Toshiba 50HP66 (LG) Digital Board or Main Board ?

[mmartell]

Set comes on fine but displays coloured verical lines where I'm guessing there is text. The lines move to the left and right depending on button pushes but never cover the whole screen which remains lit but black.

I want to run the auto-gen patterns.. can anyone spot where the jumper block is ?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Digital board courtesy of ShopJimmy...

[Shinju]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

My guess would be the 6 pins here.

[tw2005]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

could it be that you have in fact shorted buffers or the SMD FETS on those buffers are blown which is also a common fault. Same as a LG 50PX5D and others around that time looking at those boards.

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Ya I did some reading and saw that as well. I would never have thought Y buffers could cause this type of fault ??

There seems to be only one connection to the buffers from the sus (and a daisy-chain to the lower buff). Disconnecting the cable gives the exact same fault. How can there be anything on the screen with the buffers disconnected ?

[tw2005]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Good question?? Got me. Maybe disconnect them fully, not just the multipin lead?

Check out the copell blog. I'd still sus out the buffers as shown, can't hurt to prove either way if they have an issue or not.

http://blog.coppelltvrepair.com/2010...-lines-in.html

https://www.badcaps.net/forum/showth...ht=6871qdh089a

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Lower buffer is shorted. Crappy pic but it says "Digital Signal Strength is Low".

[tw2005]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Lower buffer is shorted. Crappy pic but it says "Digital Signal Strength is Low".

cool, that explains the width of those lines. last time i saw something like that was the " no signal" which is much narrower and what the LG says.

So is it just the FETs or a whole buffer board to sort it out?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

The first fet I removed cleared the short between the gold contact pads. I guess it's advisable to replace all three since they are in parallel ?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

I replaced the three fets on the lower buffer and the set fired up and worked fine - for a time.

It began to spaz, flickering wildly then disappearing back to normal as fast as it came. Now spaz is the new normal.

So I'm guessing the sus ipm is shot but I noticed that that on the logic board a new led is lit. In the bank of four vertical leds only the top was lit during operation now the bottom one is lit as well. Is that consistent with an open Sus ipm ?

[capkid]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

How are your sus voltages when the abnormality occurs?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Lol see here..

https://www.badcaps.net/forum/showthread.php?t=43396

I think it's time for a new meter. I do have a scope just need to learn how to use it

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

I have not blown a ysus fuse so if it's one of the ipm's it's gone open. How can I tell which one ? Can I see on a scope which ipm has failed ?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Does this help ?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

This picture issue came and went over the course of a few days. Can an IPM fail in that manner ? I mean, if it went open what could cause it to close then open and then... well you get the idea. Makes me think something else is at play. Should I scope the inputs to the ipm to make sure they are proper ?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Replaced the er ipm on the ysus and back up and running. Am faced with uneven maldischarge - red sparklies around and imaginary circle as demonstrated in pic.

Any ideas as to what could be causing this ? (Apologies for the grade 2 artwork lol but wouldn't show up in a photo)

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

Should have added the red sparklies are only visible when the shaded area is dark.

But I tried to adjust the Zbias pot and though the bias voltage changes I see no apparent changes on screen. I have also scoped B10 to see the output waveform and it doesn't look like the waveform in the jpeg below. Is the zsus ok ?

[mmartell]

Re: Toshiba 50HP66 (LG) Digital Board or Main Board ?

And this from the scope...