lg 60pb660v plasma tv

[thuss]

Re: lg 60pb660v plasma tv

when I disconnect the tcon from the main board and reconnect all the connections the main board does not turn the psu permanently on. I think its the main board as there is no red optical(?) light on the main board.

But as you said there maybe two faults.

I dont think its the buffers/y sus or x sus as there are voltages on the test points.

[Hamie]

Re: lg 60pb660v plasma tv

I still think you have a problem with y-sus and buffers.
Can you take a photo of them.

[Hamie]

Re: lg 60pb660v plasma tv

Found a pic.

On this connected please post what the vsc voltage is when the screen flashes and also when it's off.

[thuss]

Re: lg 60pb660v plasma tv

the vsc voltage (on both pins) when screen is on for 2 seconds is 53v.

then the screen goes blank the voltage continues up to and stays at 251v.(Should vsc be between 187 and 135? on the white sticker it states -187/NA/NA/135)

the above values are when main board is not connected to the psu. But even when main board is connected the above values are the same and just keep rebooting as the tv clicks on and off.

[Hamie]

Re: lg 60pb660v plasma tv

No it should be around 150v.

OK can you post the voltage with the buffers disconnected.

Also can you upload a picture of the top buffer.

[thuss]

Re: lg 60pb660v plasma tv

Yes will do- but do you mind if I ask why you want a picture of the top buffer is it for test points? I didnt see any burnt chips and I tried to do the test with the multimeter as per the 50pg3oo buffers but they seem fine.

Without the buffers connected there is no voltage on pins 3 and 4 vsc but on the connector block below the vsc is still 259v

[maxvalutech]

Re: lg 60pb660v plasma tv

I tend towards Hamie judgement re y-sus followed by control board second choice. Of course the first thing is to get the set to stay on which is why suggested check with control board off from main. The control can't get voltage from power board as far as I can see from pics. Isolation testing does point to a main board problem and delay in switch off maybe a component warmup time while the continuous start up loop means that part of circuit is ok?? The reservation I have is if the x and y plus buffers any not connected does that initiate a shut down!

[thuss]

Re: lg 60pb660v plasma tv

I tend towards Hamie judgement re y-sus followed by control board second choice. Of course the first thing is to get the set to stay on which is why suggested check with control board off from main. The control can't get voltage from power board as far as I can see from pics. Isolation testing does point to a main board problem and delay in switch off maybe a component warmup time while the continuous start up loop means that part of circuit is ok?? The reservation I have is if the x and y plus buffers any not connected does that initiate a shut down!

Thanks for the help- I'm also leaning towards a y sus fault. Your right the control board once disconnected from main can only get power from Y sus.

The reservation I have is if the x and y plus buffers any not connected does that initiate a shut down!
- I'm not sure.

On the 50pqs and 50pgs one buffer can be disconnected and it will show you half a screen and wont switch off.

[maxvalutech]

Re: lg 60pb660v plasma tv

Reading back to voltages you took I now note Vs 236v which if right is way too high and should be within 0.5v of recommended setting - overvoltage shutdown is likely at this level.

[thuss]

Re: lg 60pb660v plasma tv

I found a couple of shorted "mosfets" on the ysus -Can anyone advises me on what their equivalents could be

AUK C3C16 SMK0825- Ive been to rs and several other electrical retailers without success.

[thuss]

Re: lg 60pb660v plasma tv

I replaced the AUK C3C16 SMK0825 with 51n25.

The tv came on. However the vy voltage is still 181 even after I have turned it down with the adjuster. Allthe other voltages are ok.

So I assume I need to swap out another component on the Y sus board in order to get the vy down to around 150,

There are some pixels that slowly disappear ( i have reseated the ribbons between main board and tcon) also starnge is that it retains the tv menu on the left hand side of the screen - I suppose I should run the auto exgen gen?

[sordids999]

Re: lg 60pb660v plasma tv

Got one of these tvs found to be a faulty ysus but upon testing the psu I jumped 5.2v to Rlon but VS is measuring 316v and VA is measuring 68 volts Any ideas?
Thanks

[Andrew F. Ali]

Re: lg 60pb660v plasma tv

It may read 316V, but is that with a load or with no load? Use 2-120Vac 100W household incandescent bulbs in series as a load and then re-measure.

[sordids999]

Re: lg 60pb660v plasma tv

That's with everything disconnected just psu jumped
I'll try the bulbs as well

Thanks

[Andrew F. Ali]

Re: lg 60pb660v plasma tv

Yes. With everything disconnected from the PSU and using the Test bulb connected in place of the Y-SUS Bd. Your PSU is working properly, BTW. What fault are you getting??

[sordids999]

Re: lg 60pb660v plasma tv

Originally the fault was clicking from the psu found 3 shorted igbt on the ysus board and top buffer was shorted
So further testing wanted to see if psu was ok so was confused why the voltage was so high on the VS and VA

[Andrew F. Ali]

Re: lg 60pb660v plasma tv

Are you going to repair the Y-SUS Bd or are you looking for a replacement? Your PSU is good.

[sordids999]

Re: lg 60pb660v plasma tv

Well replacement ysus difficult to find unless you want to pay silly money so I'll look at repairing this ysus

[Andrew F. Ali]

Re: lg 60pb660v plasma tv

Nice. Let's di this then.

[thuss]

Re: lg 60pb660v plasma tv

Soz about late reply- it was a couple of large resistors next to the mosfets (theres two of them) that were shorted