Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

[ksd485]

I have a Samsung LN52A650. The TV has screen artifacts and will repeatedly power cycles when a input source (any of the HMDI, component, and composite) is selected and active (the source device is powered on and providing input to the TV). When an active input is selected the screen will display video artifacts(see attached pictures) and after approximately 10 seconds the TV will power off and on by itself. When in this state the TV will not respond to input from the remote. After a variable number of power cycles the TV may start to work properly or the TV may have to be shut off by pulling the power cable. If the TV works correctly it will infrequently display the artifacts after some period of working correctly and begin to power cycle.

With no input to the TV (sources disconnected or turned off) the TV powers on and "No signal detected" is displayed on the screen as usual. The TV's menus can be displayed and browsed in this state, the remote works and there is no visual artifacts on the screen. The TV can be left in this state for an extended period and no artifacts appear. As soon as an input source is connected turned on and selected as the source in the TV artifacts will appear and the power cycling will begin.

I took it to a repair outfit in town and their diagnosis was the buffer boards between the Tcon and panel. That doesn't make much sense to me, but I have not tried debugging a TV before. Does the buffer boards explain the symptoms?

[awyatt2]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

ln is not plasma no buffer boards, best guess would be bad tab bonds or tcon. sonetimes by a bit of pressure near the top edge of the tv will clear tab bonds. tom 66 would be the one to tell you how to test the tcon.if it is the tab bonds they may or may not be repairable. I was able to fix one out of three, its is still going after a year, the other two had bad components and weren't fixable.

[ReeceyBurger123]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

Even if this was a plasma faulty buffers would be a solid failure. Common issue on these is a loose power connector that goes from Psu to Mainboard reseat it and see if solves the issue.

[budm]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

Can you provide us good clear pictures of the backside of the TV so we can see all the boards, plus the pictures of each board.
"and after approximately 10 seconds the TV will power off and on by itself."
Bad tab bonding (or the so called BUFFER board by the repair shop) will not cause the TV to power cycle. You either have unstable power supply or unstable problem in the main board.

[ksd485]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

I don't have pictures of all the boards but here are the pictures of the main board and the power supply. I will take more pics when I'm home

[awyatt2]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

reecey burger123, buffers would run in the right to left but not always a solid failure, I have a Phillips here with lines across the screen, both buffers are faling. they may not always just go black.

[awyatt2]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

bud, I have the same tv, the power cycling was the resistors on the mainboard and a small tant cap. it didn't have the lines though, just pic dimming and power cycling,as to this is the same ,I don't know. maybe worth a try. the lines or artifacts look like tab bonds to me though.

[tom66]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

Even if this was a plasma faulty buffers would be a solid failure. Common issue on these is a loose power connector that goes from Psu to Mainboard reseat it and see if solves the issue.

Yes, buffer faults can cause both vertical line issues as well as other distortions, they do not always cause the picture to just drop out.

[budm]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

bud, I have the same tv, the power cycling was the resistors on the mainboard and a small tant cap. it didn't have the lines though, just pic dimming and power cycling,as to this is the same ,I don't know. maybe worth a try. the lines or artifacts look like tab bonds to me though.

It may have the same cap failure like the the LNA 500 series with bad C102 on the bottom side of the main board. I do not know which cap on the LNA600 series is.

[awyatt2]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

c102 If I remember right off the top of my head. I took this from shop jimmy's so they are the same power supply. so probally its the same as the 500 series
LE52A558P3FXXU 0001

LE52A558P3FXXU SQ01

LN52A530P1FXZA

LN52A540P2FXZA

LN52A550P3FXZA

LN52A630M1FXZA

LN52A650A1FXZA

LN52A660A2FXZA 0001

LN52A750R1FXZA SQ01

[ksd485]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

bud, I have the same tv, the power cycling was the resistors on the mainboard and a small tant cap. it didn't have the lines though, just pic dimming and power cycling,as to this is the same ,I don't know. maybe worth a try. the lines or artifacts look like tab bonds to me though.

If the issue was the tab bonds, why would the artifacts only appear when using an input? The "weak or no signal" and TV setting menus appear perfectly.

[budm]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

I look at the pictures of his main board on shopjimmy but the layout is not the same as the 500 series.
He may try heating with hair dryer or cooling the main board to what happen.

