LG 60PV250 sound OK, no picture.

[maxvalutech]

This is a heavy monster given to me "sound OK no picture". Obvious someone has had a look at it as rubber pad missing from under ysus and a broken screw in back panel. Took voltages and VS 203v , VA 55v both OK per sticker and stay up as well. VZB 105v may be a little low? But both VY and VSC are all over the place - what I think is happening is the voltages are both being generated then quickly running down due short somewhere then regenerating etc etc. No difference with buffers disconnected nor with Z disconnected. Smaller 5v and 17v OK and set reacts to inputs. When on it stays on until turned off. LED is visibly working on logic board and looks to be . . - - repeating. Looks like Ysus problem to me. Can't see anything obvious but will go over board with hot iron - its EBR73561201. No sign of life on screen no blink at all. Did try pattern gen from logic but nothing of course. Pics a bit later but usual setup. Meanwhile, pointers welcome.

[tvtimmy]

Re: LG 60PV250 sound OK, no picture.

You have the cracked solder joints on the inductor coils problem. Start with the x main . Resolder them and then everything that is attached to a heatsink. You have to check the ibgts for shorts. You will find at least 4. Change them out. Then do the same to the y main. You may not find any shorts and be good to go.

[maxvalutech]

Re: LG 60PV250 sound OK, no picture.

Thanks tvtimmy and I had read of that in my research. Unusually perhaps both Y and Z mains in this set are very good for solder joints. I took your advice and reflowed all the heatsink items but no change. The Z board voltage is steady at 105v the Y continues mad fluctuations on Vsc and Vy from 0 to 230 or so and no negative readings in those. Research also showed a repair kit for Ysus being 8 MOSFETs/diodes, 12 smd resistors, and fuse F102. All fuses on my boards are OK and smds look alright. As the Vs and Va are good and stay up the problem should be in the Vy vicinity. I haven't found a circuit yet - some service manuals similar sets downloaded but nothing seen re Y board as yet. And must add the pads from under Z board also missing - wonder if they were ever there?

[goldbird78]

Re: LG 60PV250 sound OK, no picture.

are all ysus screws in tight ?

[maxvalutech]

Re: LG 60PV250 sound OK, no picture.

Yes and there is enough of them isn't there!

[mmartell]

Re: LG 60PV250 sound OK, no picture.

Now resolder the joints on any transformers on the ysus.

[goldbird78]

Re: LG 60PV250 sound OK, no picture.

I had a similar problem on a 60pv400 but the picture would go off after about 10 min (tv heating up) and what I found is there was a hairline crack on a solder joint on the Ysus board that only could be seen with a magnifying work bench light. I am trying to remember where it was and when I reflowed it the problem disappeared. Inspect the back of the board again very closely. It may have been one of the coils, again it was very hard to see with the naked eye.

[maxvalutech]

Re: LG 60PV250 sound OK, no picture.

Thanks guys will do that. Visitors today so won't get much done but will feedback as soon as.

[maxvalutech]

Went over the board again including coils and transformers plus a couple of other things. Am not the best soldering person in the world but no change with both Vsc and Vy voltages continuing to fluctuate. I will next try splitting buffers and try the set with one or the other disconnected just in case some screen reaction. Did try with both disconnected but no change then.

[maxvalutech]

Re: LG 60PV250 sound OK, no picture.

Never got much further with this set as I have it outside (covered) and winter set in. But now I have two of these almost the same as a friends went bad with picture coming and going until finally just black screen. On its ysus fuse 102 open and several components shorted on heat sinks. The Vs and Va came up good before protection kicked in. So even though different ebr number I put ysus from first set into this one to test that way. Again Vs and Va good and steady but also again with this particular board the Vsc and Vy voltages jumping around all the time still. Must be some component in the relative voltage generation circuit of the ysus playing up. I will try comparison testing of both board components but meanwhile any ideas??

[maxvalutech]

Re: LG 60PV250 sound OK, no picture.

Although obvious differences in the two ysus the only real disparity I have found in bottom circuits of these boards is with coil EBJ60730703 where on original set there is no continuity showing whereas on recent set there is. The coils have different sub numbers being DK101115T for older board and DK110919T on later one. Can't find any information on these. Have resoldered connections but no change. Is this a transformer for the voltages that are fluctuating??

[Nick's Tvs]

Re: LG 60PV250 sound OK, no picture.

If at any point you had the set turned on with even 1 screw missing or improperly seated on the Y or Z sustain board, then that board went bad. They are very sensitive to being grounded properly. I would not check your fuses for continuity but instead the transistors for shorts. Get both the Y and the Z out of circuit and check the transistors on the heatsink for shorts. If any of them have the middle pin shorted to one of the outer two pins, then you know those boards are going to need servicing. You may have two bad boards since someone else messed around with them, so I would check both.
These boards are very expensive to purchase as they commonly fail and are no longer available as new. Most people on eBay that have them for sale place a very hefty price tag on those parts. The good news is that since this is a common issue there are a lot of shops that now offer services for repair of these boards like my shop.
Just brows around and make sure to go with a company that offers a warranty on the repairs.
Good luck

[maxvalutech]

Re: LG 60PV250 sound OK, no picture.

Thanks Nick and apology for not replying earlier - been sidelined for weeks with a severe cold. If I were in the US would send board to you without hesitation due your great reputation. Not a service generally offered here in Oz though and as I would expect all up cost to be towards $200 then very difficult to recommend that for a 7/8 years old set of dubious history. Recently advertised here 65" Led set $695 new with warranty (basically 3 years with our consumer overriding warranty). Any search for board shows "out of stock" and repair kits ridiculous prices inc postage. Will check as you suggest as the two boards have different faults as far as I can see from tests.and may still be able to get one good one out of the two.

[matto_down_under]

Re: LG 60PV250 sound OK, no picture.

I had a similar problem on a 60pv400 but the picture would go off after about 10 min (tv heating up) and what I found is there was a hairline crack on a solder joint on the Ysus board that only could be seen with a magnifying work bench light. I am trying to remember where it was and when I reflowed it the problem disappeared. Inspect the back of the board again very closely. It may have been one of the coils, again it was very hard to see with the naked eye.

G'day fellas, I recently found a LG 60PV250-TB on the side of the road, had sat through a little bit of drizzle. Took it home and plugged it in, works and everything, but turns off after 5/10 mins, sound stays on. Occasionally there is a little bit of a sparkly thingy going on, very minor. When the image is on the lighter areas flicker, anything white is pretty noticeable. Would the above quoted cracked solder cause flickering?

I have checked Va and Vs voltages, adjusted Va a little, both seem to drop about 2-5 volts periodically. Any tips/clues would be greatly appreciated.

Cheers.