I recently acquired (from the dumpster) several Sun Microsystems 20"
monitors, model GDM - 20D10, which appear to be Sony Trinitrons on the
inside. They are really nice when working properly, but were
manufactured in 1994 so probably aren't worth sinking $ into.

I'd like to get two of them running to upgrade the 17" pair I'm
currently using.

One worked reasonably well as-is, but was unusable due to severe CRT
burn-in. The others had symptoms ranging from collapsed display to
failure to power on at all.

I made inquiries about professional repair, but nobody was willing to
provide even a diagnostic estimate - they said the chassis is
unreasonably difficult to work on.

I decided to have a go myself, and experienced the difficulties first
hand - the internals are completely surrounded by multiple layers of
metal shielding, with circuit boards mounted to the inside of the
shields all over the place. It takes almost an hour of disassembly just
to check the power supply fuse, and close to another hour to dismount
boards and arrange them such that one can apply power and take
measurements with any degree of safety.

Without going into tedious detail, I've swapped parts around and now
have two working monitors with good CRTs. One is almost perfect, except
for a slight "shimmer" (not sure how else to describe it), while the
other is sharp but exhibits faint retrace lines and has the display
offset to the left about 1/2" further than can be corrected with the
remote control.

It seems to me the remaining problems are minor and could probably be
corrected via internal adjustments, but there are a *lot*, mostly
unlabeled, and I'm well aware that fiddling with them to see what effect
they have is not the recommended approach. Looks like these monitors now
just need a good "tuneup".

Any suggestions on next steps? - given that obtaining a service manual
is highly unlikely, the professionals aren't interested, and my
electronics knowledge doesn't extend much past digital logic circuits?

TIA

Sunny

This kind of question makes me want to open a monitor shop again.

You havent experienced the hassle yet, you think its the metal shielding and
stuff? No, its the way Sony uses matched parts that you typically cant find
replacements for.

So its a 2SD4343whatever transistor, it crosses to an NTE3434 or ? but you
install it and it doesnt work or something else goes out. Whatever Sony
does they seem to have a major hatred for repair shops and design their
equipment to be difficult to repair, Im guessing they apply dummy circuits
that do nothing, except detect if some part is outside of a tolerance %,
then causes a shutdown

There can be exceptions, but spend $40 or ? on the service manual even if
its a similar chassis.

You know about high voltage thats still in the chassis even after the power
is off and cable is disconnected? If you are around monitor circuits get a
standard neon bulb and glue it onto the end of a wooden or hard plastic
stick. get a 5K 10watt resistor and solder a wire on each end, then a
jumper clip to those ends, then clip one side to the chassis ground, and you
can clip the other to a screwdriver metal part and short out possible high
voltage, and put it under the high voltage anode to zero it out also, but
only if the power cord is unplugged

So the big thing is safety, check regulators and workhorse components, if a
regulator went out, chances are a big resistor in that area is also bad;
Caps always go bad

If the one set has a jittery picture is it near a poweredon tv set? or is a
cell phone sitting on top?

"Sunny" wrote in message
...
I recently acquired (from the dumpster) several Sun Microsystems 20"
monitors, model GDM - 20D10, which appear to be Sony Trinitrons on the
inside. They are really nice when working properly, but were
manufactured in 1994 so probably aren't worth sinking $ into.

I'd like to get two of them running to upgrade the 17" pair I'm
currently using.

One worked reasonably well as-is, but was unusable due to severe CRT
burn-in. The others had symptoms ranging from collapsed display to
failure to power on at all.

I made inquiries about professional repair, but nobody was willing to
provide even a diagnostic estimate - they said the chassis is
unreasonably difficult to work on.

I decided to have a go myself, and experienced the difficulties first
hand - the internals are completely surrounded by multiple layers of
metal shielding, with circuit boards mounted to the inside of the
shields all over the place. It takes almost an hour of disassembly just
to check the power supply fuse, and close to another hour to dismount
boards and arrange them such that one can apply power and take
measurements with any degree of safety.

Without going into tedious detail, I've swapped parts around and now
have two working monitors with good CRTs. One is almost perfect, except
for a slight "shimmer" (not sure how else to describe it), while the
other is sharp but exhibits faint retrace lines and has the display
offset to the left about 1/2" further than can be corrected with the
remote control.

It seems to me the remaining problems are minor and could probably be
corrected via internal adjustments, but there are a *lot*, mostly
unlabeled, and I'm well aware that fiddling with them to see what effect
they have is not the recommended approach. Looks like these monitors now
just need a good "tuneup".

Any suggestions on next steps? - given that obtaining a service manual
is highly unlikely, the professionals aren't interested, and my
electronics knowledge doesn't extend much past digital logic circuits?

TIA

Sunny

Bradley1234 wrote:

This kind of question makes me want to open a monitor shop again.

You havent experienced the hassle yet, you think its the metal shielding and
stuff? No, its the way Sony uses matched parts that you typically cant find
replacements for.

