Previous in Forum: BSDV and PSDV   Next in Forum: Recommend Books for Instr. Engineering Calculations
Close
Close
Close
11 comments
Active Contributor

Join Date: Mar 2011
Posts: 11

Damage LCD-DOT Matrix Display

03/08/2011 9:48 PM

what can cause an lcd-dot matrix display to have dead pixels?

this is my situation, my clients ABB Brand Electromagnetic Flowmeter

FXE4000, has been installed almost 2 years in the field, the problem now is its lcd display is unreadable please see the attached picture.

ive been thinking if its the sunlight or the heat from sunlight can cause this problem, my client is skeptical because replacing this lcd unit cost higher than their budget is allocated, and they want to find out what cause this problem... help me guys...

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
4
Guru
Engineering Fields - Optical Engineering - Member Engineering Fields - Engineering Physics - Member Engineering Fields - Systems Engineering - Member

Join Date: Apr 2010
Location: Trantor
Posts: 5363
Good Answers: 646
#1

Re: Damage LCD-DOT Matrix Display

03/08/2011 10:23 PM

The mostly likely cause of failure is the bond between the LCD and the connector at the edge of the LCD, connecting it to the driver board. The two most common causes of this failure are heat and humidity. Sunlight can cause a build up of heat within the unit causing this bond to fail. Likewise humidity can cause rapid oxidization of the conductive pads at this LCD-connector bond.

(You could verify this with a new LCD; see if works OK with the driver board. If not the problem would lie elsewhere.)

Depending on the connection method, it may or may not be repairable. Talk to your LCD supplier and see if they can fix it. They need to do a failure analysis and see if there is a method of protecting the LCD to prevent this from happening in the future. You can also google 'LCD repair' and perhaps find a company that can fix the LCD cheap.

__________________
Whiskey, women -- and astrophysics. Because sometimes a problem can't be solved with just whiskey and women.
Register to Reply Good Answer (Score 4)
Active Contributor

Join Date: Mar 2011
Posts: 11
#2
In reply to #1

Re: Damage LCD-DOT Matrix Display

03/09/2011 12:09 AM

thanks for your reply..

Register to Reply
Guru
Engineering Fields - Instrumentation Engineering - New Member

Join Date: Dec 2009
Location: San Antonio, TX USA
Posts: 844
Good Answers: 28
#3

Re: Damage LCD-DOT Matrix Display

03/09/2011 8:40 AM

The condition of that conduit connection makes me wonder about water intrusion.

__________________
"Do not worry about your difficulties in Mathematics. I can assure you mine are still greater". - Albert Einstein
Register to Reply
Associate

Join Date: May 2010
Location: Islamabad, Pakistan.
Posts: 40
Good Answers: 1
#4
In reply to #3

Re: Damage LCD-DOT Matrix Display

03/10/2011 12:04 AM

Take out the lcd from four white hooks at top, left and right as shown in your picture.Lcd must be flipped downward. Underneath resolder all the pads with fresh solder.

Have fun.

__________________
Join Date: 24/10/2007
Register to Reply
Associate

Join Date: May 2010
Location: Islamabad, Pakistan.
Posts: 40
Good Answers: 1
#5
In reply to #4

Re: Damage LCD-DOT Matrix Display

03/10/2011 2:09 AM

If above do not work, then try this.

Heat the glue holding the LCD's ribbon cable to PCB with a hot air gun (you can also use solder iron for heating ,but use a card board on the ribbon, so that it will not melt down ) and using a flat screw driver to re-attach segments of the ribbon cable to the PCB.

Have fun.

__________________
Join Date: 24/10/2007
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#6

Re: Damage LCD-DOT Matrix Display

03/10/2011 4:58 AM

UV is really bad for LCD displays.......

Once its repaired, fit it with a hinged flap to keep it covered when not being looked at, that does not a) let UV through and b) is not itself UV sensitive.......

