Plasma TV Y sustain IGBT specs

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tvtech

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Hello

Seeing that CRT is so quite here now... I'm trying to understand Plasma. There seem to be many here still.

The Y Sustain board on the LG I have here is faulty. The IGBT (2 shorted) are Trench gate IGBT. Originals not available.

Anyway, I would like to know from a Wizard here what are the important parameters when choosing alternative IGBT for a Y Sustain board.

From the original parts on the board, I have the RJP 30h in stock. The problem is the other blown one. IRG 7SC28U. It is discontinued long ago. So can anyone tell me the important parameters to search for when looking for a replacement?

Like repetitive pulsed current or max current
Or low Vce on
Or Total dissipation
Or Frequency it can handle when switching
etc.
If someone here can tell me the important parameters I know what to search for.

I'm humble tvtech now lol
thanks
 
Also, Plasma from what I've read has a superior picture compared to LCD. Their contrast is amazing with black being really black and white being really bright. Yes they are power hungry. But some of the last one's built in 2014 are still around. Some manufacturers rated the last lot at 100K hours... that's 8 hours a day for around 30 years.

Gotta try and rescue those left without burnt screens.
 
The IGBT are under the board. The small heatsink fins you see are supposed to help dissipate heat from the IGBT below.

I've the board here I'm busy working on if anyone needs a pic. Camera not so good tho.
 
tvtech said:
Also, Plasma from what I've read has a superior picture compared to LCD.
Click to expand...

In my experience they were better on SD, as their less sharp pictures blur the pixels together, hiding the artefacts from the scaling to make it fit the screen, but not so good on HD.

Their contrast is amazing with black being really black and white being really bright.
Click to expand...

Good black, because of how they work, but only very low brightness levels, again due to the way they work - VASTLY less bright then an LCD.

Yes they are power hungry. But some of the last one's built in 2014 are still around. Some manufacturers rated the last lot at 100K hours... that's 8 hours a day for around 30 years.
Click to expand...

And completely imaginary

The imagined life span is based on the fading of the phosphors (as they wear out), and is derived from the point when the screen gets too dark to be watched any more - however, as they use three colours of phosphor they often fade at different rates, and it's common for the greyscale to drift considerably as they age.

But the figure is meaningless anyway, as the screen will have long since died before - as you're seeing with Y-SUS failures etc. (the SUS boards are part of the screen, not part of the TV.

Incidentally, the estimated life of old LCD (CCFL) sets is based on the same flawed idea, that of the CCFL phosphors fading until they aren't bright enough any more, and just as with Plasma that's not going to happen, the LCD screen will have failed long before that point. But at least the greyscale doesn't drift

As for repairing the SUS boards, there used to be repair kits available (it's not usually just a matter of replacing the FET's, and they commonly fail again if you do), but pretty well all the companies selling TV spares in the UK have long since ceased trading.

Here's one I just googled and found:

KIT412 EBR74825301 / EAX64561401 REPAIR KIT YSUS LG 50PN450B

www.ohmsupplies.co.uk

Just looked a bit deeper, here's a kit for your specific board:

KIT401 YSUS KIT LG 42PA4500 EBR73575201 EAX64286001

CLICK ON ITEM FOR FULL DETAILS
www.ohmsupplies.co.uk

So five parts in that kit.
 
There is nothing worse than treading into unknown territory when you're a bit old. And know stuff/have seen stuff. Hey...watch me take what's left of Plasma and nurture and learn.
 
Thanks Nigel

You're a Technical guy I respect.
I've gotta see what I can do with Plasma.
I'm a bit late to the party though.
regards
tv
 
Q709 in the kit I can't find on the board Nigel.
The rest I believe I can source locally (alternatives with similar or better specs from RS here and in stock).
Q709 worries me.

And I can't find a diagram of the board.
So....

Hmmmmm
 
tvtech said:
Q709 in the kit I can't find on the board Nigel.
The rest I believe I can source locally (alternatives with similar or better specs from RS here and in stock).
Q709 worries me.
Click to expand...

According to a thread on a forum, Q709 is mounted on the heatsink.

LG YSUS EBR73575201 - need schematic and repair kit. - Badcaps

Technical questions about your defective television, projection screen, LCD/plasma, or any other type of video device. When starting a new thread, please put the make AND model of your device in the thread title. Also be VERY descriptive of your issue, that way you'll get the best answer possible!
www.badcaps.net

It's also labelled here:

LG Plasma TV Unable to Turn On-Repaired | Electronics Repair And Technology News

LG Plasma TV Unable to Turn On-Repaired
jestineyong.com

And I can't find a diagram of the board.
So....
Click to expand...

I don't think I've ever seen a diagram of a SUS board?, as I mentioned they are part of the screen and not part of the TV - and for that matter, circuits for the TV itself tend to be fairly lacking.
 
tvtech said:
OK Thanks Nigel
I'm gonna check it out.
Click to expand...

The second link in particular is very informative.

As we were mainly Sony dealers we had very little to do with Plasma, Sony only ever did about one or two models - and initially the service dealers weren't allowed to do warranty repairs on them. In later years we sold a few Samsung ones, and I even managed to once repair a Fujitsu set - I managed to get a manual for it, but it contained nothing (not a single circuit) - but I managed to find a duff capacitor (large blue one, non-electrolytic) on on the PSU board, replacing that cured it. I seem to vaguely recall it was a coupling capacitor, feeding the transformer?, and was O/C.
 
Well Nigel, investigating IGBT is interesting for me. I've learned how they are rated. Welders use them. Some are rated running into a short circuit for a brief time.

So IGBT is the best of both bipolar and mosfet.
And I'm learning. And reading. And learning.

You know my friend, I'm the only one here that has a Technical bone in his body.
 


We have decided to order the kit. Q709 is indeed faulty too. Gonna change all 5 transistors. Thanks for all the help Nigel
 
Aaand the parts arrived at last today. Fitted and yea babyyy

Everything working perfectly
Thanks for the help Nigel
 
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