-
Hey everyone here
After spending hours of my life with reading posts in this forum and watching Daves Videos i decided to try my luck with an own problem here.
On Saturday I 'luckly' got the old broken Panasonic TX-32LE7F LCD TV from my parents. I hoped i could repair it so i would get a nice TV for my small student-appartment for free..
The actual problem was that the images/frames are sluggish and go into each other, as said above. For example the classic image noise isn't visible as many black and white moving pixels it's more a grey/white 'fog'. I read somewhere that this is called 'Halo-effect' but i'm not sure if this is right.
I also uploaded a video of the Problem on my Google Drive Folder here
Maybe a helpful information: It doesn't matter which signal input i chose and the problem was also present in the TV-Menus, so i think it has nothing to do with the Input circuits themself.
Well, after my parents brought over the TV on Saturday i checked if the problem is still there and yes it was! So i opened the back to check for failed caps or burned fuses (As in one of Daves Videos). But nope nothing. To check the voltage rails i turned the TV back on but somehow the problem was gone.
I thought i might have touched one of the connectors inside so i jiggled on all the connectors again to see if anything changes but again: nothing, everything worked fine, so i reassembled everything.. Well i wasn't sure about this "miracle".
The rest of the Weekend the TV worked fine without problems (i switched it on and off for several times) On Monday also no problems, even after a pretty long "The Matrix" DVD Marathon^^
But then, on Tuesday Morning as i turned it on.. baam: the problem came back. Actually i expected something like that because i haven't fixed anything on saturday. Of course i opened the TV again and measured everything (again), this time also the rail voltages (3.36V, 4,92V, 24,05V) but nope everything seemed to be fine. I unplugged all the connectors cleaned them with contact spray and Cotton swabs, measured the temperature of the image processors and heatsinks on the power board but nope.. This time nothing changed as i turned it back on again. The Problem was still there and now i'm out of ideas, that's why i wanted to try my luck here in the EEVBlog Forum :$
There are also some pictures in the Google Drive folder above.
Thanks in advance for any ideas!
Greetings from Germany
morxw -
Set your
to AC mV and measure ripple, not ideal for the job unless it has a good frequency rating, but better than nothing. Scope would be better.
Report back.
-
It may well be the ribbon's connecting the TCON board to the screen,
just the act of laying the screen on it's face may have been sufficient to
temporarily fix the problem by putting pressure on the surrounding
face plate and in turn the ribbon's.
Turn the tv on and with your hand gently work your way across
the top facia above the screen and press with your thumb until
you notice a change, this is the first thing to try before pulling the
back off.
Muttley -
Set your
to AC mV and measure ripple, not ideal for the job unless it has a good frequency rating, but better than nothing. Scope would be better.
Report back.
Wow thanks for your quick response!
My tells me:- 0,5mV (max 0,8mV) ripple at the 3.3V Rail
- 6,8mV (max 8mV) ripple at the 5V Rail
- 17mV (max 20mV) ripple at the 24V Rail
Btw. i measured these values with the internal analog tuner as signal input (white/black image noise) and highest backlight setting, i thought this would draw the highest current/cause the highest ripple.
-
It may well be the ribbon's connecting the TCON board to the screen,
just the act of laying the screen on it's face may have been sufficient to
temporarily fix the problem by putting pressure on the surrounding
face plate and in turn the ribbon's.
Also thanks to you for your quick response!!
Mhm i just tested this (with the preasure on the surrounding face plate) but it doesn't change anything on the screen. I probably have to disassemble the boards and the shielding to have access to the TCON board, where the connector from the mainboard goes in.. Let's see if i can find anything there..
-
First of all: Sorry for my 'tripple Post'.
Meanwhile i've disassembled everything this far, that i could reach the TCON-Board. (Uploaded some Pictures here)
I tried to softly jiggle around on the Flat Flex Cable but it hasn't caused any changes, not even for a quick moment..
The FFC is pretty short and is connected to another board on the edge of the TV (might be visible on the picture bellow) but i can't really reach this board without taking the entire housing apart
The model number on this board says "320WTS2LV2.6" which seems to be the board where the actual panel is connected to. I only could find this Russian Forum entry where this board was mentioned but i don't understand much, the google translation from russian to english (or german) isn't that great and i don't even know if this helps me in any way. (Just wanted to mention this forum entry)
- morxw
-
Sets where the fault vanishes when warmed up may be temp related and need hot air or a can of freeze spray to diagnose. Caps, voltage regulators, IC's can all be affected, solder joints, panel bonding tabs in some cases.
