Samsung 50" Plasma HPT5044 No Picture

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Yeah turned out to be a bad mosfet right above the Yfr adjuster. It wasn't fully shorted. I tweaked the Yfr/Yrr a bit and theres no more sparkles anymore, it looks great!

I'm guessing these buffers should last longer? With a total of 12 IC's than the original 8, I guess there would be a lower load on each one?

As for the blinking LED, I just changed the setting on the Menu so it would turn on only when the TV is on and it stays constantly lit now.

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

Hmm, the failure with this set was the MOSFET failing, due to it being insufficiently sized. The shorted FET then blew the buffer ICs. The buffer ICs themselves are quite reliable, and rarely fail.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

This Plasma wasn't too bad to repair. When I got it I was expecting something like those plasma panels with IPMs on their Ysustain board...

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

You don't see those in new sets, which is good.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Yeah I might try another plasma if I get the chance. Thanks for all the help!

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

Heres a photo, I'm guessing these are the components? Which resistor did he replace, 1 or 3?

Which heatsinks were getting warm before you replaced these parts? Been following this as I have the same problems. Everything looks good. When plugged in lower sink is warm and upper is cold.

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

Well I think the buffers are ok. Have a set of the 6 ic buffers just in case. But not sure I'm doing the test right. As for the y-main I don't know. Only one heatsink gets warm so I think it's shot. But I'm still learning to test and understand the results so who knows. I do have a line on another board here in town. I may try to get it and use the 6 ic buffers. They came from one with a broken panel.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Did you check the mosfets under the heatsinks? It was a pain but I had to desolder each one, take them out, and measure them all out of circuit to find the shorted one.

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

No That's where I ran into trouble. I ruined the x-main that way and had to get another one. I got another y-main today. Now I'm trying to deside which set of buffters to use. The 4ic boards that were in it or the set of 6ic ones that I have. I just not sure of my testing for shorts.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Assuming theres no shorts, It should be fine to use either the 4 ic or 6 ic buffer boards. The one I had, initially had 4 ics on it but I bought the other set that had 6 ics on it to save on costs. But the one with 6 ics worked perfectly on my set.

Just make sure when you do test the panel, that all of the screws are screwed in. I'm still not sure but I think one of the mosfets I replaced shorted because I decided to leave out most of the grounded screws...

[tocold4u2]

Re: Samsung 50" Plasma HPT5044 No Picture

usually when the upper buffer goes it takes the y main,,,,,,but some times u get lucky!! you can leave the bottom buffer hooked up and c if you get some sort of pic,,, on the safe side buy a set of upper n lower boards or you will be fixing the same prolbem latter on down the road !!

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

When I did the test with one board at a time with the old y-main I got no picture with either one just sound. At this point I'm thinking the y-main was taken out by the PS. Or more likely what I did by not waiting to plug the mains back in after unpluging the power.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Are you saying with the new Y-main you just received today the tv still has no picture just sound?

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

No That was the old board. I've got it all hooked up just checking something in the service manual before I apply power.

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

Well that didn't work. Still have sound and no picture. Tried both sets of buffers. I'll have to recheck the volts later. Work tomorrow. At plugin does Samsung go through a prestart like Panasonic? On this one the power button just lights.

[tieny]

Re: Samsung 50" Plasma HPT5044 No Picture

Where did you get your new y-main board?

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

A local recycle place. Just did the no picture voltage check per the SM. Don't have the 207 Vs with the four plugs removed and the PS turned on. Dang I thought I had that fixed. Oh well off to work I'll look into it later.

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

I'll put this here in case someone can use it. The 207v VS and the 63v VA are both very low. The VA is 4.3v and the VS is 0.013v. I've checked the esr on all tha caps but the 3 big ones. I've started rechecking the caps because now I can check the capacitance. I'll pull the big ones this time. The 4 fets on the center heatsink are new. I'll report back when I'm done checking them.

[tom66]

Re: Samsung 50" Plasma HPT5044 No Picture

This SMPS generates Vs/Va on same trafo.

A short on Vs will cause low/missing Va.

[DavidOH]

Re: Samsung 50" Plasma HPT5044 No Picture

I know how to check the fuses with the power off. Both good. But what kind of reading would I get with the power on? How do I check what the volts going thru are? AC/DC? My thought is that this will help narrow down where the porblem is.