would not click at all.
SO I figured power supply again and rebuilt the old one, pop open the back panel expecting to see some bad caps but everything seemed fine.
Installed the rebuilt power supply anyway but nothing happened, same issue, no relay click.
Checked voltages on ASD= 4.5 , 5vsb= 5v, all else is 0.
So I figured that the problem must be the main board since the tv worked fine untill I turned it off Plus not having tv tuner operation.
I found another fellow on this forum with a similar situation but that unit at least had the relays activating. His problem was solved by replacing a LDO, the one he replaced is actually OK on mine.
PlainBill uploaded a picture indicating all the LDO on that board, unfortunately I have no reference voltages for them. Some measure 3.5 others 2.6 and still others nothing at all.
Any help will be greatly appreciated.

[ajt9170]

Re: Vizio jv50p HDTV10A no power no relay click

Guess ill keep talking to myself, found one regulator on main board that was bad, replaced it and all is back to normal.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

hello i know it has been a couple of years but i was wondering if you remembered which voltage reulator it was you replaced. i have a jv50phdtv10a tv that i am working on. the set powers up (logo turns white) however i have no sound or picture, but i do have the u33 regulator that feeds u7 and u9 putting out a stead 3.28 volts. i am at a loss.

[budm]

Re: Vizio jv50p HDTV10A no power no relay click

So what are the DCV reading on all 3 pins of those regulator ICs? That will be a start.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

hello sorry for the slow response it has been a busy couple of days. the voltages on the 3 pins are as follows.
u33- in 4.8v
out 3.28v
adjust 1.2v

i managed to find a service manual for that particular main board and the u33 as well as the u7 and u9 voltages are all correct. however at the j10 connector, pins 10, 11, and 12, all labeled 5vsc should put out around 5v. when i powered the unit on, there are no relay clicks, no image and no sound but the vizio logo does turn from orange to white. the voltage readings on that j10 connector at the corresponding pins is only reading .80 volts. but i am thinking that because there are no relay clicks the power board is not being turned on as i am not getting 12v readings off the pins.

[budm]

Re: Vizio jv50p HDTV10A no power no relay click

Vout of the Adjustable 1117 series is = 1.25Vref +Vadj, so the Vout of that U33 should be = 1.25V +1.2V = 2.45V (basically 2.5V).

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

yes you are absolutly right, that was my mistake i had the voltages mixed up with another regulator. the adjustment pin on u33 is reading 2.2. so the 1.25 ref and the 2.2 adjust would come to 3.3 volts which is what the service manual is saying should be the output on u33.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

well the problem was staring me in the face the entire time hidden under a piece of tape. during my search to check the regulators on the main board i could not find u10. searched and searched and searched but couldnt find it. then i happened to take a quick look at the board while taking a break from another project and found the missing regulator under a piece of tape, and sure enough theres a voltage issue because the out pin got so hot it broke off, on all 3 boards. (yes i have 3 main boards its a long story) anyhow off to find a new regulator to replace u10 and check its input voltage since i have a feeling its way too high.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

well the problem was staring me in the face the entire time hidden under a piece of tape. during my search to check the regulators on the main board i could not find u10. searched and searched and searched but couldnt find it. then i happened to take a quick look at the board while taking a break from another project and found the missing regulator under a piece of tape, and sure enough theres a voltage issue because the out pin got so hot it broke off, on all 3 boards. (yes i have 3 main boards its a long story) anyhow off to find a new regulator to replace u10 and check its input voltage since i have a feeling its way too high.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

oh, cancel that apparently the middle pin, even though theres a spot to solder a pin that is labled vO doesnt have to be soldered. the tab is the output and the output is 2.6, which is right where it should be.

[budm]

Re: Vizio jv50p HDTV10A no power no relay click

oh, cancel that apparently the middle pin, even though theres a spot to solder a pin that is labled vO doesnt have to be soldered. the tab is the output and the output is 2.6, which is right where it should be.

It is the same setup as the 1117, the middle pin in connected internally to the big tab.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

I discovered that the hard way lol. I did manage to get the rest of the regulators readings they are as follows.

U. Vin. Vout. Adj.
33. 4.3. 3.36. 2.07
8. 4.82. 3.28. 2.04
4. 4.3. 3.26. 2.02
3. 0. 0. 0. ????????
7. 3.37. 1.26. .02
9. 3.37. 1.49. 0?????
35. 4.3. 3.2. 1.99
10. 4.29. 2.61. 1.36
2. 4.3. 3.23. 2


Any thoughts on why u3 has no in or out voltage??

[budm]

Re: Vizio jv50p HDTV10A no power no relay click

Is U3 also 1117? It can be that the rest of the switched power supplies are not on at this point.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

No u 3 is not a 1117. It's larger, I'm unable to get the exact number off it at the moment. I'm also wondering if it's part of the circuit that is responsible for turning on the psu. I'm trying to find out what pin on the j10 connector turns it on so I can short it with the standby voltage and see if the relays click.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

Here it is.

[budm]

Re: Vizio jv50p HDTV10A no power no relay click

Look to be LM7805 or something like that.
As you can see, there are 3 SMD fuse by the connector that goes to the power supply board and one of them should have 5VDC at both ends which will be the standby power supply, the other two fuse are fed by switched power supplies which probably are not on right now but you can check all those 3 fuses just to make sure they are OK first.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

I've actually checked those fuses lol. The 5v fuse is on and reading 5 volts at both ends. The other two fuses both have continuity. Oddly the voltage reading on them was around .8 which was the same voltage I was getting at the 5vsc pins going from the psu to the main.

[budm]

Re: Vizio jv50p HDTV10A no power no relay click

Right now the main board is not sending the PS-ON to turn on the rest of the power supplies so there will be no Voltages on the other two fuses, only the 5VSTBY is working, so more in-dept troubleshooting of the main board is required. May be something is locking out the main board from sending the signal.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

It was working after I replaced u33, then after about 6 hours picture and sound went out. Vizio logo still turns white but no relay clicks and no picture or sound.

[shawt99]

Re: Vizio jv50p HDTV10A no power no relay click

new update, replaced the main board, tv turned on and ran great for about 5 minutes then a fuzzy sound and nothing, no sound no picture. something keeps burning up the main board