They can be quite tricky to find but the key is if the fault is reproducible. You need to work very methodically over a small area, constantly checking if you triggered or resolved the fault before moving on.
-
Sets where the fault vanishes when warmed up may be temp related and need hot air or a can of freeze spray to diagnose. Caps, voltage regulators, IC's can all be affected, solder joints, panel bonding tabs in some cases.
They can be quite tricky to find but the key is if the fault is reproducible. You need to work very methodically over a small area, constantly checking if you triggered or resolved the fault before moving on.
I'm not sure but i don't think, that it's temp related. I already tried to heat up/freeze the main image processing IC's but there was no visible difference.
Meanwhile after i've disassembled the TCON-Board and reassebled everything again yesterday, the problem got even worse. Now the image is realllly sluggish and it needs quite a few seconds more to completly fade out the previous image. (especially from white to black)
Now i'm a little confused, because i wiggled around the flat flex cable and everything but that hasn't caused any changes so yeah, shouldn't be a bad connection or what do you guys think?
Seems to be something between the Mainboard-TCON Cable and the actual Panel(-controllerboard).
There are still TCON-Boards available on ebay/aliexpress for this model but i would actually prefer to be sure that this is definitely the Problem (before i spend money on these "maybe-things".)
Could also be something with the board in the edge of the housing that is connected to the TCON board, that i've mentioned in my previous post..
Edit: This ist the board that i've mentioned (320WTS2LV2.6) Shop Link with pictures (Another picture below) (Yes i've seen that the one in the Link and on the picture is the "320WTS2LV2.7")
-
G,Day morxw,
Put the unit upright, connect an input, turn it on then grab each top corner and slightly contort the screen looking for a sweet spot whereby the picture may reveal, be careful of getting zapped.
We are trying to establish if it is a problem with the edge ribbon connection's on the top of the screen.
Also just re- edit or add to your existing post
-
Hey Muttley,
I reassembled the TCON board and everything else yesterday (Except the plastic cover on the backside of course).
-
lvds decoder problem scheck graphic near nlvds or dp near lcd screen mesure 3.3v at the of every output to lcd nap if all ok change lvds cpu and it will work
-
"sluggish" = broken connection, with only weak capacitive coupling allowing the signal through.
-
This set uses a Samsung panel (hmm - most Panasonics of the day used Hitachi-Panasonic IPS Alpha panels, so I'm guessing this was a budget model) which is prone to suffer from a tab bond failure, the top left bonding on the panel fails causing a blurry/slow or dark-tinted image.
-
lvds decoder problem scheck graphic near nlvds or dp near lcd screen mesure 3.3v at the of every output to lcd nap if all ok change lvds cpu and it will work
from the description its tcon/panel problem, not scaler?
you can forget about 20 yuan board you linked, unless you have magical panel bonding equipment to solder tabs to glass
only russians are hardcore enough to even attempt fix on this level ( http://monitor.net.ru/forum/topic375748-96.html )
might be simply a cracked cap on the main tcon, open tv again, take off metal can from the tcon, use your finger to probe around while TV is on, or take tcon out and check every cap, or measure voltages on tcon while its on
or buy another tcon if its cheap enough
my first bet was bias voltage, but this tcon doesnt have AS15/AS19 chip that often fails -
Sorry for my late reply guys.
Thanks for all your ideas and information. I decided to buy a new T-Con Board + Flat Flex Cable (in case there is something wrong with the cable as well (in relation to amyk's post)).
They cost around 30 bucks so hey let's give it a try.
If this doesn't work, it's done anyway because as Rasz already said, for reaching the actual panel and the "Panel Board" i would have to take apart the whole tv (the panel is glued to the plastic frame and i couldn't even desolder the board from the glas panel
) This set uses a Samsung panel (hmm - most Panasonics of the day used Hitachi-Panasonic IPS Alpha panels, so I'm guessing this was a budget model) which is prone to suffer from a tab bond failure, the top left bonding on the panel fails causing a blurry/slow or dark-tinted image.
Hmm that sounds bad but would make sense, i can't reach these tab-connections to prove this so yeah.. let's hope it's 'just' the tcon board.
I will order a new T-CON Board at the end of the month and tell you the result then..
Greetings and thanks again
- morxw