[MELB] HP A2094A monitor (Sony GDM-1934) for anyone interested

[Dave]

G'day folks, if repair techs, etc, are interested in the above 20"
monitor they can have it as long as you can pick it up, (I'm on Mt
Dandenong).

I think it's a GDM-1934 variant, (after doing a Google search), it's
fixed frequency, 1280*1024 72Hz 78.125kHz 5*BNC,(R,G,B,HD,VD), inputs &
outputs.

It might have a problem, I couldn't get it to sync to my PC output when
set to 1280*1024 72Hz, but the Trinitron tube seems to be fine - at
least what I could see of it as it was trying to sync.

Anyone interested in doing a swap for approx. 4 high voltage film
capacitors?

Otherwise I'll start pulling it apart to see if I can get the parts I
need for another Trinitron monitor - or if someone can send me the parts
list for it from the Service Manual, I can see if it has the parts I
need without pulling it apart.

Thanks,
Dave

 

[Clifford Heath]

It might have a problem, I couldn't get it to sync to my PC output when
set to 1280*1024 72Hz, but the Trinitron tube seems to be fine - at
least what I could see of it as it was trying to sync.

How did you inject the sync? These monitors mostly take sync on green.
I've had success operating workstation monitors from a VGA card under
Linux (where I have complete control over scan settings) by hooking
the Vsync and Hsync to the Green via a pair of 220 Ohm resisters.
The video level is a little low, so you can't quite get full brightness,
but that doesn't bother me, in fact I'm looking at an HP98752A
(rebadged Sony) right now.

Clifford Heath.

 

[Dave]

How did you inject the sync? These monitors mostly take sync on green.
I've had success operating workstation monitors from a VGA card under
Linux (where I have complete control over scan settings) by hooking
the Vsync and Hsync to the Green via a pair of 220 Ohm resisters.
The video level is a little low, so you can't quite get full brightness,
but that doesn't bother me, in fact I'm looking at an HP98752A
(rebadged Sony) right now.

I thought of that and have a small cct diagram for combining H & Vsync
to give sync on green but couldn't be bothered trying it - was a bit
more than a pair of resistors
I just used the VGA->BNC cable, guess I could try puting the resistors
on the back of the BNC connectors just so I can see if the monitor does
indeed work properly but in the end I'd rather fix my IBM P70 multiscan,
(Sony 17SE2T - reduced width problem), than be stuck with just one
resolution/scan rate - also the P70 isn't quite so cumbersome!

Suddenly got into this fix all the gizmos mode:

NEC N9570A - requires idler assembly
NEC 3D - replace all the electros (vertical foldover)
IBM P70 - reduced width (try to replace HV caps - if I can find
them)
Sony SLC40ES - tape take up not quite working fast enough
Couple of TEAC VHS recorders found during hard rubbish that require a
bit of mechanical tweaking but otherwise record and play fine - the
things people throw out. Still using a perfectly good microwave that
someone threw out - couldn't have matched their new kitchen!

The fun never stops

BTW, if anyone can help, the 17SE2T manual lists some caps as:

C432 1-113-714-11 FILM 2000pF 3% 2KV

Anyone know where I can get caps of that spec, (besides genuine Sony
parts), bearing in mind I only want small quantities, (ie. 1 or 2 of a
value)?

Also, when they say 'FILM', exactly what construction are they talking
about?
Looking at them I'd say polypropylene, which are suitable for the H
output section.

Dave

 

[Clifford Heath]

I thought of that and have a small cct diagram for combining H & Vsync
to give sync on green but couldn't be bothered trying it - was a bit
more than a pair of resistors

Wouldn't mind seeing that - got a scanner or an electronic version?

I run Linux where fixed scan isn't a problem, but even on Windoze
if you use a dual-screen adapter a fixed-scan monitor works well as
a 2nd screen.

I just used the VGA->BNC cable, guess I could try puting the resistors
on the back of the BNC connectors

More-or-less what I did. Use -ve sync for both H and V.

BTW, if anyone can help, the 17SE2T manual lists some caps as:
C432 1-113-714-11 FILM 2000pF 3% 2KV

I bought a pack of 3Kv caps from Oatley a while back with the thought
of building a Cockroft-Walton voltage multiplier for an ion generator.
Never bought the diodes though. They're marked "B 152K CM04", so I
guess that's 1500pF, pretty close to what you want. You're welcome to
a couple if you pick them up (email heaths08 at optusnet dot com for
location, Melbourne ES). Or I could drop a few in an envelope.

Also, when they say 'FILM', exactly what construction are they talking
about?

Dunno, but not many types are made for that V rating, and I guess that's
what matters.

Clifford Heath.

 

[Dave]

Wouldn't mind seeing that - got a scanner or an electronic version?

GIF file, I'll send it to the address you've given below.

I run Linux where fixed scan isn't a problem, but even on Windoze
if you use a dual-screen adapter a fixed-scan monitor works well as
a 2nd screen.

That's what I'm testing it with, (ATI Radeon 9600 as the 2nd monitor).
Under the display properties, (as I just discovered), I can set max
vertical freq. (72Hz), max. res. (1280*1024), the HSync/VSync polarities
and also composite sync. However, none of these provide compatibility
with sync-on-green monitors, (according to ATI WWW site).

But, (I obviously wasn't awake during my last reply), it shouldn't be
needed since the monitor has inputs for HSync and VSync and I have the
correct cable VGA->5*BNC. Sync-on-green would only be needed if I only
had basic RGB, (3*BNC), inputs.

Indeed, there's a website telling you how to mod a Sony GDM-1960/61 just
by adding 2 more BNC sockets for HSync/VSync and a couple of resistors -
apparently there are places on the input board just waiting for these
components. It also has a link to another sync-on-green adapter.

In case you're interested:
http://vmlinux.org/jocke/mirror/www.geocities.com/SiliconValley/Foothills/4467/fixedsync.html

BING! Just realised, that page actually mentions a HP98752A, sound
familiar success story done WITHOUT a sync-on-green adapter with
Win95 - you may be able to set the monitor specs in Linux up the same.

However, no matter what combination of sync I try, the monitor won't
oblige - I can almost get it to do it if I play around with the Low
H.Freq adjust on the main PCB, (they even supply a service tool in the
monitor!).

I've created space on the HD and will install Linux, (been a while since
I used it last), and see if I can get it to work with that.

I bought a pack of 3Kv caps from Oatley a while back with the thought
of building a Cockroft-Walton voltage multiplier for an ion generator.
Never bought the diodes though. They're marked "B 152K CM04", so I
guess that's 1500pF, pretty close to what you want. You're welcome to
a couple if you pick them up (email heaths08 at optusnet dot com for
location, Melbourne ES). Or I could drop a few in an envelope.

Thanks for the offer, I'll see how I go, got to make a list of
everything I need for these repair jobs then see what I can get on my
next journey "down from the mountain"

Dave

 

[Craig Hart]

How did you inject the sync?

note original post: *5* BNC inputs - R,G,B,*VS*,*HS*