Author Topic: Eizo LCD monitor S2431W repair - horizontal colored lines  (Read 8636 times)

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Offline UlToPri

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Eizo LCD monitor S2431W repair - horizontal colored lines
« on: July 13, 2014, 06:07:36 pm »
Hi!

I try to repair a Eizo LCD monitor S2431W.

It has a couple of horizontal colored lines which are completly
independent of the inputs. Even with no input cable connected the
lines are visible.

My guess is a power supply error (which is a simple one voltage out
supply) because:
- The error came slowly. It had started with three lines in a row and
  after a couple of months there were round about 10 lines.
- Nowadays in the moment of powering on the monitor there are lines
  all about the screen and a second later most of them disapeared.

I checked visually the caps in the buildin power supply. They are all
good brand Nichicon and Nippon Chemi-Con and seem to be OK.

I don't see a defect on the other boards (inverter, main and LCD)
ether.

I measured the out-voltage of the power supply. It is 18.1 V. The
power supply is always on (soft-power switch). In the power on moment
the voltage drops to 15 V (measured with a multimeter min-function).

I try to get a oscilloscope next week to visualize the out-voltage
better.

The output filter cap has a voltage rating of 25 V. So 18 V may be OK
or it was originally 19 V or 20 V.

My questions:
1. Does someone know this type of error and the solution?
2. Does someone know which voltage the power supply should have on the
   secondary side?

My next steps (depends on your answers, too):
- drive the monitor with a bench power supply (this needs a bit of
  hacking because they used the power supply board to get three
  control lines from the main to the inverter board)
- get an image of the supply voltage
- change the caps in the power supply

Thanks for your help!

Tom

 

Offline UlToPri

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #1 on: July 20, 2014, 09:43:34 am »
Hi again - an update!

I did a new detail picture of the error - less dusty and more in focus.
I don't think my tiny camera can do better than this.

I got the scope and did some pictures - see attachments.
* The power on voltage dip of 2 V seems to be the backlight.
* The trigger mark on the right side of the detail picture is 16 V.

The ripple voltage of 300 mVpp may be OK. Maybe the power supply isn't
faulty att all? Is there no one who knows which voltage out the power
supply should have?

Thanks!
Tom

 

Offline mij59

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #2 on: July 20, 2014, 11:02:50 am »
Hi,

I don't think it's the power supply.

Looks more like a driver problem, or even worst a problem in the lcd screen .

If you feed in a signal, its displayed correctly except for the colored lines ?
Does the pattern in the colored lines change ?
Please post a photo of the pcb.
   
 

Offline UlToPri

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #3 on: July 20, 2014, 05:48:13 pm »
Quote from: mij59 on Today at 01:02:50 PM
Hi,

I don't think it's the power supply.

I don't think this either - anymore.

Looks more like a driver problem, or even worst a problem in the lcd screen .

Yes, it seems so.

If you feed in a signal, its displayed correctly except for the colored lines ?
Does the pattern in the colored lines change ?

Yes the lines are staying with or without a signal and it doesn't
matter if I feed the signal via DVI-D or VGA.
And yes the pattern are changing even with a still image as signal.

Please post a photo of the pcb.
 
Done. I attach an overall picture, a front of the power, the main
and the panel driver PCB.
The panel driver PCB
(which comes with the panel and is no Eizo part)
is sitting behind the power PCB and has extra shielding.
The panel is a Samsung LTM240M2-L01
.

I have done this today:
* Powered the Inverter and the Main PCB from a bench supply
* Increased slowly the voltage of the bench supply from 18 V to 21 V
* Used freezer spray on all ICs on the main and the panel driver PCB
* Flexed slightly the main and the panel driver PCB

--> no differences at all :-(

My conclusion:
The defect may sitting in the panel itself which does not seem to be
easy servicable. On the other hand I didn't think there are any defects
in the panel I can fix with my soldering station. It will be mainly
flex cabel with on cable mounted IC.

It seems to me the monitor is beyond repair. A new panel costs more an
halv a new monitor on ebay. It's a pitty.

