Hello.

I'm the owner of an old NEC 3D monitor (I bought it around 1988 or so),
and it was working fine till I stopped using it for a few months and
switched it back on yesterday... Suddenly, the image collapsed vertically:
the bottom half is still readible and apparently not too distorted, but
the top half lines have collapsed to a mere 3cm high band, in which the
text even appears inverted (upside down) for the top lines.

I opened the monitor and checked for the trimmers (dirt may sometime be
responsible for false contacts) and for any defect that would be visible
(exploded or leaking capacitors, burnt resistors, diodes or transistors),
but I found nothing wrong. Before I spend more time investigating, did
anyone else already encounter such a problem and/or could give advice as
to where to direct my investigations ?

This monitor is the only one I got that is capable of displaying old
computers images (15Khz Hsync), and I do need it...

Many thanks in advance !

Thierry Godefroy.

On 19 Feb, 18:18, anonymous wrote:

Hello.

I'm the owner of an old NEC 3D monitor (I bought it around 1988 or so),
and it was working fine till I stopped using it for a few months and
switched it back on yesterday... Suddenly, the image collapsed vertically:
the bottom half is still readible and apparently not too distorted, but
the top half lines have collapsed to a mere 3cm high band, in which the
text even appears inverted (upside down) for the top lines.

I opened the monitor and checked for the trimmers (dirt may sometime be
responsible for false contacts) and for any defect that would be visible
(exploded or leaking capacitors, burnt resistors, diodes or transistors),
but I found nothing wrong. Before I spend more time investigating, did
anyone else already encounter such a problem and/or could give advice as
to where to direct my investigations ?

I'd start by getting a circuit diagram, then you can check varous
voltage points in the horiz scan section.


This monitor is the only one I got that is capable of displaying old
computers images (15Khz Hsync), and I do need it...

none of your newer ones will do 15kHz horiz? I'm surprised, most bog
standard 17" ones will do that.


NT

On Mon, 19 Feb 2007 19:18:22 +0100, anonymous put
finger to keyboard and composed:

Hello.

I'm the owner of an old NEC 3D monitor (I bought it around 1988 or so),
and it was working fine till I stopped using it for a few months and
switched it back on yesterday... Suddenly, the image collapsed vertically:
the bottom half is still readible and apparently not too distorted, but
the top half lines have collapsed to a mere 3cm high band, in which the
text even appears inverted (upside down) for the top lines.

I opened the monitor and checked for the trimmers (dirt may sometime be
responsible for false contacts) and for any defect that would be visible
(exploded or leaking capacitors, burnt resistors, diodes or transistors),
but I found nothing wrong. Before I spend more time investigating, did
anyone else already encounter such a problem and/or could give advice as
to where to direct my investigations ?

This monitor is the only one I got that is capable of displaying old
computers images (15Khz Hsync), and I do need it...

Many thanks in advance !

Thierry Godefroy.

Look for dry electrolytic capacitors in the vertical section.
Otherwise, if your chassis uses discrete transistors for the vertical
amp, then check those. The worst case scenario is a bad yoke.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc Zabkar writes:

On Mon, 19 Feb 2007 19:18:22 +0100, anonymous put
finger to keyboard and composed:

Hello.

I'm the owner of an old NEC 3D monitor (I bought it around 1988 or so),
and it was working fine till I stopped using it for a few months and
switched it back on yesterday... Suddenly, the image collapsed vertically:
the bottom half is still readible and apparently not too distorted, but
the top half lines have collapsed to a mere 3cm high band, in which the
text even appears inverted (upside down) for the top lines.

I opened the monitor and checked for the trimmers (dirt may sometime be
responsible for false contacts) and for any defect that would be visible
(exploded or leaking capacitors, burnt resistors, diodes or transistors),
but I found nothing wrong. Before I spend more time investigating, did
anyone else already encounter such a problem and/or could give advice as
to where to direct my investigations ?

This monitor is the only one I got that is capable of displaying old
computers images (15Khz Hsync), and I do need it...

Many thanks in advance !

Thierry Godefroy.

Look for dry electrolytic capacitors in the vertical section.
Otherwise, if your chassis uses discrete transistors for the vertical
amp, then check those. The worst case scenario is a bad yoke.

Or if you want a working NEC 3D I'm about to toss.....

