LG 50PS3000 Blue Light No Display

[Easky15]

Hi, I have a 50 inch LG plasma tv here, it seems to power up fine but getting no display, I tried disconnecting the z sustain first and got same symptoms, then tried removing power for y sustain and again same problem, also same when both removed, I tried testing va and vs voltages but both at 0, There is a blue light on the front of the tv to show its powered on but it changes to red/standby about 30 seconds after, I get voltage at both sides of all the 3 main fuses on the power board and can hear a slight buzzing from the set so it appears to power on just nothing happens on the screen at all, Any help would be great as im stuck with a 32 inch till i fix it, this ones my own tv that broke and im startin to miss it. :-o

I can upload pictures if needed,

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Have you checked the Vs on signal ?

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Check out my video this could be of some help:
https://m.youtube.com/watch?v=66SeSEFVc-8

[Easky15]

Re: LG 50PS3000 Blue Light No Display

Thanks ReeceyBurger123, I tested vs on and its 3.27v so dont think its same main board problem you had but good video, ya obviously know your stuff.. ;-)

[Easky15]

Re: LG 50PS3000 Blue Light No Display

0.6v at vs though, i think fault is in the power board

[tom66]

Re: LG 50PS3000 Blue Light No Display

Do relays click?
Isolate both Z- and Y- in case both have shorts.
Is control board LED flashing?

[Easky15]

Re: LG 50PS3000 Blue Light No Display

Do relays click?
Isolate both Z- and Y- in case both have shorts.
Is control board LED flashing?

Yes Tom, the relays do click on and with both Z - and Y - sus boards power removed the control boards led only blinks once the same time the relays are clicking on but after that nothing, same with all boards connected,

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Cheers, all fuses good did you say ?

[Easky15]

Re: LG 50PS3000 Blue Light No Display

Getting voltage at both sides of all 3 of the big main fuses but ill remove them from circut and check with multimetre to be sure when i get home in about 30 mins

[Easky15]

Re: LG 50PS3000 Blue Light No Display

Ok so I was wrong, 2 fuses on power board are ok but the 250v 4a fuse F801 is blown, Im not an expert on these now so not entirely sure what to test next,

[tom66]

Re: LG 50PS3000 Blue Light No Display

You can put a light bulb in place of the fuse as a test. 100W or so... If the bulb lights continuously then there is likely a fault

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Thats the Vs line fuse, more than likely the transistors that run the Vs line are shorted and have blown the fuse. Do you know how to check for S/C ?

[Easky15]

Re: LG 50PS3000 Blue Light No Display

Thats the Vs line fuse, more than likely the transistors that run the Vs line are shorted and have blown the fuse. Do you know how to check for S/C ?

Not sure how to check for short circuts mate, but i have an Atlas DCA so should make life easier, Ive all the gear but no idea..lol

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Ok im guessing that when you short the meter probes together when its on diode mode it beeps ?

[Easky15]

Re: LG 50PS3000 Blue Light No Display

You can put a light bulb in place of the fuse as a test. 100W or so... If the bulb lights continuously then there is likely a fault

Tried a bulb there tom but it didnt light up so i put another 4a fuse in, It blew straight away and also caused the main fuse to blow, :-o

Replaced main fuse and still get exact same symptoms so dont think i did any further damage apart from the fuse,

[Easky15]

Re: LG 50PS3000 Blue Light No Display

Ok im guessing that when you short the meter probes together when its on diode mode it beeps ?

Yes mate it does indeed, I have a fluke 87

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Ok its a similar principle for S/C if a device is blown ie a transistors all of its legs when probed will cause the meter to beep.

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Do you know what the transistors look like ? I have uploaded a picture the two devices mounted on a heatsink are the Vs and Va fets they are connected after the fuse, if those transistors are shorted they will blow that fuse.

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Remove the Psu and check the legs on them transistors, if you get a beep when testing any of the legs the transistor will be failed and will need to be changed. To test the transistor place one probe on a leg of the device then another probe on another leg do this and check all 3 legs of the device.

[ReeceyBurger123]

Re: LG 50PS3000 Blue Light No Display

Let us know what you get and will continue from there.