Samsung HP-S5053 Plasma Burnt Buffer Scan IC

[matt1212]

Hello,
I have a Samsung 50" Plasma (HP-S5053) where the picture cut out but sound was still functional. I took the the TV apart, following the service manual. I checked the Vs and Va to ensure they were in spec, which they were.

I decided to check the Y Main Board, as I have read this is usually the cause of my issue. On this Y Main I found one diode (D5005) that was shorted (Showing only ~0.072V drop with Diode Check on DMM). I will order and replace this diode.

While removing the Y Main I was forced to remove the Y Main Scans. The Buffer Scan IC located on the lower Y Scan appears to have shorted through the top of the plastic case of the IC. I will also replace the lower Y Scan as I assume this is also defective.

I am wondering if this diode shorting out caused the Y Scan failure or the other way around. Is there anything else I should check? I fear I will replace these parts and will encounter the same issue. Any help/resources/direction would be great.

[matt1212]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

Also if there is a recommended source for the necessary boards please let me know. How often do TV's with Y Main/Scan issues usually last after repair?

For clarification, pictures 4 and 5 show the chip that appears to be damaged and the burnt piece of plastic that separated the top of the chip from the component inputs on the side of the TV. Picture 2 shows the location of the diode I measured as bad, and picture 3 is a closer view of just the diode (D5005).

[mmartell]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

That diode reading may be erroneous due to the low ohm resistors nearby. Remove the buffers and run the set. Is there a steady green led lit on the ysus ?

[zacheriaj]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

R5000 looks a bit toasty..

[matt1212]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

Okay guys, sorry for the delay I've been really busy with school. I'm an EE in my senior year. I tell you this so you know I have a chance at troubleshooting this but I am humble enough to admit I have limited experience with consumer electronic troubleshooting.

Mmartell, I hooked the Y-main back up with the buffers disconnected. After powering on the set I do not see a steady green LED lit on the Y-main, although I do no know where this would be located nor do I see a LED on Y-main. If you could point me in the right direction on this that would be great. I was able to find this video on Youtube http://www.youtube.com/watch?v=R5mYK...K73BbOxfteY5Gw. Following his instructions I read 30k-40k Ohms between ground and the output pins on the Y-Main with the Y-Buffers removed and 30 Ohms with them disconnected. This still leads me to believe the Y-Buffers are the source of the problem. Are their more tests I can do to make sure the Y-Main is 100%? (My diodes check out unlike the ones in the video).

zacheriaj, I think the picture just made R5000 appear that way but I'll consider disconnecting a leg and checking.

[tom66]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

The LED in question is in the bottom right corner of the Y-main. It is right near a ribbon connector which comes from the control/logic board (usually buried under the main board on these older plasmas.)

[matt1212]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

I unfortunately still do not see an LED on the Y-Main, especially around the ribbon cable. I can see the whole Y-Main board.

I do see one solid LED and one flashing LED on the Logic, however this is under the main board so I cannot tell what these lights signal. Any chance the status light in question could be on the logic board? Or is there definitely an LED on my Y-main? I've looked pretty hard for this...

[matt1212]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

The upper Y-buffer has no short to ground but the lower Y-buffer does. This is consistent with the visible burning on one of the ICs on the lower buffer. I reconnected everything with the bad lower Y-buffer removed. The top half of the picture is visible and clear, with the exception of one ~1" black bar running vertically through the screen.

Does this mean the Y-main is 100%? If not someone please give me a better way to test the Y-Main.

[mmartell]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

Indeed it sounds like your ymain and upper buff are good but post a shot of the screen with the vertical band as you may have other problems.

Have you seen this tv working before ?

[matt1212]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

So I finally got around to replacing the lower Y Buffer I ordered. Seems to have worked, although the 2" vertical black bar still exists (bar is black with a few pixel-width red, green, and blue vertical lines within it).

I seem to have nailed it down to the an exact ribbon cable along the bottom of the PDP, coming from a board the service manual calls the E-Buffer. Running the TV with this cable unplugged just turns the same bar a different color. This ribbon cable does appear to have an IC built into the cable, although I see no visible damage to the cable/IC. I have read many places about how this ribbon cable isn't replaceable. Interestingly, the bar still appears with the E-Buffer board power unplugged.

My questions are:

(1) How can I distinguish between the problem being in the ribbon cable, an issue with the E-Buffer board (although I checked out the IC's on the board and they all give the same readings as the IC's of the other two working boards), or a blown gas cell in the panel?

(2) How "impossible" is it to replace this cable? I have access to high-end soldering and hot-air reworking tools, and consider myself highly experienced with soldering/rework. I also would consider cutting the cable between the IC and the PDP and attempting to attach a new one. Would either of theses ideas work?

(3) If so, is the ribbon cable insulation plastic or more like a kapton (able to handle heat)?

(4) How would I find out what the IC on the ribbon cable is? I don't see any markings.

[newtothis]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

Most of us here have extensive soldering equipment (HA, IR, Irons etc) but none will help with COF cables, It is done with pressure and pulsed heat... The pressure bar must go from ambient temp to 180c in 3 seconds flat... hold it at 200c for 2 seconds then cool then in 2 seconds... this has to be done at precise pressures for it to work.

If that COF is dead you aren't going to be able to repair it. Sorry

[matt1212]

Re: Samsung HP-S5053 Plasma Burnt Buffer Scan IC

yea, I've never soldered on flex circuits and was unaware of this difficulty. I'm still open to ways to determine if this is definitely the cause of the problem. I found it odd that the line still existed with the E-Buffer board power disconnected (though the signal ribbon cable from the logic board was still connected).

Also, if anyone happened to have one of these sets around broken I'd be very interested in purchasing a few of the ribbon cables clipped off of the PDP for the right price.