Samsung HP-T5064 replaced top buffer IC now I'm stumped

[freakaftr8]

hey all well I just got in this Samsung with the usual shorted top buffer IC on the upper buffer board. Replaced and I have a really odd white maldischarge picture. Oddly on the left side of the screen the left quadrant is white and presenting these vertical stripes. I went ahead and ran the self test by jumpering pins 5 & 6 on control board and I could tell on the right side the colors are flashing I can see them in the center but on the left side is completely white with vertical stripes. Taking a chance I thought it was a control board issue I had an extra one and its doing the same exact thing so it's definitely in the Ysus. I can disconnect Z sustain and I can still see the picture doing the same exact thing. Im getting -190v on vscan. All voltages are present on power supply. Also cannot locate any shorted components on ysus. Have any ideas?

[Shinju]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Just curious, what are your ZSUS voltages?

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

you mean VS voltage? It's spot on

[tw2005]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

I was thinking buffer issue maybe still a short on the buffer board. Was the ymain repaired? They usually fail together.

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

no I figured I would intend on repairing the Ymain as I've found quite a few shorted it in the past but this Ymain is so far testing fine no shorted MOSFETs no shorted diodes and of course I don't have an oscope so I cant test wave patterns but as far as testing is gone I can't find anything shorted I have unplugged just the upper and lower and it presents the same maldischarged white picture

[tw2005]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

So you can get an image with just the lower buffer as well?

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Yes. White like the top and I know that's not right it should be all black or dim just Showing that the panels charge but no picture

[mmartell]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Strange fault makes me think the E and F buffers are to blame ? Are the ribbons connected at the bottom of the screen ?

Also in my last batch of fe3407 ics from China five had some of the address lines shorted to ground. Not out of the realm of possibility you have a bad ic though I can't say it would necessarily present this way but maybe worth checking out.

[mmartell]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Just reread your last post about running only bottom buffer by itself so I guess your ic is not to blame but still worth noting.

[Shinju]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

you mean VS voltage? It's spot on

VE, test point should be on the Z board.

[tw2005]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Yes. White like the top and I know that's not right it should be all black or dim just Showing that the panels charge but no picture

Same result with both boards, makes me think ymain may be worth looking at again.

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Ok. VE is running at 92v on zsus. Spot on with panel label. I tried another buffer board. Same results it's gotta be the ysus. Being that the left side of the screen is totally unresponsive and just white with maldischarge and vertical stripes and right side I can see the image in test mode behind all the maldischarge makes me wonder I'd some discrete components failed at the ribbon cable output to the control board.

[tw2005]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Ok. VE is running at 92v on zsus. Spot on with panel label. I tried another buffer board. Same results it's gotta be the ysus. Being that the left side of the screen is totally unresponsive and just white with maldischarge and vertical stripes and right side I can see the image in test mode behind all the maldischarge makes me wonder I'd some discrete components failed at the ribbon cable output to the control board.

Has the SMD B20NK50Z transistor been checked

I have a bad ymain with 2SK2837 , B20NK50Z and 88N30W bad

680uf cap also goes too on these but my experience really is limited to just find bad 88N30W fets blown with a bad upper buffer.

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Well checked those components again and they test ok.

[tw2005]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

I guess you don't have another samsung or know anyone with one that uses the same ymain for a swapover to test in a known working TV?

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

I wish. Just have a few 5054's sitting around. Complete different beast

[KevinCro]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

I had a big headache like this not long ago. It turned out to be the ysus.

[mmartell]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Not understanding how a ysus would make the screen split in half that way... interesting

[tw2005]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

I wish. Just have a few 5054's sitting around. Complete different beast

5054 has same panel. i guess they all have blown ymains and buffers

[freakaftr8]

Re: Samsung HP-T5064 replaced top buffer IC now I'm stumped

Yes 5054 is same panel but uses different buffers and ysus. on the 5064 the buffers scan Every other line kind of like how Hitachi panels Run. Where the 50 50 for the buffers control individual lines within set displacement of the area. The 5054 also uses IPM modules.