So its a 2SD4343whatever transistor, it crosses to an NTE3434 or ? but you
install it and it doesnt work or something else goes out. Whatever Sony
does they seem to have a major hatred for repair shops and design their
equipment to be difficult to repair, Im guessing they apply dummy circuits
that do nothing, except detect if some part is outside of a tolerance %,
then causes a shutdown

There can be exceptions, but spend $40 or ? on the service manual even if
its a similar chassis.

You know about high voltage thats still in the chassis even after the power
is off and cable is disconnected? If you are around monitor circuits get a
standard neon bulb and glue it onto the end of a wooden or hard plastic
stick. get a 5K 10watt resistor and solder a wire on each end, then a
jumper clip to those ends, then clip one side to the chassis ground, and you
can clip the other to a screwdriver metal part and short out possible high
voltage, and put it under the high voltage anode to zero it out also, but
only if the power cord is unplugged

So the big thing is safety, check regulators and workhorse components, if a
regulator went out, chances are a big resistor in that area is also bad;
Caps always go bad

If the one set has a jittery picture is it near a poweredon tv set? or is a
cell phone sitting on top?

Thanks for your response, and the safety warnings.

The symptom on the one you described as "jittery" (I said "shimmer") is
sort of like the effect you get when a TV camera is pointed at a CRT
monitor, only much, much less pronounced - and no, it's not near
anything that might interfere with it, and doesn't get any worse when I
put more running monitors close to it.

I don't have the skills to do component-level diagnosis on these
monitors, that's why I swapped boards until I had two working reasonably
well. I was hoping the minor remaining problems would be within the
range of internal adjustments, are you saying that's not the case?

"Sunny" wrote in message
...

I recently acquired (from the dumpster) several Sun Microsystems 20"
monitors, model GDM - 20D10, which appear to be Sony Trinitrons on the
inside. They are really nice when working properly, but were
manufactured in 1994 so probably aren't worth sinking $ into.

I'd like to get two of them running to upgrade the 17" pair I'm
currently using.

One worked reasonably well as-is, but was unusable due to severe CRT
burn-in. The others had symptoms ranging from collapsed display to
failure to power on at all.

I made inquiries about professional repair, but nobody was willing to
provide even a diagnostic estimate - they said the chassis is
unreasonably difficult to work on.

I decided to have a go myself, and experienced the difficulties first
hand - the internals are completely surrounded by multiple layers of
metal shielding, with circuit boards mounted to the inside of the
shields all over the place. It takes almost an hour of disassembly just
to check the power supply fuse, and close to another hour to dismount
boards and arrange them such that one can apply power and take
measurements with any degree of safety.

Without going into tedious detail, I've swapped parts around and now
have two working monitors with good CRTs. One is almost perfect, except
for a slight "shimmer" (not sure how else to describe it), while the
other is sharp but exhibits faint retrace lines and has the display
offset to the left about 1/2" further than can be corrected with the
remote control.

It seems to me the remaining problems are minor and could probably be
corrected via internal adjustments, but there are a *lot*, mostly
unlabeled, and I'm well aware that fiddling with them to see what effect
they have is not the recommended approach. Looks like these monitors now
just need a good "tuneup".

Any suggestions on next steps? - given that obtaining a service manual
is highly unlikely, the professionals aren't interested, and my
electronics knowledge doesn't extend much past digital logic circuits?

TIA

Sunny

"Sunny" wrote ...

snipped

The symptom on the one you described as "jittery" (I said "shimmer") is
sort of like the effect you get when a TV camera is pointed at a CRT
monitor, only much, much less pronounced - and no, it's not near
anything that might interfere with it, and doesn't get any worse when I
put more running monitors close to it.

I don't have the skills to do component-level diagnosis on these
monitors, that's why I swapped boards until I had two working reasonably
well. I was hoping the minor remaining problems would be within the
range of internal adjustments, are you saying that's not the case?

As far as I know, the later Sun monitors can only be set-up
using software. They use Sony's Digital Alignment Software (DAS).
If you search on Google, using these terms, you should find some
sites. But I've never seen it being used.
And I can't find it on the Sony website.
It *does* exist tho...
This guy's dissertation mentions it, and a little about how it works:
http://tinyurl.com/5qu7d
HTH

--
Regards,
Tom Tobin.
www.acara.co.uk

Hi,
I think you can find schematics for the N1 which is the next model after the
20D10 and VERY similar.
http://fileshare.eshop.bg/index.php?...2&what=search2
the files (3) are SONY-A1.part1.rar and part2, part3 etc. You might find the
20D10 under a similar Sony model number though, the 20SE1T may be the right
one, I think they were the French models...
May help some anyway. Didn't find the 20D10 exactly but the N1 is the 20D20.
Main difference was that the D10 only worked with composite sync and had a
limited scan range (generally didn't go below 1024 x 768) where the 20D20
accepted composite, separate and probably sync on green too. And it would
sync at the lower resolutions 640 x 480 etc. too.
Hope this helps,
Ed Hall


"Sunny" wrote in message
...
I recently acquired (from the dumpster) several Sun Microsystems 20"
monitors, model GDM - 20D10, which appear to be Sony Trinitrons on the
inside. They are really nice when working properly, but were manufactured
in 1994 so probably aren't worth sinking $ into.

