Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

If the picture is not flickering, it is rare for the STK IPM to be bad. It looks like you may have at the very least a bad upper buffer, but possibly the lower one is bad too.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

I still think I got YMAIN/YSUS issues as well, I think that STK type chip under that big heat sink got issues they always go out on the LG hybrid boards but those are easy to check, you just start unplugging till the power board stops cycling

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Ok I got half the screen but its all messed up, here is a pic of the set with the upper buffer removed... The TV is upside down in the picture

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

I'll try that, lets see what happens...

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

The manual is wrong, a bad buffer can sometimes cause that symptom.
The buffers on these sets are notorious for going bad, and sometimes taking the Y-main with them.
You can try with only the top or bottom buffer and see if the set shows half a picture.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

I did the drag the test lead across the buffer connections to the screen. and on the upper buffer board I found most of the pins leading to the top chip are shorted to ground, I know that this buffer is bad but I thought when a buffer is bad just a part of the screen is gone??? That is what the troubleshooting section of the manual says.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Ok I'll try the camera shopping...

I replaced the bad cap, it was a 100mf 50v, that didn't fix it and made no changes. Maybe just another problem getting ready to go at a later time. So while I had the boards out I took pictures. the cap that was bloated in the lower left corner by the little transformer. the one just above the big blue poly mylar cap.

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

OK...
For reference, I purchased a high quality Samsung 14MP digital camera capable of close macro shots for £35.00 (approx $50US) from a local second hand shop, if you're looking for a new camera go down there and ask to try them out, bring a laptop motherboard or something down and you'll often find a good compact with good macro capability.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Whoops I stand beside myself, while looking at the many screws needed to be remove I found a bloated cap on the YMAIN/YSUS board ;} go figure. so I'll pull the board and replace the cap and look around @ the circuit it's in... And I'll post up results.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

I give up I 'm just gonna give the customer back this tv and I can't fix it... I'm sorry for wasting your time. I won't ever ask again OK I do'nt wanna disassemble the whole tv just to show you pics of the boards, my camera sucks. I can't make out half of what I take so with that in mind the pictures aren't that functional. If I could take the kind of pics you need to see that would be one thing but like I said the camera sucks

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

OK, can you get a picture of the buffer boards and the Y-main?

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

all the voltages fluctuate a little a few volts but no I don't have to reset a fault by cycling the power or unplugging ect. The screen will flash as long as I leave it powered on.

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

No cycling as it flashes?

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Alright I put the boards back in and found VSCAN and it is -198. So what's next?

so all the voltages are ok

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Vscan = -Vsc and Vset are testpoints on the topmost board.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

I had to remove them in order to get a good pic

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

VSC is on the Y-main/Y-sus board.

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Evidently I got a bad meter, strange readings. I pulled out my spare meter and all the voltages are close to the panel sticker.
Panel sticker says VA 70v VSC-190v VS 201v VA 84v VSET 195v
My meter says VA 70v VS 201v VA 87v VSET 199v

I can't find the VSC to test???

[tom66]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

Can I see a picture of each sub board?

[high-tech]

Re: Samsung Model HP-R4272V/XXA 42in Plasma screen flickers

My secondary findings are still the same... the voltages coming off the sub power board to each SUS board on the VS pins is not the same. the main YSUS board is higher than the XSUS board