Zenith/LG z50px2d new PSU swap-in...

[SlickClick]

Picked up this 50inch user said the tv started out fine for years then one day they had to press the power button twice, then had to hold it for a few seconds, eventually they said it took an hour holding the power button on for it to come on....

Took it home popped it open there was about 13 blown caps on the high power side between the transistor sinks... I found a guy locally who had a "brand new" PSU... I inspected the board doesnt look like a screw ever touched the board not a hot spot on it looks good...

Now when I power on the unit I get 3 green blinks and then back to red standby...
I cant get the PSU to stay on long enough to test voltages out...

I suspect that because the PSU is supposedly Brand New that maybe i have to set the Vs voltages higher; but how do i get the board to stay on to set these values..?

Any switching bypass or pin tricks to get the PSU to stay on so i can check and set Vs values..?

[SlickClick]

Re: Zenith/LG z50px2d new PSU swap-in...

Been looking all day... Downloaded the service manual from toms archive...

The image for 4.2 is so blurry I cant tell what it says to do...

How do I get this PSU to turn on without the mainboard connected..?

F-It imma just start touching shit together and see what happens...

[tom66]

Re: Zenith/LG z50px2d new PSU swap-in...

That's one surefire way to fry shit.
I had a 50" LG PSU which wouldn't fire up until I tweaked the Vs pot slightly up.

[SlickClick]

Re: Zenith/LG z50px2d new PSU swap-in...

I found that if i bridge the the blue wire to the main board with the first white wire next to it the PSU stays on... However I am getting no voltages out of it... so i am guessing there is a second stage that i cant figure out how to get on or the board is just bad...

[tom66]

Re: Zenith/LG z50px2d new PSU swap-in...

Both PS-ON and VS-ON need to be turned on. Make sure the panel or sustains aren't connected.

[SlickClick]

Re: Zenith/LG z50px2d new PSU swap-in...

Yea i disconnected everything from the PSU but the mainboard at first and get 4 green blinks i believe....

even hooked up that way when it clicks briefly i only get less than 2v on Vs...

P801: When I jumper ac-on to rl-on the PSU high side clicks on...
i tried touching ac-on to vs-on but does nothing... what voltage is required to turn vs-on to on state..? 5v 12v..?

[tom66]

Re: Zenith/LG z50px2d new PSU swap-in...

AC-ON is an OUTPUT from the power supply, not an input. Use 5V Standby as your source. Need to turn on RL ON, M5V ON, 3V3 ON, and VS ON.

[SlickClick]

Re: Zenith/LG z50px2d new PSU swap-in...

I am getting all good low voltages but no Vs or Va voltages... Vcc is at 4.4v

there is no 3.3v there is POD... I tried to take a picture with this gopro camera I bought to put down my septic pipe but it sucks so bad i cant even get a good shot... -ie dont buy one unless your skydive or want a cheap camera snake lol-

just did some more tinkering and found that if i hook up the low voltage connections i get fans and such on but when i hook it to the main board 3 green blinks but if i hook it to the main board with the bypass wires all in it does a start up like normal with the green light but still no high voltages at all at any point...

is there something that turns on the high voltage that i am missing..?

[tom66]

Re: Zenith/LG z50px2d new PSU swap-in...

VS ON turns on the Vs & Va...

[SlickClick]

Re: Zenith/LG z50px2d new PSU swap-in...

after doing a bypass type startup a couple times i removed all the jumpers and TV is starting up fine now...

it didnt wake up the PSU fully i guess until i had it hooked and bypassed on the mainboard... geting 59 and change on one and 198 on the other...

too bad the electronics store wants $2.50usd/ea a cap; i could have likely fixed the original but for $30 for a new PSU just made sense... the whole tricking it into thinking its ok was another story... cause i consistantly got red - 3 green blinks - red for 2 days straight...

[tom66]

Re: Zenith/LG z50px2d new PSU swap-in...

Don't use caps from some electronics store unless they are high quality, the average shop does not supply good caps (Panasonic FC/FR/FM, Rubycon YXF/ZLH, Nichicon PW/HE, etc.) DigiKey or Badcaps.net has good quality caps available at reasonable prices.

[SlickClick]

Re: Zenith/LG z50px2d new PSU swap-in...

he had sanyo caps... but at $2.50 a pop im good... I needed like over a dozen caps too... so its not worth fixing the original PSU...