Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

[Dang]

So I need to change the bottom buffer as the last one blew, the YSUS still powers the top one with only the top half of the picture being shown as you'd expect, I did repair the top four Zener Diodes at the output stage of the YSUS as they had all blown, this got it working but the bottom buffer did blow. My question is this, is it just one of those things and a replacement buffer will repair it or could there still be something wrong with YSUS and how would I test for it, I only have DMM?

Samsung PD50Q7.

One thing I should add is I did forget to place down the bridge connector between the two buffers at this time, could this of played a part?

[tom66]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

The bridge connector is important.
Y-sustains drive both buffers with the same signal, so a bad Y-sustain would not cause only the bottom buffer to fail.

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

The bridge connector is important.
Y-sustains drive both buffers with the same signal, so a bad Y-sustain would not cause only the bottom buffer to fail.

OK, thanks for that. So what part does the bridge connector play and if you could please confirm, does it look like the bottom buffer was just bad? if I hooked up another bottom buffer it would't blow? is there anything that can be tested on the YSUS just to make sure? I only ask as the cheapest I can find one of these for(actually a pair) is £54+del which is quite a bit of money to risk on blowing again, thanks once again for your time, Andy.

[tom66]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

Lifting the bridge can cause damage to the bottom buffer, as it carries the data signals to the other buffer signals. There should be no risk, if you make sure to seat that connector properly.

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

Lifting the bridge can cause damage to the bottom buffer, as it carries the data signals to the other buffer signals. There should be no risk, if you make sure to seat that connector properly.

Thank you once again, all I can say is "Oops" but I was given it for free so it's at a £5 so far.

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

Hi again, I have managed to source a bottom buffer board now but I'm still apprehensive about installing it, and trying to find one from a trusted site has taken time, the last site I tried was Cradeal(£54 + delivery), after some research it seems they are based in China and send out duff items which take an age getting to their destination, another site had some guy then asking me to pay via BT to his own personal bank account, I don't think so. Anyway, getting back to the Y-sus, I did also change a through hole fuse located towards the bottom of the Y-sus board, could I have caused an issue there? I know I'm being overly cautious but I just don't want to burn up another, I've waited for what seems an age to get another and I'm not into burning money and really want to see this working properly, thanks for your help once again, Andy.

[Tvbob]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

I have had 2 lower buffer boards (lj41-05122a) short the buffer chips on my Vizio (samsung panel) vp50hdtv20a. They just pop the set shuts down you can smell a little burnt. I don't try to turn the set on until I have removed the lower buffer board. the set come back on with the upper half of the pix. I am using used boards off Xbay The top buffer with panasonic buffer chips are 5 years old. Note BBC America here in the states

[tom66]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

FE = Not Panasonic buffer chips but Fuji Electric.

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

I have had 2 lower buffer boards (lj41-05122a) short the buffer chips on my Vizio (samsung panel) vp50hdtv20a. They just pop the set shuts down you can smell a little burnt. I don't try to turn the set on until I have removed the lower buffer board. the set come back on with the upper half of the pix. I am using used boards off Xbay The top buffer with panasonic buffer chips are 5 years old. Note BBC America here in the states

What do you think causes it?

[Tvbob]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

The Original upper buffer (not pictured) has the panasonic chips
As to what causes it. I would say,heat and age.

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

OK, turned the set on and it works with the bottom coming on but now I see speckles and sparkles on the screen with ghost images of what's been previously on the screen, these are made up of the speckles and sparkles once again, any ideas?

[tom66]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

If image is sticking, adjust Yrr and Vsc/Ysc. If you get sparklies, adjust Yfr and Vset/Yset.

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

OK, the above seems to of died down a little but I still see these speckles, mainly green, also if a dark image moves to where a bright image was then you see the bright image die down, takes about a second but I know it shouldn't be like that, any ideas as to what that is?

[Dang]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

If image is sticking, adjust Yrr and Vsc/Ysc. If you get sparklies, adjust Yfr and Vset/Yset.

Hi Tom66, I'm assuming because they are too high? also any idea where these adjusters are and how I can measure them in real time, I'm sure a DMM will come in use but not sure where I'm going with it?

[tom66]

Re: Bottom buffer blown, YSUS still drives top fine, is the YSUS still OK?

Post a picture of the Y-main board. Yrr and Yfr are adjusted by looking at the panel. Vsc and Vset are adjusted with a DMM.