NEC multisync LCD 1810

[Dave Walker]

Hi,
I now have 3 of these 18 inch LCD flat screens, each one has failed with the
same fault, after approx 3 years use.
The monitor turns on, displays a picture for approx half a second then goes
blank, power light remains on. If the input switch (BNC / D-SUB ) is cycled
then the picture will appear again, briefly, as will cycling the power too.
The power lamp remains on after the picture has disappeared. I have tried
exchanging the external PSU with a good one to no effect.
If anyone has experience of these monitors, or similar fault, please help!

 

[John]

Sounds like the florescent tube inverter or the tube itself may be at fault.
First test any electrolytic capacitors on the inverter board.
Good luck John.

 

[JW]

On Wed, 5 May 2004 21:45:05 +0100 "Dave Walker" <spam@btinternet.com>
wrote in Message id: <c7bjp4$23grj$1@ID-225925.news.uni-berlin.de>:

Hi,
I now have 3 of these 18 inch LCD flat screens, each one has failed with the
same fault, after approx 3 years use.
The monitor turns on, displays a picture for approx half a second then goes
blank, power light remains on. If the input switch (BNC / D-SUB ) is cycled
then the picture will appear again, briefly, as will cycling the power too.
The power lamp remains on after the picture has disappeared. I have tried
exchanging the external PSU with a good one to no effect.
If anyone has experience of these monitors, or similar fault, please help!

I fixed one of these with the exact same fault several weeks ago - you
have one or more blown picofuses on the inverter board - IIRC there are
four of them F2 F3 F4 and F5 - use a ohm meter to find and replace the
open ones. I suspect that they are slightly under rated at 1.25A, and open
pretty easily. I replaced 2 of them with 1.5A devices and it's worked fine
ever since.

Good luck! BTW, if you ever need a power supply look no further than here:
http://www.mpja.com/directview.asp?product=15349+PS
15 bucks! There's a guy who sells them on Ebay for the outrageous price of
$80.

 

[Dave Walker]

I fixed one of these with the exact same fault several weeks ago - you
have one or more blown picofuses on the inverter board - IIRC there are
four of them F2 F3 F4 and F5 - use a ohm meter to find and replace the
open ones. I suspect that they are slightly under rated at 1.25A, and open
pretty easily. I replaced 2 of them with 1.5A devices and it's worked fine
ever since.

Thankyou so much.
I'd looked around inside but I would never have spotted those *tiny* fuses.
I tested one of the boards, and two were indeed o/c. Even my weller station
is not good enough to replace them, but in true Heath Robinson fashion I
extended the connections out with wire to two normal glass 1.6A fast fuses.
That display seems OK now, it ran for 20 minutes with no problem. Would you
say it was a new lease of life or short term? Is it the ageing of the tubes
that causes the failure?
I'll get round to checking the other two displays soon, but once again,
thankyou for your help.

 

[JW]

On Thu, 6 May 2004 23:23:23 +0100 "Dave Walker" <spam@btinternet.com>
wrote in Message id: <2fvs96F30lb0U1@uni-berlin.de>:

I fixed one of these with the exact same fault several weeks ago - you
have one or more blown picofuses on the inverter board - IIRC there are
four of them F2 F3 F4 and F5 - use a ohm meter to find and replace the
open ones. I suspect that they are slightly under rated at 1.25A, and open
pretty easily. I replaced 2 of them with 1.5A devices and it's worked fine
ever since.


Thankyou so much.
I'd looked around inside but I would never have spotted those *tiny* fuses.
I tested one of the boards, and two were indeed o/c. Even my weller station
is not good enough to replace them, but in true Heath Robinson fashion I
extended the connections out with wire to two normal glass 1.6A fast fuses.
That display seems OK now, it ran for 20 minutes with no problem. Would you
say it was a new lease of life or short term? Is it the ageing of the tubes
that causes the failure?

I can't say for sure in your case, but mine has worked fine for several
weeks now. Like I said, I think that the fuses are a little bit
under-rated which could have caused the original failure. I had a second
one with the same exact failure, but after replacing the blown fuses,
while the screen stayed lit, there are lines through the display, so I'm
keeping this one for spare parts.

I'll get round to checking the other two displays soon, but once again,
thankyou for your help.

You're very welcome - I'll bet good money that you'll find the same exact
fault in the other two; I'm guessing that part of the inverter circuit
somehow senses the non-functioning parts of the inverter, and shuts down
as a sort of fail-safe protection. Let me know how you make out with the
other two, I'm quite curious...

 

[Dave Walker]

You're very welcome - I'll bet good money that you'll find the same exact
fault in the other two; I'm guessing that part of the inverter circuit
somehow senses the non-functioning parts of the inverter, and shuts down
as a sort of fail-safe protection. Let me know how you make out with the
other two, I'm quite curious...

Number 2 - once again two fuses, F4 F5 blown. Replaced them but this time it
just blinks on / off, continuous cycling, both picture and on / off LED.
Took apart for another look, F2 blown now. Replaced that, no change.
Re-checked, all fuses still OK.
One more to look at, will let you know on that one later.

 

[JW]

On Fri, 7 May 2004 22:51:43 +0100 "Dave Walker" <spam@btinternet.com>
wrote in Message id: <2g2eorF3n5hiU1@uni-berlin.de>:

You're very welcome - I'll bet good money that you'll find the same exact
fault in the other two; I'm guessing that part of the inverter circuit
somehow senses the non-functioning parts of the inverter, and shuts down
as a sort of fail-safe protection. Let me know how you make out with the
other two, I'm quite curious...


