Lg50pc1da

[Cornboats]

I have an LG 50 plasma that has no picture as such. The sceen is black but has flashing white light. Sounds rather like a fluorecscent tube when the starter does't work, Noise is coming from the left side of the Ysus board-top buffer.
I 've checked voltages around the boards and pinouts correspond with written values.
I've swapped the y-sus and z sus boards with ones that I thought were ok & sympton remains the same.

In desperation I moved the ysus,z sus and control boards to another PDP50x3I have and the syptom is exactly the same.

What to check next?

[Remeniz]

Re: Lg50pc1da

I have an LG 50 plasma that has no picture as such. The sceen is black but has flashing white light. Sounds rather like a fluorecscent tube when the starter does't work, Noise is coming from the left side of the Ysus board-top buffer.
I 've checked voltages around the boards and pinouts correspond with written values.
I've swapped the y-sus and z sus boards with ones that I thought were ok & sympton remains the same.

In desperation I moved the ysus,z sus and control boards to another PDP50x3I have and the syptom is exactly the same.

What to check next?

Logic proves the control board is the odd one out here. So this is what i'd suspect as faulty.

[Cornboats]

Re: Lg50pc1da

I thought that too so I then swapped the control board. No change.

The only item I haven't swapped is the tuner- NO couldn't be could it?

[PlainBill]

Re: Lg50pc1da

I thought that too so I then swapped the control board. No change.

The only item I haven't swapped is the tuner- NO couldn't be could it?

You didn't swap the X drivers and the plasma panel itself. Or perhaps we aren't referring to the same things. I'm not familiar with that TV, but some sets have the tuner / signal input board separate from the 'TV control' board - the one that does the actual signal selection and processing. That board sends a signal to the Main logic control board through the LVDS cable. The main logic control board sends the signal to the Sustain boards. Given the symptoms, I would be confident the problem is somewhere past the LVDS cable. The buffers were a logical choice, but since you have two sets using the same plasma panel it's time to do parts swapping. The worst you could find is the problem is the panel itself, and you have a tested set of good boards to sell.

PlainBill

[Cornboats]

Re: Lg50pc1da

Bill. Sorry I've not replied sooner. Your right I didn't swap buffers. Those and the tuner , which is seperate are the only boards I haven't swapped. I put the job to one side but will put back on the bench and have another go.

Thanks for taking the trouble to respond.

[rayrod81]

Re: Lg50pc1da

What it sounds like to me is that the Y-Sustain is bad and took out one of the buffers. I have fixed quite a few of the 50X3 panels that had the same problem. If you disconnect the buffers one at a time and power it on you will find out which one is bad. Make sure you use a good Y-Sustain or it might take out the other buffer. The good thing is that the buffers can be repaired cheaply by replacing the 3 FETs on each board. I have not yet seen an IC go bad on these boards but it is possible. The Y-Sustain is another story because if that is bad then you can either buy the two IPMs and replace them, which is a pain, or send it in to get fixed. Either way it will cost you close to $100 but a new board will cost close to $150 or more.

[Cornboats]

Re: Lg50pc1da

Many thanks for your info. I'll check it out and let you know.-May be some time!

[snipersquad100]

Re: Lg50pc1da

Did you fix it in the end???

[Cornboats]

Re: Lg50pc1da

Changed the ysus board and all is well.

[mmartell]

Re: Lg50pc1da

A failed open ipm (can't remember erc or sus ?) On the ysus will give these symptoms.

[Cornboats]

Re: Lg50pc1da

I think on one of the ipm's were shorted.

Do you know anything about the psu in this model? Just posted problem I'm having trouble with.