LG-50PQ6000 clicks and clicks and clicks

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

OK, that's annoying. Like the LG I fixed, it goes straight into the main microcontroller for the power supply...

Let's try another way of finding them. All but one or two of the optos will face the same way. The two facing the opposite way may be the ones of interest. Can you find these? There's a little dot on them to identify orientation.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

These any better?

I did a simular course about 20 years ago. Certainly worth your while mate.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Yep PC101 and PC102 have the black dot on the Primary coil side.

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

OK, this is one opto, there are many more, please see which way they are facing as I mentioned in the previous post.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Yeah you circled PC102 they have a little corner tab on the circuit drawing to indecate oreentation. PC101 is the middle one. PC101 and PC102 are the 2 out of the 6 that are the same way.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Yep PC101 and PC102 have the black dot on the Primary coil side.

Thought I might add and probably needless to sat TV's were tubes back then lol

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

OK can you post an overall shot with a clear shot of the traces leading to those optos...

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

So you short the O/P on the opto isolator?

Hard to get a good pic mate.

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

Wrong side. We need to verify if these are the right optos as I have no experience with this PSU, please post photo as I outlined above, thanks.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Wrong side. We need to verify if these are the right optos as I have no experience with this PSU, please post photo as I outlined above, thanks.

Sorry mate! Any better?

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

Sorry, meant wrong side to bridge... can you post a picture of the bottom of the PSU where the traces connect to those optos. On the live side of the PSU.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Shorting the input to the optoisolator?? That has got me confuddled never mind if it works it works.

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

I need to see a larger scale image as on mine, the traces went all the way across the PSU. The optocoupler's input is on the LIVE side and is usually driven by some TL431's, I am trying to locate these if so I know they are the right ones. Sometimes there is just one and the other serves an important function, other times there are two.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Ok cool will work on taking a picture tomorrow in the day light.

Thanks for your help with this mate. :0)

Jarrett

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

HI mate,

Just managed to get a couple of snaps outside before the sun went down:

One of the whole board and the other or the opto-isolator outputs. I dont know if you can see IC101 and IC102 but there both 431A's??

Jarrett

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

OK, they definitely look like the AC detect ones. I've highlighted where to make the bridges; keep them separate from each other.

I just hope this works - as I'm not 100% that this fault applies to this PSU. Otherwise, will have to check elsewhere.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Cool, I will look into it. So whats your theory behind this? Also have you ever done any measurements in this area with a scope or anything.

I gather the opto isolator isnt stable and causing that IC to throw a wobbler? and shorting it gives a high state on the and makes it work do you think??

J

[tom66]

Re: LG-50PQ6000 clicks and clicks and clicks

I did briefly scope it, and whenever my set tried to power up the AC-DET went low, and the microcontroller on the main board shut everything off, restarting the cycle. I sometimes saw a flicker from the panel but nothing more. I figure something was slightly dropping out of tolerance (perhaps the margins were set too poorly or the TL431s had failed - budm has had these fail before.) However, I have never truly located the cause of the problem as I have only had one LG with the problem.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Thanks for your kind help with this mate. I will do a little more research before I jump in and start shorting pins. Its sounding good so far and I will keep you posted on how I do. Hope you enjoy our course.

[Baileybum1234]

Re: LG-50PQ6000 clicks and clicks and clicks

Well I did the mod just now and the relay clicks on/off once so thats an improvement. I will fit it into the TV tomorrow to see what happens.

Just was looking for components in common to both those optoisolators and there is one electrolitic capasitor. I have lost my DVM so cant test it grrrrr.