Sunday, October 2, 2011

When 6871QYH039B fails, should buffers be replaced too? (same for 6871QYH039A, 6871QYH039B)


Hi. My concern is should I go ahead and get the Y-buffers too. Cant a bad buffer blow the new Y-sus? How can I check the buffers without replacing the Y-sus? Do you carry the buffers? Thanks, Geo.

With this particular YSUS, an in fact with most sustain boards made by LG (at least in the 2004-2007 models) I would not worry about the buffers when a YSUS fails for several reasons:
First, the popular concept that when YSUS fails one should look for the buffers is most likely coming from the Samsung designs from the same time period. LG electrical design is similar and does not have the same failure characteristics as the Samsung boards.
In the Samsung cases it's the buffer board that fails first and damages the YSUS.

With LG, the sustain actually fails before the buffer and usually does not affect it.
Second, when the LG buffer ultimately fails (because that can happen too) it does not tend to damage the sustain. It is possible for it to happen, but it is rare.
Instead, when an LG plasma buffer board fails (e.g. in Toshiba 42HP66 or  50HP66) it will typically cause a vertical line as explained in this previous article.

As with any failure it is not guaranteed that it will happen that way. It's just the most common result.
So, in a nutshell, it's not worth worrying about the buffers at the time when you know the problem is in the sustain.
It's not bad to check them, but it would be unusual for them to have failed at the same time with the YSUS.


KSgirl said...

I tested both buffers according to your previous blog and my lower Y buffer failed. MY upper buffer was good. My question is should I replace the failed buffer only, both upper and lower buffers, or all including the Y sustain board?

Coppell TV Repair LLC said...

Isn't the answer to this question the very topic of this article?!

Well it doesn't expand to the Y-Main, but it's quite detailed even as it is.

mxwrench said...
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mxwrench said...
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