I'd like to get two of them running to upgrade the 17" pair I'm currently
using.

One worked reasonably well as-is, but was unusable due to severe CRT
burn-in. The others had symptoms ranging from collapsed display to failure
to power on at all.

I made inquiries about professional repair, but nobody was willing to
provide even a diagnostic estimate - they said the chassis is unreasonably
difficult to work on.

I decided to have a go myself, and experienced the difficulties first
hand - the internals are completely surrounded by multiple layers of metal
shielding, with circuit boards mounted to the inside of the shields all
over the place. It takes almost an hour of disassembly just to check the
power supply fuse, and close to another hour to dismount boards and
arrange them such that one can apply power and take measurements with any
degree of safety.

Without going into tedious detail, I've swapped parts around and now have
two working monitors with good CRTs. One is almost perfect, except for a
slight "shimmer" (not sure how else to describe it), while the other is
sharp but exhibits faint retrace lines and has the display offset to the
left about 1/2" further than can be corrected with the remote control.

It seems to me the remaining problems are minor and could probably be
corrected via internal adjustments, but there are a *lot*, mostly
unlabeled, and I'm well aware that fiddling with them to see what effect
they have is not the recommended approach. Looks like these monitors now
just need a good "tuneup".

Any suggestions on next steps? - given that obtaining a service manual is
highly unlikely, the professionals aren't interested, and my electronics
knowledge doesn't extend much past digital logic circuits?

TIA

Sunny

The shimmer is due to a bad capacitor. Don't remember the location or
value, but do a Google Groups search as I think it was posted here.
David

Ed Hall wrote:

Hi,
I think you can find schematics for the N1 which is the next model after the
20D10 and VERY similar.
http://fileshare.eshop.bg/index.php?...2&what=search2
the files (3) are SONY-A1.part1.rar and part2, part3 etc. You might find the
20D10 under a similar Sony model number though, the 20SE1T may be the right
one, I think they were the French models...
May help some anyway. Didn't find the 20D10 exactly but the N1 is the 20D20.
Main difference was that the D10 only worked with composite sync and had a
limited scan range (generally didn't go below 1024 x 768) where the 20D20
accepted composite, separate and probably sync on green too. And it would
sync at the lower resolutions 640 x 480 etc. too.
Hope this helps,
Ed Hall

Thanks very much, Ed!

Those service manuals appear to apply to VERY similar models, although
mine have remote controls only. I don't suppose you would know how I
could obtain the DAS 5.X Adjustment Software mentioned in Section 3?

Regards,

Sunny

"Sunny" wrote in message
...

I recently acquired (from the dumpster) several Sun Microsystems 20"
monitors, model GDM - 20D10, which appear to be Sony Trinitrons on the
inside. They are really nice when working properly, but were manufactured
in 1994 so probably aren't worth sinking $ into.

I'd like to get two of them running to upgrade the 17" pair I'm currently
using.

One worked reasonably well as-is, but was unusable due to severe CRT
burn-in. The others had symptoms ranging from collapsed display to failure
to power on at all.

I made inquiries about professional repair, but nobody was willing to
provide even a diagnostic estimate - they said the chassis is unreasonably
difficult to work on.

I decided to have a go myself, and experienced the difficulties first
hand - the internals are completely surrounded by multiple layers of metal
shielding, with circuit boards mounted to the inside of the shields all
over the place. It takes almost an hour of disassembly just to check the
power supply fuse, and close to another hour to dismount boards and
arrange them such that one can apply power and take measurements with any
degree of safety.

Without going into tedious detail, I've swapped parts around and now have
two working monitors with good CRTs. One is almost perfect, except for a
slight "shimmer" (not sure how else to describe it), while the other is
sharp but exhibits faint retrace lines and has the display offset to the
left about 1/2" further than can be corrected with the remote control.

It seems to me the remaining problems are minor and could probably be
corrected via internal adjustments, but there are a *lot*, mostly
unlabeled, and I'm well aware that fiddling with them to see what effect
they have is not the recommended approach. Looks like these monitors now
just need a good "tuneup".

Any suggestions on next steps? - given that obtaining a service manual is
highly unlikely, the professionals aren't interested, and my electronics
knowledge doesn't extend much past digital logic circuits?

TIA

Sunny

wrote:

The shimmer is due to a bad capacitor. Don't remember the location or
value, but do a Google Groups search as I think it was posted here.
David


Thanks David!

I did several Google Groups searches, but didn't find the post you are
referring to. Perhaps you remember the specific search terms?

Thanks,

Sunny

Search using sun sony to find it. Wavy on sides of image.
C637 high esr/open.