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

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

none of your newer ones will do 15kHz horiz? I'm surprised, most bog
standard 17" ones will do that.



Not any I've seen that were made in the last decade or more. The last
VGA monitor I had that was capable of 15 KHz was a Sony CPD-1302 made
circa 1988.

anonymous ha escrito:
Hello.

I'm the owner of an old NEC 3D monitor (I bought it around 1988 or so),
and it was working fine till I stopped using it for a few months and
switched it back on yesterday... Suddenly, the image collapsed vertically:
the bottom half is still readible and apparently not too distorted, but
the top half lines have collapsed to a mere 3cm high band, in which the
text even appears inverted (upside down) for the top lines.


classic symptoms of bad caps in the vertical section. just replace
them

-B.

On 20 Feb, 08:03, James Sweet wrote:

none of your newer ones will do 15kHz horiz? I'm surprised, most bog
standard 17" ones will do that.

Not any I've seen that were made in the last decade or more. The last
VGA monitor I had that was capable of 15 KHz was a Sony CPD-1302 made
circa 1988.

I stand corrected, had forgotten to take interlacing into account. Can
the OP not use a TV?


NT

On Tue, 20 Feb 2007 07:54:31 +1100, Franc Zabkar wrote:

On Mon, 19 Feb 2007 19:18:22 +0100, anonymous put
finger to keyboard and composed:

Hello.

I'm the owner of an old NEC 3D monitor (I bought it around 1988 or so),
and it was working fine till I stopped using it for a few months and
switched it back on yesterday... Suddenly, the image collapsed vertically:
the bottom half is still readible and apparently not too distorted, but
the top half lines have collapsed to a mere 3cm high band, in which the
text even appears inverted (upside down) for the top lines.

I opened the monitor and checked for the trimmers (dirt may sometime be
responsible for false contacts) and for any defect that would be visible
(exploded or leaking capacitors, burnt resistors, diodes or transistors),
but I found nothing wrong. Before I spend more time investigating, did
anyone else already encounter such a problem and/or could give advice as
to where to direct my investigations ?

This monitor is the only one I got that is capable of displaying old
computers images (15Khz Hsync), and I do need it...

Many thanks in advance !

Thierry Godefroy.

Look for dry electrolytic capacitors in the vertical section.
Otherwise, if your chassis uses discrete transistors for the vertical
amp, then check those. The worst case scenario is a bad yoke.

- Franc Zabkar

Thank you (and everyone else) for your advice. I indeed think it has
something to do with a bad capacitor or transistor... Alas, without a
schematic, it's like searching with blindfolded eyes. I therefore wrote to
NEC, and I hope they will provide me with a schematic...

Regards,

Thierry Godefroy.

On Thu, 22 Feb 2007 20:16:37 +0100, anonymous put
finger to keyboard and composed:

Thank you (and everyone else) for your advice. I indeed think it has
something to do with a bad capacitor or transistor... Alas, without a
schematic, it's like searching with blindfolded eyes.

I don't know if it's the same beast, but a service manual with
circuits for an NEC Multisync 3D (model JC-1404) is available for free
download (in four parts) from he

http://www.eserviceinfo.com/download.php?fileid=7872

If your monitor has an LA7835 vertical output chip, then change the
capacitors nearby.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

On Fri, 23 Feb 2007 16:39:56 +1100, Franc Zabkar wrote:

On Thu, 22 Feb 2007 20:16:37 +0100, anonymous put
finger to keyboard and composed:

Thank you (and everyone else) for your advice. I indeed think it has
something to do with a bad capacitor or transistor... Alas, without a
schematic, it's like searching with blindfolded eyes.

I don't know if it's the same beast, but a service manual with
circuits for an NEC Multisync 3D (model JC-1404) is available for free
download (in four parts) from he

http://www.eserviceinfo.com/download.php?fileid=7872

If your monitor has an LA7835 vertical output chip, then change the
capacitors nearby.

- Franc Zabkar

WOW ! Cool ! Many thanks: that's excatly what I was searching for ! :-)

Best regards,

Thierry Godefroy.

was this the one that the electrolytic capacitors leak and hurt traces
on the multi layer main board...

if you see physical, electrolyte leakage on the board, it is, and you
must be careful because the traces are very small ... usually require
jumping some with wire...i tried to get one going once like this and i
gave up ... the degree of damage can vary alot and mine was a pretty bad one