Tom
 

Offline mij59

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #4 on: July 20, 2014, 06:23:14 pm »
Hi,

Yes not looking good.

You could disconnect an reconnect the flex cables form the main panel to the driver panel, and from the driver panel to the lcd screen.
No shure, but there may an other driver board on the top of the lcd screen witch interfaces to the lcd screen.
 

Offline max-bit

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #5 on: July 21, 2014, 05:47:17 am »
1. Dead CPU
2. Dead AD converter
3. Dead IC Line Driver  (on LCD)
Look for cold solder ...
But I do not think it was in for repair
 

Offline gashtaan

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #6 on: June 02, 2015, 06:05:59 am »
Hi, did you give up on this? I have same monitor and same problem - three lines shows up few days ago :-\

http://tinypic.com/r/1zlsvue/8
http://tinypic.com/r/24gk0lz/8
 

Offline Rasz

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #7 on: June 02, 2015, 09:18:02 am »
while monitor is on try pushing all the chips with your finger (after discharging yourself)
genesis makes shitty scalers, I would suspect that is the problem
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Offline gashtaan

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #8 on: June 02, 2015, 11:27:54 am »
I'll try it... why do you think it could help?
 

Offline Rasz

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #9 on: June 02, 2015, 10:40:19 pm »
I'll try it... why do you think it could help?

it wont help, but if there are any bad solder joints on big components this is how you will find them
personally i suspect big chip with GENESIS logo (scaler)

do the lines move when you change resolution of the source?
Who logs in to gdm? Not I, said the duck.
My fireplace is on fire, but in all the wrong places.
 

Offline gashtaan

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #10 on: June 03, 2015, 02:56:11 pm »
No, resolution change have no effect on it...

Some pixels of these artifacts are flashing, keeps switching on/off, most of them are fixed however.
 

Offline gashtaan

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #11 on: June 05, 2015, 04:57:36 pm »
It just started to show other artifacts, it's getting worse rapidly...
 

Offline Rasz

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #12 on: June 06, 2015, 02:46:04 am »
if its not bad joints on ram/main chip then you can try heating up scaler chip to ~200C for ~20-30 seconds with a hotair
it still might be tcon, so im not so hot recommending swapping controllers, on the other hand its whole $12 + figuring out the pinouts
V29 Universal LCD Controller Board TV Motherboard VGA/HDMI/AV/TV/USB Interface
http://www.banggood.com/Universal-LCD-TV-Controller-Board-VGAHDMIAVTVUSB-Interface-p-936100.html?p=L90908952558201412PO
Who logs in to gdm? Not I, said the duck.
My fireplace is on fire, but in all the wrong places.
 

Offline gashtaan

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #13 on: June 06, 2015, 04:19:07 pm »
I don't know if the scaler is problem... it's not affected by signal or its resolution. I've found the T-con board here: http://www.shopjimmy.com/samsung-lj94-00798y-t-con-board.htm - they notes that horizontal lines on the screen are virtually NEVER caused by bad T-Con board.

I've another question... I accidently blew up the fuse on Main PCB, but I don't know what type is it. It is labeled as F901 on PCB. Please, do you know what type it is or where to get service manual for this monitor to find it out?
 

Offline UlToPri

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #14 on: July 06, 2015, 07:58:06 pm »
Hi, did you give up on this? I have same monitor and same problem - three lines shows up few days ago :-\

Yes I did.

I tried a couple of things though.
* Cold spray on all the ICs
* Wiggleing all the connectors
* Disconnect och connect all connectors
* Took apart the panel itself

The error did not change because of this. It changed only with time so nowadays the whole display is filled with these lines.

To sum it up:
I bought a new monitor - this time not an EIZO.

Tom
 

Offline gashtaan

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Re: Eizo LCD monitor S2431W repair - horizontal colored lines
« Reply #15 on: July 06, 2015, 08:09:32 pm »
I just replaced TCon board few days ago, and monitor works as good as new now... didn't you try to do this? TCon board can be bought for few bucks, it's definitely worth a try.
 


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