Samsung HP-R5052 snow at top and bottom of screen (pics)

[tom66]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

This waveform is more or less correct except the ramp down is too long which is causing your overdiffusion, I think.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Looked to be about 100ms? What would be best?

[tom66]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

This is the set dn ramp, it is too long.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

I will attempt to adjust it to 150-200ms

[tom66]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Microseconds = us or µs. Not ms.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

sorry, oscilloscope newb, even if this TV doesn't get fixed, I've already learned a lot...stick with me, I'm appreciating all of this!!!

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

I rotated the YRR pot to it's absolute max deflection and the best I was able to get is what seems to be 150us... Image is still terrible, adjustment of the other pot puts off the colors

[tom66]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Some improvement though? I suspect the YRR circuit is bad, but not sure how to fix that.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Load the parts howitzer!

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

well, no joke...found a board on fleabay for $40... claim is meets or exceeds manufacturer's specs, but I take that with a grain of salt!!! So long as it doesn't blow out the buffers, I'll accept the risk. Once the old board is out, perhaps I'll set it on a table and see if I can't find any bad bits and pieces.

[freakaftr8]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

that sounds good but before you Install the buffers to the new board test the -vsc and vs can voltages.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

that sounds good but before you Install the buffers to the new board test the -vsc and vs can voltages.

The board arrived today. I'll install it, connect the data cable, and the power. I'll leave the buffers out for now and check all voltages. If everything checks out good, I'll put in the buffers. Suppose I should check the waveform as well?

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Hm.

Well, I replaced the Y sustain board. Following replacement, prior to installing buffers, I checked all panel voltages. All checked good.

Powered down, installed the buffers and turned the TV back on. No Joy. Problem still exists.

So, problem does not reside with the Y-sustain.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

I had an X-Main board here from a philips... Figured, the discrepancy doesn't match, but if I don't try it, it'll be it. It wasn't. Still no joy.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

I wonder about the logic board, and I suppose it's not unheard of that the discrepancy would exist with or without the test pattern displayed. However, the logic board from the Philips is a Rev A1 while the Samsung has an A2 in it. I know it's not recommended to use mismatching revisions, but for this instance, since it's already in hand, at most I believe it would be my time that is wasted...

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Well, what I ended up doing was taking the TV's old Y-Sustain board and both its upper and lower buffers and put them into a Philips that's been laying around dead for quite some time. At least the Philips is up and running now.

Who knows what's up with the Samsung. Logic board perhaps? Either way, it needs upper/lower buffer boards plus whatever is needed to fix the snow issue.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Ok, well... I spent some time and frankensteined the TV back together. I was able to isolate the problem down to the logic board. I found a logic board on fleabay cheap enough, but now I'm without buffers.

Hopefully at some point a set of buffers comes around.

The boards in this TV are revision A2. There's no white connector between the two. Does anyone know just how compatible the A4 is with the A2? The A4 has the white connector between the boards... The sustain board is a A4... It's working fine with the A2's in there.

[2dbit]

Re: Samsung HP-R5052 snow at top and bottom of screen (pics)

Well, unless I am not using proper keywords, I have not found any info regarding the installation of a matched set of later revision buffer boards working or not. I imagine it should be ok, especially with an A4 sustain board in there.