LCD reassembly problems
 

Hi,

I have often replaced backlights in LCD's. Occasionally, like just now, I
get one which no matter what I try, I can't get all the pixels to reconnect.
It's the business of that squidgy rubber contact strip that connects between
the PCB and the LCD glass and is held in place by the metal cover of the
LCD, where you twist the lugs that protude through the PCB to secure it. I
always try and leave the LCD intact, but occasionally, as in this case, the
backlight will not come out without dismantling it.

I don't think I have damaged anything, and I have cleaned all the relevant
contacts and the strip with alcohol and switch cleaner but there are still 2
vertical bars unconnecting. Pressing really hard on the LCD housing will
not light them. Does anyone have any general hints and tips for these?

Cheers,

Gareth.

"Gareth Magennis" writes:

Hi,

I have often replaced backlights in LCD's. Occasionally, like just now, I
get one which no matter what I try, I can't get all the pixels to reconnect.
It's the business of that squidgy rubber contact strip that connects between
the PCB and the LCD glass and is held in place by the metal cover of the
LCD, where you twist the lugs that protude through the PCB to secure it. I
always try and leave the LCD intact, but occasionally, as in this case, the
backlight will not come out without dismantling it.

I don't think I have damaged anything, and I have cleaned all the relevant
contacts and the strip with alcohol and switch cleaner but there are still 2
vertical bars unconnecting. Pressing really hard on the LCD housing will
not light them. Does anyone have any general hints and tips for these?

Have you tried turning the "zebra stripe" rubber strips around to see if
the dead areas move?

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"Sam Goldwasser" wrote in message
...
"Gareth Magennis" writes:

Hi,

I have often replaced backlights in LCD's. Occasionally, like just now,
I
get one which no matter what I try, I can't get all the pixels to
reconnect.
It's the business of that squidgy rubber contact strip that connects
between
the PCB and the LCD glass and is held in place by the metal cover of the
LCD, where you twist the lugs that protude through the PCB to secure it.
I
always try and leave the LCD intact, but occasionally, as in this case,
the
backlight will not come out without dismantling it.

I don't think I have damaged anything, and I have cleaned all the
relevant
contacts and the strip with alcohol and switch cleaner but there are
still 2
vertical bars unconnecting. Pressing really hard on the LCD housing
will
not light them. Does anyone have any general hints and tips for these?

Have you tried turning the "zebra stripe" rubber strips around to see if
the dead areas move?

--- sam | Sci.Electronics.Repair FAQ Mirror:
http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ:
http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites:
http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the
excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above
is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.



The squidgy bar thing might need moving a minute ammount

Have you tried turning the "zebra stripe" rubber strips around to see if
the dead areas move?


Well, they are still firmly bonded to the LCD glass so I thought I would
leave them that way to ensure they were in the right place, but I'll try it.

Thanks.

Gareth.

As long as the rubber strip covers the contacts on the board and glass,
the actual position is irrelevant, you can take it off and completely flip
it over. There are hundreds (maybe) of conductors running vertically in the
rubber strip that are in parallel, but not touching each other, that make up
the circuit path between the pads on the PC board and the conductive pads on
the glass. I would recommend only cleaning the board with a pencil eraser,
adn wiping the dust away with a lint-free cloth, and not the rubber or
glass. Many cleaners will dissolve the (semi)conductive material on the
glass, and eat away part of the conductors (carbon?) in the silicone-rubber
piece, making the problem worse.


"Gareth Magennis" wrote in message
...
Have you tried turning the "zebra stripe" rubber strips around to see if
the dead areas move?


Well, they are still firmly bonded to the LCD glass so I thought I would
leave them that way to ensure they were in the right place, but I'll try
it.

Thanks.

Gareth.

"Jopki Jopa" wrote in message
.. .
Just got a dirt cheap thinkpad 770 with 1024x768 TFT display which has 3
black vertical bars as per attached picture. I checked the cable for
shorts,disconnects and the LCD doesn't show any signs of damage. Could
this symptom be a result of an LCD being dropped and contacts leading to
the glass shifted? I didn't dare to dismantle the LCD metal frame...
just removed the LCD, cable, inverter, put the thing back together -
same behaviour.
Any ideas appreciated.
Thanks, Jiri


Normally this is either the ribbon cables bonding the panel to the driver
board, or a fault in the driver chips on those ribbons, it's rarely fixable.
You might find a similar machine with a bad motherboard though and swap
parts.