[Terryfictv]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

The issue with C102 and C131 relates to main boards BN41-00975A,B and C.
Many, but not all LNxxA5XX "A" line Samsung LCD TV's have that particular board type.
C102 is on the bottom of the main board and C131 is on the top. The proper replacement part is a 47mf/10v TANTALUM capacitor. The original has AS7 on it and observe polarity ( the stripe is positive ). Failure symptoms typically are power cycling and sometimes a loud screech in audio. Other intermittent, "after hot" problems are possible. Use heat and cool to verify.....
600 series = heat & cool main board IC's ( mostly heat ) to decide if you
should replace the main board.

[ttcole1254]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

This repair worked wonderfully for my Samsung 52" LN52A550P3FXZA LCD from 2008. I believe a bad cap on the power supply board started this mess, at least for me. Could have simply been a coincidence though. The problem got bad fast until I replaced the power supply cap and all like it, thinking that was the culprit. The problem didn't get worse for a month until I had the time to complete the repair. I replaced both c102 as well as c131, however the originals had slightly different markings. c102 had "NEt AS7" written on the cap, and c131 said "NEv AS7." On my board c102 was not marked, but the part is easy to find as it looks identical to c131 just on the opposite side of the board.

I used DigiKey part # 399-10532-1-ND, a 47uF 10v Tantalum Polymer cap at both locations as referenced in another post. Word of caution though, it is a little tough to get both pads seated correctly on both caps. The first time I completed the repair, c131 had one leg not making contact, and the set would power cycle without any activity on the screen. If this happens, reflow the pads of both caps, and use a small flat blade under the cap on both sides to pull up very lightly to ensure it has good contact with the pads. If it moves at all, keep reflowing it or reposition the cap and try again.

It works great now, and the picture is actually a lot more even now. Before, on a solid color you could see shadowing/artifacting on screen. Now the only thing left is a small collection of purple looking pixels near the right bezel about half way up that's been there through the failure. Could this be damage from lifting the set by the bezel, or more likely a damaged panel or other electronics? I can take some photos if needed. It's only really visible on gray/black backgrounds.

[alfonsoreyesd]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

quick question i have to get done this tv soon with same symptoms i do no have tantalium cap,, i used a regular electrolitic cap and works fine at least for now,, question is will i be ok with this repair or still i have to get tantalium ?

[jerrold1981]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

The issue with C102 and C131 relates to main boards BN41-00975A,B and C.
Many, but not all LNxxA5XX "A" line Samsung LCD TV's have that particular board type.
C102 is on the bottom of the main board and C131 is on the top. The proper replacement part is a 47mf/10v TANTALUM capacitor. The original has AS7 on it and observe polarity ( the stripe is positive ). Failure symptoms typically are power cycling and sometimes a loud screech in audio. Other intermittent, "after hot" problems are possible. Use heat and cool to verify.....
600 series = heat & cool main board IC's ( mostly heat ) to decide if you
should replace the main board.

***
I found a trashed Samsung LN46A580P6F, look in great shape and I had my van, so I decided to pick it up.. Owner came out and said it worked intermittently... I powered it in my shop and only clicks, once in a while a loud noise would occur.... So I opened it up & found the cages around the PC boards were gone... I said to myself, someone was here before me.... Poked around didn't find anything obviously wrong.... Went to the internet and found out about the Samsung Cap issues... I found that the Caps had already been poorly replaced... Cleaned it up, still no joy... Applying heat to the power board, did not do anything, but when I applied it to the main board, seem like the TV would work for a period of time... Narrowed down the section to apply heat, was right around the top left corner, right around the C102/C131 area... Replaced the caps the next day and been working ever since.... Thanks very much !!!

[budm]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

https://www.badcaps.net/forum/showth...msung+LN52A%2A

[ttcole1254]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

Figured I'd update the thread, the TV is still going strong to this day and it's used every day very heavily. I had an issue a couple weeks in where one of the caps lost connection to the board because of the different footprint of the caps themselves, but a quick reflow and additional solder added and it's been fine ever since. Both C102 and C131 were replaced as a precautionary measure.

[Shane711]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

I believe the Cap that would cause the power cycling on these TVs would be C132

[Shane711]

Re: Samsung LN52A650 Visual Artifacts & Repeatedly Power Cycles

OK, so I had 2 of these TVs power cycling. I changed out CAP C132 on both main boards and then played a 2 hour movie with each main board and there is no power cycling. Success!