Problem solved.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
2
Power-User

Join Date: Jan 2008
Location: Allen, TX
Posts: 107
Good Answers: 2
#7

Re: Damage LCD-DOT Matrix Display

03/10/2011 8:16 AM

Dred,

Could this unit have frozen? I don't know about the current generation of LCDs but earlier ones were subject to damage when temperatures fell too low (I lost a good calculator that way). Maybe you could check the manufacturer's data sheet and see if the unit has a temperature-tolerance range.

Logan

Register to Reply Good Answer (Score 2)
Active Contributor

Join Date: Mar 2011
Posts: 11
#11
In reply to #7

Re: Damage LCD-DOT Matrix Display

03/11/2011 12:55 AM

i dont think this unit could have been frozen, since here in our country philippines, the weather is somewhat always warm, and in rainy season the temperature would only be around 25 deg. C

i looked at the operating condition on the manual and it says ambient to 60 deg. C, and the temperature if its summer season here in our country would only reach 36 deg. C at most, but maybe my guess is that at the unit would only around 40 deg. C or my assumption

Register to Reply
Guru

Join Date: Apr 2008
Location: Chicago
Posts: 3989
Good Answers: 144
#8

Re: Damage LCD-DOT Matrix Display

03/10/2011 10:54 AM

I see little white tabs holding the LCD in place.

I would try to pop off the LCD and see if there was a zebra noodle (not the real name) stuck to the backside? I'll bet there is..

It would be positioned at the top or bottom and run the length of the display.

At a glance it will look like a gray plastic box shaped strip, but it's actually flexible. The strip is made up of a hundreds of tiny layers of conductive and non conductive materials, and it's only job is to be the conductor between the flat surface electrodes on the PCB and the ones on the back of the glass LCD display.

The connection between the LCD and the PCB has many signal paths that run through this noodle, but it relies on pressure to hold it in place, and luck to ensure it's continued operation.

To test if this is the case apply a little finger pressure land rub it back and forth across the top and bottom of the LCD. You might see that all or most of the display temporarily returns.

This is because you are creating a tighter bond and better connection to the possibly oxidized pads on the noodle.

If the display is hardwired, this won't be the case, but 90% of the time I can diagnose and fix and LCD display issue without so much as a little clean up and a tiny screwdriver.

It may or may not be recommended, but I've used whatever is available to give the PCB a little wipe down with a Q-tip and some electronics cleaner... or the edge of my shirt and some spit.

If you pop the noodle off, just stick it back onto conductors printed onto the glass on the back of the LCD. The hundreds of layers make positioning this strip easy.

More often than not just pulling the strip off and putting the display back a couple times will rough up the surface enough to restore the LCD.

In some cases the pressure on the LCD / noodle / PCB sandwich is too little.

putting a mini shim less than the the thickness of a credit card under the white tabs could alleviate this. (cut them from a water bottle)

good luck!

__________________
High Tolerance is Beautiful
Register to Reply Score 1 for Good Answer
Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
Posts: 5426
Good Answers: 293
#9
In reply to #8

Re: Damage LCD-DOT Matrix Display

03/10/2011 1:02 PM
__________________
We are alone in the universe, or, we are not. Either way it's incredible... Adapted from R. Buckminster Fuller/Arthur C. Clarke
Register to Reply
Active Contributor

Join Date: Mar 2011
Posts: 11
#10

Re: Damage LCD-DOT Matrix Display

03/11/2011 12:47 AM

as of now, i haven't done anything yet on the lcd, since im still contacting the manufacturer for any possible reason from their side of what have caused this and any parts replacement if possible, manufacturers local representative of that instrument already told us that replacement would be the only solution, but the cost would be so high since the replacement is the front board module where the lcd is attached.

Register to Reply
Register to Reply 11 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

Andy Germany (1); dred (3); JE in Chicago (1); logan (1); Randall (1); RDGRNR (1); Usbport (1); wahaj87 (2)

Previous in Forum: BSDV and PSDV   Next in Forum: Recommend Books for Instr. Engineering Calculations

Advertisement