50" LG Y-sustain IPM modules

[dkneyle]

Re: 50" LG Y-sustain IPM modules

I have an LG 50PX5D with the symptoms that very much meet those of this thread. That is: Switch power on, power supply tries to start, fans come on, after about 5 seconds drops back into standby. Disconnected supply to Y-Sus board and the power supply stays up. Reconnected the Y-Sus supply and disconnected the supply to the Z-Sus board - power supply drops back into standby. Therefore, along the lines of this thread I assume probably the IPM chip/s have failed on the Y-Sus board. However the fuses are in-tact. No signs of any visible damage such as bulging caps. (I have also replaced the power supply so I'm confident it is OK.) Because I don't have the gear I wasn't about to changeover the IPM modules, but planned on buying a secondhand Y-Sus board. However before investing >$120 I wanted to check what others thought from my described symptoms and self diagnosis.

[dcapper]

Re: 50" LG Y-sustain IPM modules

I was going to replace mine but the work involved was a pain. So I got lucky and bought a used ysus board on Ebay for $50 shipped.

[dkneyle]

Re: 50" LG Y-sustain IPM modules

I was going to replace mine but the work involved was a pain. So I got lucky and bought a used ysus board on Ebay for $50 shipped.

And I assume that got you going again??

[tw2005]

Re: 50" LG Y-sustain IPM modules

I have an LG 50PX5D with the symptoms that very much meet those of this thread. That is: Switch power on, power supply tries to start, fans come on, after about 5 seconds drops back into standby. Disconnected supply to Y-Sus board and the power supply stays up. Reconnected the Y-Sus supply and disconnected the supply to the Z-Sus board - power supply drops back into standby. Therefore, along the lines of this thread I assume probably the IPM chip/s have failed on the Y-Sus board. However the fuses are in-tact. No signs of any visible damage such as bulging caps. (I have also replaced the power supply so I'm confident it is OK.) Because I don't have the gear I wasn't about to changeover the IPM modules, but planned on buying a secondhand Y-Sus board. However before investing >$120 I wanted to check what others thought from my described symptoms and self diagnosis.

The ZSUS get power from the YSUS so a bit of an assumption it's good too.

Also I've seen a bad ysus cause R9,R91 10ohm 0.5W SMD resistors to burn up on the ZSUS. Bottom left near a bank of capacitors.

Last one of these i fixed I sold for about $180 18 months ago.

[dkneyle]

Re: 50" LG Y-sustain IPM modules

The ZSUS get power from the YSUS so a bit of an assumption it's good too.

Also I've seen a bad ysus cause R9,R91 10ohm 0.5W SMD resistors to burn up on the ZSUS. Bottom left near a bank of capacitors.

Last one of these i fixed I sold for about $180 18 months ago.

You are a wealth of knowledge. I looked at those resistors. No sign of stress. I put my meter across them: I get a reading of 40K, not 10 ohms as expected. From your experience, when they blow, do they usually look physically damaged?

I was assuming that the Y-Sus was the main culprit because if I removed Z-Sus from the power daisy chain the power supply still wouldn't hold up.

So, here's the question for you based upon your experience. If I changeout the Y-Sus board with a working board, and replace those resistors on the Z-Sus board, will that generally get things going? Or is the Z-Sus board also likely to need a complete changeout??

[tw2005]

Re: 50" LG Y-sustain IPM modules

You are a wealth of knowledge. I looked at those resistors. No sign of stress. I put my meter across them: I get a reading of 40K, not 10 ohms as expected. From your experience, when they blow, do they usually look physically damaged?

I was assuming that the Y-Sus was the main culprit because if I removed Z-Sus from the power daisy chain the power supply still wouldn't hold up.

So, here's the question for you based upon your experience. If I changeout the Y-Sus board with a working board, and replace those resistors on the Z-Sus board, will that generally get things going? Or is the Z-Sus board also likely to need a complete changeout??

I don't have that much knowledge on these but there would be a way of confirming the IPMs on the Z are bad or not using a meter but I don't know the procedure. Maybe try googling test lg ipm or copellTV might have a blog or info on it.

I'd expect burning or maybe a pinhole in the resistors but being such a low resistance it is conceiveable they are open or gone high.

On the one I had which was an aborted repair by someone else they burnt making us think the ZSUS was bad but with that one it turned out to be ok after replacing those and repairing the y.

I think they may be in parallel those resistors too but unsure so 5 ohms may be expected there.

One thing is for sure you should see at least theresistor value or lower there, definitely not higher.

too long ago for my memory now, that's all I got for you.

Someone else may have better info for you.

[tw2005]

Re: 50" LG Y-sustain IPM modules

not sure if this doc helps but paragrah 2. both modules would need testing.

see how you go. you'd have to go by the pin description, i think the photo is a different module but a picture is shown of the 50X3 and they're the same modules paired on both the y and z

[dkneyle]

Re: 50" LG Y-sustain IPM modules

So, I changed the Y-Sus board over. I also found that two 10 ohm resistors on the Z-Sus board had gone open circuit and they were replaced. (Tks tw2005 for that hint.) The plasma fired up all OK. After about 10 minutes I noticed a horizontal black line towards the bottom of the screen. I don't think it was there when I first got the TV going? I did take out the y-driver boards to check for shorts, so I'm hoping it's just a cable not pushed home, or some dust. I will report back! The IPMs seem to be running warm but not hot. The voltages are spot on - I didn't need to reset them. We've gone from a completely dead set to one that runs except for a minor screen blemish which I'm confident I'll get on top of.

[dkneyle]

Re: 50" LG Y-sustain IPM modules

(End of the story.) I removed the ribbon cable on the lower buffer board, gently brushed it and the connector with some metho spirits (alcohol), reassembled. ALL GOOD! Giving it a good heat soaking at the moment to see that all holds up well. Anyone who comes to this thread looking for guidance with a similar problem, just check those 10 ohm resistors on the Z-Sus baord. I would never have known about those except for the tip off. I replaced with conventional 10ohm 1/2 watt resistors; there's plenty of room to do so.