2008/9 Samsung LN55A950 Displaying Horizontal Lines

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

VONE: +20V to +33V
VOFFE: -5V to -10V
AVDD: +14V to +18V

Suspect AVDDB to be same as AVDD, not sure though.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

assuming just check with VM ?? no scope needed ? didn't realize wire was covering up one of the test points in pic

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Yep, red probe on wire, black on chassis of TV.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

VONE = +9.7 volts
VOFFE = +0.7 volts
AVDD - +15 volts

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Ok, so that is bad, but we need to rule out the panel. Remove the ribbons from the top of the t-con and re-test the voltages.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

assuming u meant all 4 ribbon cables on top of tcon. no change in voltages
VONE = +10.1 volts
VOFFE = +0.65 volts
AVDD = +15.1 volts

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Yes, those ribbons.

OK, it seems like T-con is defective. But one final check, need to see if panel caused it.

With ribbons out, and power OFF, use your multimeter on the diode test mode and see what the reading is from VOFFE to chassis ground. Then repeat with the ribbons in, power off still.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

VOFFE to GRD is 10K ohms - both polarity
AVDD to GRD is 2.8K ohms.

cables off or connected - NO CHANGE in ohms

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

OK, so there is a good chance the panel is OK.
I cannot guarantee it! but it seems good.

Typically VONE and VOFFE are generated by same circuit using a "charge pump".

Confirm my suspicion in this photo is the bottom left hand corner where VONE is (on the other side of course) and middle left is where VOFFE is?
https://www.badcaps.net/forum/attach...6&d=1397956532

If so can you get clear photos of each area.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

take a look at post #80 - white screen pic. I'm wondering if this set is worth the $100 FOR THE TCON board. The bottom left corner has a dark spot all though the LED lighting is in grid format on these sets. Maybe that dark spot is related to the TCON board ??
I'm gettting the pics for u now.

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

The dark spot is more likely a result of the poor T-con output, backlight being out would only be slightly visible IMO.
$100 is a risk, the panel COULD be bad (no guarantee here - I think it's OK but only about 90% sure) and it could damage the new T-con. $100 gamble essentially.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

had a little fun ! pic show where signals are roughly.

I have seen one of these working - pretty impressive pic. Have a couple SONY BRAVIAs - also impressive pic

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

TPS65167 is the IC which controls the VGH, VGL and AVDD generation.

Check D14 is not shorted/open, it's just above the IC.

If that's OK, then replace the IC... That would be my guess as what to replace, if you feel confident in replacing it, it's available:
http://www.ebay.co.uk/sch/i.html?_tr...at=0&_from=R40

If you want to see a really impressive pic that will blow almost any other model away, Panasonic PZ80 series plasma, from 2008. Or any newer Panasonic plasma or Samsung beyond 2011 (although build quality is mediocre.)

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

Have a sony kdl60ex700 - got it from sony on green blob recall. It is and has been a great set. I got a panasonic 50pz80 plasma last week for free (haven't touched it yet). I'll open it up next week, post some pics.
I'll look at TCON board tomorrow. Probable buy a TCON board - hate to just part this sammy out. I've had bad luck with newer sammys - u helped me on a D550 plasma earlier, never did get it working correctly - parted it out.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

diode D14 (KJH v9) is open. trying to cross it over to an obtainable part

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines



subs BAV99W readily available.

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

can't find any locally - tried to find the mmbd7000. 2 electronic stores locally don't have BAV99W. going to use 2 - 1n4148s. should work

[tom66]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

You can buy BAV99W from Digikey, but it reminds me of when I did this, I also had bad VGL circuit and used 1N4148s to repair it:
https://www.badcaps.net/forum/showthread.php?t=33134
https://www.badcaps.net/forum/attach...2&d=1384906003

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

have plenty of room - I'm going to try 4148s

[ajshoe]

Re: 2008/9 Samsung LN55A950 Displaying Horizontal Lines

no change in voffe - same symptoms. ordered a TCON board - this one is toast.
might have something to do with black heatsink ice cold.