Number 2 - once again two fuses, F4 F5 blown. Replaced them but this time it
just blinks on / off, continuous cycling, both picture and on / off LED.
Took apart for another look, F2 blown now. Replaced that, no change.
Re-checked, all fuses still OK.

Interesting.

One more to look at, will let you know on that one later.

Excellent. Say, do any of your displays have a mechanical problem? Mine
has a problem where the tilt mechanism does not hold the monitor where
it's positioned. Instead, the LCD display slowly tilts downward till it's
at it's lowest point. There's a compression type mechanism that seems to
work using a spring type bushing which causes friction on a steel plate -
obviously there's not enough friction. However, there is no way to adjust
the pressure that I can see, and the thing seems to be permanently pressed
together. The mechanism on my spare is missing. Have you seen this
problem?

 

[Dave Walker]

Excellent. Say, do any of your displays have a mechanical problem? Mine
has a problem where the tilt mechanism does not hold the monitor where
it's positioned. Instead, the LCD display slowly tilts downward till it's
at it's lowest point. There's a compression type mechanism that seems to
work using a spring type bushing which causes friction on a steel plate -
obviously there's not enough friction. However, there is no way to adjust
the pressure that I can see, and the thing seems to be permanently pressed
together. The mechanism on my spare is missing. Have you seen this
problem?

Final display - once again failed fuses, but the board only ran for minutes
before strange things occurred, picture appears to smear and collapse. Not
believing it to be the board at fault I put in a previous display and the
same problem. Anyway, one out of three is still a success.
I only have two stands, and both work fine. However, I don't think either of
them ever saw much service.

 

[rtanderson]

The inverter board that runs the floursecent board, I have seen blows
those pico fuses too and is usually caused by shorted surface mount
transistors, so i recommend checking those too nearby those fuses.

as far as the fuses i have taken a glass fuse of the same current
rating ..broken the glass and just tack soldered the wire over the
body of the fuse...being it is the same current rating to open it will
still protect the circuit.. (heeheehee)

only thing I hate about these displays is if you leave an image on
them for extended time the tend to ghost


"Dave Walker" <spam@btinternet.com> wrote in message news:<2gidoeF3b254U1@uni-berlin.de>...

Excellent. Say, do any of your displays have a mechanical problem? Mine
has a problem where the tilt mechanism does not hold the monitor where
it's positioned. Instead, the LCD display slowly tilts downward till it's
at it's lowest point. There's a compression type mechanism that seems to
work using a spring type bushing which causes friction on a steel plate -
obviously there's not enough friction. However, there is no way to adjust
the pressure that I can see, and the thing seems to be permanently pressed
together. The mechanism on my spare is missing. Have you seen this
problem?


Final display - once again failed fuses, but the board only ran for minutes
before strange things occurred, picture appears to smear and collapse. Not
believing it to be the board at fault I put in a previous display and the
same problem. Anyway, one out of three is still a success.
I only have two stands, and both work fine. However, I don't think either of
them ever saw much service.

 

[AndyF]

I have just bought an NEC 1810 which has a fault. It displays green
vertical lines across the whole screen at a regular 1/4 inch spacing.
The lines are there at power up and when fed from with a PC signal,
although the picture behind the lines looks fine! Any ideas what's
causing the lines?

Andy

 

[Michael]

In article <f27f3859.0405281311.5b2fe28e@posting.google.com>,
andyfarthing@onetel.net.uk (AndyF) wrote:

I have just bought an NEC 1810 which has a fault. It displays green
vertical lines across the whole screen at a regular 1/4 inch spacing.
The lines are there at power up and when fed from with a PC signal,
although the picture behind the lines looks fine! Any ideas what's
causing the lines?

Andy

Your LCD is bad. Specifically, the driver ICs that address each row and
column have failed, or the bond between the conductive glass and the
metal conductors, at the edge of the screen, has failed. Given that you
have lines recurring at regular intervals, as opposed to one or two
random ones, I'd guess it's the ICs. There's nothing you can do to fix
that, I'm afraid.

I've seen this on many laptop LCDs and a few of the type used in pocket
TVs and Video Walkmans. It was a very common failure in the earlier days
of LCDs, but it still happens.

Sincerely,
Michael

 

[hrijswijk]

Hi,

Have you found the solution for the monitor which "ran for minutes
before strange things occurred, picture appears to smear and collapse".

I've a monitor NEC LCD1810X whit the same problem.

Harm






"Dave Walker" <spam@btinternet.com> wrote in message news:<2gidoeF3b254U1@uni-berlin.de>...

Excellent. Say, do any of your displays have a mechanical problem? Mine
has a problem where the tilt mechanism does not hold the monitor where
it's positioned. Instead, the LCD display slowly tilts downward till it's
at it's lowest point. There's a compression type mechanism that seems to
work using a spring type bushing which causes friction on a steel plate -
obviously there's not enough friction. However, there is no way to adjust
the pressure that I can see, and the thing seems to be permanently pressed
together. The mechanism on my spare is missing. Have you seen this
problem?


Final display - once again failed fuses, but the board only ran for minutes
before strange things occurred, picture appears to smear and collapse. Not
believing it to be the board at fault I put in a previous display and the
same problem. Anyway, one out of three is still a success.
I only have two stands, and both work fine. However, I don't think either of
them ever saw much service.

 

[Dave Walker]

"hrijswijk" <harm.j.rijswijk@raketnet.nl> wrote in message
news:f89abf0b.0405301042.6f6813de@posting.google.com...

Hi,

Have you found the solution for the monitor which "ran for minutes
before strange things occurred, picture appears to smear and collapse".

I've a monitor NEC LCD1810X whit the same problem.

Harm

Afraid not - I substituted the LCD panel with all the attached boards, no
change - so it looks like again the inverter board.