Sanyo LCD37XR8DA have lvds problem

[maxvalutech]

This set at first displayed all vertical coloured lines but at first touch of buttons screen came good. After a day the screen scrambled again so I pulled back off and found cause was to do with lvds connection to tcon. Gave it all a good clean and then OK. Tested for a day with back off then 2 days assembled and all good but at next switch on verticals again. The lvds has to be set in its tcon connector at just the right place - ANY slight movement and problem returns. The lvds itself looks OK and I have cleaned tcon slot as best I can. Taping hasn't helped and can't sell set yet as moving it will likely bring problem on. Anyone have a trick up their sleeve for holding this cable in place.

[freakaftr8]

Re: Sanyo LCD37XR8DA have lvds problem

Did you look to make sure soldering connections from LVDS socket to board are ok? Ove had this problem before. LVDS cables I clean with an eraser.

[budm]

Re: Sanyo LCD37XR8DA have lvds problem

Did you also remove, clean, reset the cables between the LCD panel and the T-CON board?
The T-CON board mounting screws fro GND are tight?
I cannot see how bad connection on that LVDS connector will cause vertical line just in one section of the screen, and I can also see a black horizontal line (https://www.badcaps.net/forum/attach...9&d=1513824872) in the middle of the screen which cannot be caused by bad LVDS connection. I do not think the problem is on that LVDS connector.
How about if you flex the panel?

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Very good replies. I will take the tcon out again tomorrow and check solder joints on connector. Have had the tcon to screen connectors cleaned at tcon end but will do again. The screen is usually full of lines or lines and colour patches but at times is like shown in pic and that then moves from one area to another or doubles up etc more so when remote button pushed for menu or source. Have also seen full white screen. The thin horizontal black line also moves - was first about 3" below top then went to a quarter down then halfway!! Picture is perfect when set working correctly which it has done now for last 4 hours!

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Well took the t-con out again ran the hot iron over connector pins gave whole board and all connectors a good clean and check and then reassembled as shown in pic. Put t-con metal cover back and screwed in tightly. Set TV up and switched on - this gave me 4 rectangular vertical panels across screen but they started about 3" down from top and were dark/light/dark/light across screen but with verticals in them. Tried to get a pic but then the program pictures came in and all good. So I am now thinking I may have been barking up the wrong tree as when I stop and think it through it has always been when switched on from cold that the problem shows up and three times at least has cleared within seconds - its a bit like the main is slow in processing the signal to the t-con. The main is also under a metal cover so time to pull it out and have a look I think.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Pulled main board which is enclosed except for connectors inside a four sided metal box. Nothing much to report except for hot mark on celluloid sheet underside protection for board (see pic). The ic must get fairly hot but it looks quite OK. Gave it all a clean up and put a small dot of cooling goo on ic then closed up and refitted board ensuring all connectors snug. Closed set up too as won't be doing much now until new year. Put it on test where it started properly and operated normally and has done so for a number of starts. Only odd thing I have noticed prior to this is that I set the screen for a standard picture but now and then I see it changes to dynamic so have selected lock programs in menu to see if that will hold the standard setting.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Pic for above

[R_J]

Re: Sanyo LCD37XR8DA have lvds problem

That looks like it might be a small voltage regulator ic, it might be worth checking or changing the few elec. caps. around it.
Could it be ic # N802? if it is, it is the 1.25 volt regulator. if that line is not filtered properly any noise/ripple induced by the reg. ic could confuse anything connected to it.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Thanks R_J I think your right with the number. I did look at the board number but didn't write it down I tried to read the ic inscription but too small for me even with magnifying glasses. It shows no sign of distress and is an 8 leg type. Will continue testing the set on and off for several days.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Have used this set a lot over the holiday period. Only three times did I see the screen pattern come up at switch on before the Sanyo logo once very briefly indeed but then the second time it was on just long enough for it to dawn on me that it is actually a black and white test pattern! Where it is coming from I really don't know. The set went well at all times once started but did still change display from standard to dynamic and this seemed to be when switched off at pp for some time. I have a universal remote and did get service menu up by selecting AV (source) then 2, 5, 8, 0. I changed backlight setting from 100 to 70. When I put main board back I did put a new piece of tape over celluloid black spot so will check to see if this hot spot is still a problem before I market the set.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

This set continues to be a problem. Left it unused for several days then when I switched it on the Sanyo logo didn't come up but a sequence of lines etc did. This is shown in pics. The vertical lines appeared to change colour and move in line with picture changes (had another set going alongside it) until what looks like a test pattern came up this time coloured and that then remained stable until switch off. Sound was coming through OK all the time. After about 7 attempts the logo came up and set operated normally for hours until it was switched off. Haven't had time yet to pull apart again but its an interesting chase I have with this one.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

The pics in sequence...

[freakaftr8]

Re: Sanyo LCD37XR8DA have lvds problem

I would say faulty lcd panel. When it warms up via the CCFL tubes the heat makes the bond on the driver tabs connect. When cold, bad connection.

[dskall]

Re: Sanyo LCD37XR8DA have lvds problem

The faults seem to be random.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Got back to this set today mainly to check if "hotspot" still showing under main board but no sign at all of any overheating. Gave all a good check and clean then tested. Again patterns showing on screen at start up before Sanyo logo. Where they come from I've no idea. Tested regulators etc on t-con and all seems OK. But due to being able to buy a t-con for $21 delivered have decided to give that a try if for no other reason than to see the outcome. Further report in due course.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Well got the t-con and fitted it. Horizontal lines now and then at start confined to bottom half of screen and lasting only a second or so before Sanyo logo and set operating normally. However, now signs of solarization I believe with shadowy areas coming up greenish and some other weird effects at times. This is only bad component I have received after many various purchases but in defence of the seller while board number etc is the same the sticker in very fine print differs from my original - perhaps a different screen?

[nomoresonys]

Re: Sanyo LCD37XR8DA have lvds problem

So maybe you just need the right tcon board.

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Have put original t-con back in and started set cold several times with all going well. Have now adopted a go-go policy with these older sets and that is they either go properly quickly or they go west quickly (otherwise known as "go or throw" !!)

[nomoresonys]

Re: Sanyo LCD37XR8DA have lvds problem

Wonder if your firmware needs reapplied?

[maxvalutech]

Re: Sanyo LCD37XR8DA have lvds problem

Just to finish this post I had sold our bedroom set (wife watches overseas sport cricket tennis etc) so replaced it with this set. I found that to get it to start normally to just leave it in standby for about 20mins. Other than self switching from standard to dynamic mode it runs well with a good picture. My best guess is that some component probably on tcon just needs to warm up to perform properly.