LG 50PX4D-EB power problem

[Moggy]

I have a problem with this TV. When I plug in the mains, red light comes on, turns to orange, relay clicks TV back to red, and does nothing.

If I remove the lead to the YSUS board, marked +VA, GND, +VS. Red light, then green light comes on. No picture, but responds to remote ect.

Any advice please, thankyou. Stuart

[Moggy]

Re: LG 50PX4D-EB power problem

Sorry forgot to add pictures

[Caleb]

Re: LG 50PX4D-EB power problem

Training manual can be found here, You have to wait a minute for the "Get Manual" link to show up below the picture. but it sounds as if you have something shorted on the ysus or buffers and the protect circuit is shutting off the tv so it isnt damaged further

[Alastair E]

Re: LG 50PX4D-EB power problem

Could be one of the Pass Fets but most likely one of the IPM's--prob the SUS IPM is s/c.....

[Moggy]

Re: LG 50PX4D-EB power problem

Could be one of the Pass Fets but most likely one of the IPM's--prob the SUS IPM is s/c.....

Hya, thanks Eugene, much as I thought, I have downloaded the manual and will read through that. Thanks for the info.

Alastair I have had one with a similar problem, another TV, removed the IPM, it measured 0 Ohm so replaced it with one from China, lasted about two weeks or less and pop again.

What should the modules read across their pins? Assuming its removed from the board.

[ERICSSON89]

Re: LG 50PX4D-EB power problem

SUS IPM where is the voltage located, and what is it function? new to the forum

[Alastair E]

Re: LG 50PX4D-EB power problem

Using the boards notifications, there shouldn't be any shorts between those marked, GND, SUS_Up, SUS_Dn, ERC_Up/ERC_Dn or Vs....

New IPM possibly failed due to those cruddy caps around the DC/DC converter stage drying up, or maybe because it was an old/recycled one anyway. The Chinese sellers are quite good at making them Look new.....

L.G. IPM's are not available new, they never were-- any that are sold these days are used ones....

[Moggy]

Re: LG 50PX4D-EB power problem

OK, I will remove the board and check for shorts, if the IPM is at fault, best route for replacing \ repair please.

[Moggy]

Re: LG 50PX4D-EB power problem

Just a update. No shorts detected between gnd and VA+, +vs. Fuses are fine, inc pcb mount, advise please. Thanks Stuart

[Moggy]

Re: LG 50PX4D-EB power problem

I have checked shorts on, GND, SUS_Up, SUS_Dn, ERC_Up/ERC_Dn or Vs, all OK there. Is it posible to be power supply rather than YSUS board?

[Caleb]

Re: LG 50PX4D-EB power problem

The Ipm can fail open circuit as well, you can test the power supply voltages with the ysus harness unplugged. To load test it you can use a pair of 100 watt light bulbs wired in series across vs and ground. But the most likely failure is the ysus and buffers. Maybe Tom will be along soon to offer up some set specific advice.

[Moggy]

Re: LG 50PX4D-EB power problem

Ok thanks, will try load test shortly.

[Moggy]

Re: LG 50PX4D-EB power problem

Hya, thanks for the help so far, tried load testing the psu with light bulb, runs nice and bright no trouble. Have tried disconnecting buffer boards, both from YSUS board, still the same. Please can I have some pointers of what to check on YSUS board. Thankyou.

[tw2005]

Re: LG 50PX4D-EB power problem

Don't forget there's 4 IPMs and from what I've read(Coppell TV blog) I think it's good practice to replace the lot. I think they mention it's not unusual to repair the Ysus and then have the Zsus fail shortly after.

Also I've read the module rev needs to match the partner IPM on the same board. I think there's A,B & C

The Zsus is powered from the Ysus, so removing power from the ysus also isolates the Z, could be either board causing trouble.

[Moggy]

Re: LG 50PX4D-EB power problem

I have tried removing power from the ZSUS board to, as I did notice power comes from the YSUS board.

[Moggy]

Re: LG 50PX4D-EB power problem

It seems I have been barking up the wrong tree, it is the ZSUS board shorted. VS and ground read short. I can remove the IPMs, then check for shorts.

Need advise, there is another board on Ebay for £30-00. Remove the IPMs to confirm its one or more shorting, replace the faulty one, or replace all four on Z and Y SUS boards.