Samsung PS-42D5S - LVDS Cable issue

[ocf]

Hello guys and gals,

I got this tv recently, its a heavy monster! Issue is multicoloured lines on screen and general corrupted image.

Everthing inside looks good, TV powers on without fail but still the screen corruption issue. I was the guide below to perform the self test function built in to some plasma panels.

https://www.badcaps.net/forum/showthread.php?p=318461

I didn't get anything on screen after jumpering pins 3-4 and disconnecting LVDS cable.

I noticed that if I gently moved the LVDS cable in to a certain position when the TV was on all the corruption disappeared and screen displayed perfectly.

I've inspected the LVDS cable connectors on the main board and the control board they look good. The LVDS cable doesn't have any visible damage but the lightest movement makes the corruption come back.

If I counted correctly its a 32pin LVDS cable, very short in length approx 3-4"

Are these generic parts, how can I go about finding a replacement to test with?

Kind Regards,
OCF.

[Andrew F. Ali]

Re: Samsung PS-42D5S - LVDS Cable issue

Look at the LVDS connector on the board and see if there are any cold solder joints...if not I would replace the cable....sometimes the cable may have break/s that are not readily seen.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Thanks for the reply, original question still stands, where can I source a replacement. I've checked ebay but no hits for this model and doing a generic LVDS cable search turns up hundreds of types.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

pins on the LVDS are tiny, my hands are not steady enough, I have kapton tape and hot air rework station. Would it be easier to flux the pins, mask the connector plastic and reflow the pins using hot air?

I have very little experience using the hot air, last time I tried removing a HDMI connector from a PCB I ruined pads and junked the board!

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Resoldered the pins, all look good now. Not so sure its LVDS cable now. Previously a slight tweak of the cable would bring the picture back to perfect now after opening the cable to check wires no ammount of fiddling makes the picture good.

I think I damaged the cable further but I cant find any breaks, I've been meaning to test with a multimeter but its so damn small.

I don't want to splash out £30 for one of these cables.

I am still trying to get the test patterns to show on this screen, when I jumper pins 3-4 on control board and disconnect LVDS I get nothing on screen. Can anyone advise on the process to get test patterns on this model?

See link below for pic of control board -

https://spares2repair.co.uk/images/p...20MAINASIC.jpg

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Tested cable, good connectivity on all pins. The lines on screen still change/disappear when flexing the mainboard.

Could be a cold solder joint, does anyone have previous experience with an issue like this

I've attached images of what the screen displays. Whenever the mainboard is moved or has vibration the lines change.

I'm still trying to get test patterns, any advice on this?

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Good Evening Fellow Badcapers,

I've Still had no luck getting test patterns to display, no matter what combination of jumpered pins and LVDS cable being plugged or unplugged to mainboard and control board, no test patterns show on the screen.

Could this be a sign of a bad board? any vibrations or flexing of the mainboard seem to change the lines on screen and I can no longer get a completely clear picture as I could occasionally get before.

I might try heating the board up a bit and seeing if that makes a change to the display.

I was so sure this was just an LVDS cable issue but after splitting it open and checking all wires + resoldering the LVDS connector on mainboard I am back to square 1.

I feel like the heat I put on the board soldering the LVDS connector pins made the real cold solder joint worse.

There are two small chips next to the LVDS connector, datasheets show these are
CMOS - LVDS converter chips, I'm going to give these some heat tomorrow and see how the display reacts.

Any advice welcome - Peace

[ReeceyBurger123]

Re: Samsung PS-42D5S - LVDS Cable issue

Might be bad Bga solder on control board had this on a similar sammy set.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

I applied some heat to the mainboard and the issues went away for 5 mins. Went ahead and ordered a new mainboard. I hope my actions weren't too rash. On the edge of my seat while this board is on the way now!

[Th3_uN1Qu3]

Re: Samsung PS-42D5S - LVDS Cable issue

Yeah, sounds like bad main processor. The new board should fix your issues.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

I cant wait to get the beauty in!

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Board arrived, first off its the wrong board, not same as pictured on EMOS TV website, it still fits though.

Second issue is shield around LCDS connector and one row of pins were crushed on arrival.
I took pictures and straightened them out.

New board does not work! TV relays click on and off, TV tries to switch on then gives up after 3-4 tries. I hear a burst of static from the speakers when it tries to cycle.

Feel a bit silly after I had my hopes up for a good board like that.

I will be calling EMOS TV's on monday to have a strong word.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Just spoke to EMOS, they didn't bat an eyelid, guy said he would see if there's a replacement available and refund me if not.

I've ordered boards a few times always get the impression that the sellers don't themselves always know the true state of a board.

[vinceroger69]

Re: Samsung PS-42D5S - LVDS Cable issue

Ive brought a few parts from emos and have always received a good service from them luckily all my parts worked so never had to return one im sure you will manage to find another replacement board if you get refunded.

[dick_barton]

Re: Samsung PS-42D5S - LVDS Cable issue

I've not had a problem with EMOS either but have with another UK supplier so I suppose errors are made, however in general my experiences have been positive when buying parts.

[ReeceyBurger123]

Re: Samsung PS-42D5S - LVDS Cable issue

Yes Bga issue then likely, when you get a fully working board might be best to apply a heatsink or two to the hot running Bga chips using thermal silicon to mount them help stop future issues.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

Found another two SMD caps ripped off. Took them off the old board and attached to the new, Being the first bit of real SMD soldering I've done I am very happy with the outcome.

Sadly board is still doing exact same thing as before. I'm sure there's another damaged component somewhere that I'm missing.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

3 more SMD caps and 2 electrolytic replacements later and still no power.

This board is an absolute mess, scratched traces. Cracked components and missing SMD capacitors everywhere.

[vinceroger69]

Re: Samsung PS-42D5S - LVDS Cable issue

unless emos have said to you they dont want the board back i wouldnt mess with it too much as they may refuse a refund (unless they have already told you that you can keep it then its fine of course) maybe find another mainboard from a diffrent supplier if you can and add the heat sink as reece recomends.Im not sure what type of eeprom or spi this board has but maybe worth swopping them over if they dont want the board back.

[ocf]

Re: Samsung PS-42D5S - LVDS Cable issue

replaced another missing ceramic SMD cap. There are quite a few SMD components with chipped edges, going to get started on replacing these in a bit.

Despite the disappointment of receiving a less than working board I cant say no to the SMD soldering practise!