broken monitor: dropped

[gimho]

i have a dell branded 17" trinitron which accidentally fell off the
table. the monitor still powers up alright, but the image isn't right.
the left fifth of the screen is fine, but in the right 4/5ths of the
screen, it seems like the RGB signals are mixed up.

my question is, is this repairable? i have a modest electronics
background and am willing to put in the time, but need some help to
point me in the right direction. many thanks in advance.
-dave

 

[CJT]

i have a dell branded 17" trinitron which accidentally fell off the
table. the monitor still powers up alright, but the image isn't right.
the left fifth of the screen is fine, but in the right 4/5ths of the
screen, it seems like the RGB signals are mixed up.

my question is, is this repairable? i have a modest electronics
background and am willing to put in the time, but need some help to
point me in the right direction. many thanks in advance.
-dave

That sounds (to me) like deformation of the CRT internals. It's
probably time for a new monitor.

 

[Jerry G.]

Most likely the CRT has been damaged. The fact that you have a picture
and the controls all work, means that the electronics are probably okay,
and the circuit board is most likely not broken anywhere. The mask in
the CRT probably became bent in the fall. The replacement cost of the
CRT (if it was even available) would exceed the cost of the monitor.

--

Jerry G.
======

i have a dell branded 17" trinitron which accidentally fell off the
table. the monitor still powers up alright, but the image isn't right.
the left fifth of the screen is fine, but in the right 4/5ths of the
screen, it seems like the RGB signals are mixed up.

my question is, is this repairable? i have a modest electronics
background and am willing to put in the time, but need some help to
point me in the right direction. many thanks in advance.
-dave

 

[John Gill]

dave:
I would try to degauss the tube with an external manual degaussing
coil. Like they used to do when TV's first came out.
If that does not work, I would think that the shadow mask within
the picture tube has shifted somewhat. In that case, you have to
replace the CRT tube or purchase a new monitor.
John

 

[Allodoxaphobia]

i have a dell branded 17" trinitron which accidentally fell off the
table. the monitor still powers up alright, but the image isn't right.
the left fifth of the screen is fine, but in the right 4/5ths of the
screen, it seems like the RGB signals are mixed up.

That's what my wife did when she wanted a new LCD monitor.
She is quite happy with her brand new LCD monitor.

my question is, is this repairable? i have a modest electronics
background and am willing to put in the time, but need some help to
point me in the right direction. many thanks in advance.

Check in with the "computer departments" of Goodwill, The
Salvation Army, ARC, etc. People other than my wife simply pass
along their CRT monitors to them when _they_ want a brand new
LCD monitor. I've seen them priced as low as $20.

Jonesy

 

[Wild Bill]

I believe the internals of the CRT have shifted. I've seen the internal
framework of Sony trinitron tubes, and wouldn't have thought that this was
likely, but I've been convinced that this is possible.
Some cheaper CRTs use a flimsy construction for the mask, but the Sony tubes
appear to be very rugged.

The colored lines are sometimes cmpared to the old Atari logo, in that they
seem to arc in opposite directions from the point of the fault.

Cheers
WB
.......................

 

[William R. Walsh]

Hi!

As others have said, the internals of the tube (shadow mask, or whatever
similar means it uses) have likely shifted, which is causing the problem you
see. A manual degaussing may help at this point, but it isn't likely to
change much about the problem you're seeing.

The monitor is not truly "fixable" short of putting a new tube in it, but
you could possibly acheive an acceptable "correction" with magnets placed on
the tube near the damaged part of the picture. If you have some magnets and
glue, and are comfortable working inside a monitor (meaning that you know
how to stay away from that which could bite you!) it would be worth trying
before discarding the monitor.

William

 

[Sam Goldwasser]

Hi!

As others have said, the internals of the tube (shadow mask, or whatever
similar means it uses) have likely shifted, which is causing the problem you
see. A manual degaussing may help at this point, but it isn't likely to
change much about the problem you're seeing.

The monitor is not truly "fixable" short of putting a new tube in it, but
you could possibly acheive an acceptable "correction" with magnets placed on
the tube near the damaged part of the picture. If you have some magnets and
glue, and are comfortable working inside a monitor (meaning that you know
how to stay away from that which could bite you!) it would be worth trying
before discarding the monitor.

While that is a possible technique and probably mentioned in the monitor
and TV repair guides, as a practical matter with a high res computer monitor,
while the magnets may fix the purity problem, they will likely introduce
some geometric distortion which can be at least as annoying.

--- sam | Sci.Electronics.Repair FAQ Home Page: 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 Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

 

[William R. Walsh]

Hi!

While that is a possible technique and probably mentioned in the monitor
and TV repair guides, as a practical matter with a high res computer monitor,
while the magnets may fix the purity problem, they will likely introduce
some geometric distortion which can be at least as annoying.

Yes, that's where it came from. I think it is in your repair briefs
somewhere--I read that tip and tried it on an 8513 that took a trip down
some stairs. After some careful magnet work the monitor was pretty well
fine. There was some geometric distortion, but nothing too bad and since the
monitor was viewed from a distance it didn't really matter in the end.

Worth a try at the very least...

William

 

[James Sweet]

Most likely the CRT has been damaged. The fact that you have a picture
and the controls all work, means that the electronics are probably okay,
and the circuit board is most likely not broken anywhere. The mask in
the CRT probably became bent in the fall. The replacement cost of the
CRT (if it was even available) would exceed the cost of the monitor.

I have a 17" Trinitron CRT that the O.P. can have for free if they're in the
Seattle area, I'll remove it from the dead monitor it's in.

 

[gimho]

dear all,
i really appreciate all your help. i think i'll try manual degausing,
and if that doesn't work, i'll buy a new monitor (lcd's are still a
little pricey). but before i do, would someone please confirm that a
damaged CRT would cause what i'm seeing here? thanks again.
http://128.59.144.136/s.e.repair/
-dave

 

[Quadrajet1]

dear all,

i really appreciate all your help. i think i'll try manual degausing,
and if that doesn't work, i'll buy a new monitor (lcd's are still a
little pricey). but before i do, would someone please confirm that a
damaged CRT would cause what i'm seeing here? thanks again.
http://128.59.144.136/s.e.repair/
-dave

Sure looks like it to me, and I've seen a bunch of them. Get a new monitor!
You may be able to find a good used CRT, but then you'd have lots of adjusting
to do to make it perfect.

Raymond

 

[Wild Bill]

That's a clever test pattern.
The mis-alignment appears to be very uniform.. maybe someone else could
comment on the possibility of a shifted yoke (although that may be
unlikely).

Cheers
WB
..............

 

[Tom MacIntyre]

i have a dell branded 17" trinitron which accidentally fell off the
table. the monitor still powers up alright, but the image isn't right.
the left fifth of the screen is fine, but in the right 4/5ths of the
screen, it seems like the RGB signals are mixed up.

I am familiar with that test pattern. It is called (in my
recollection) the SMPTE pattern. When I was in TV broadcasting I used
it for monitor alignment. The third bar combination (cyan over
magenta) and the fifth (magenta over cyan) share a common colour,
blue. Kill R (for the magenta) and G (for the cyan), and use the phase
adjustment to match the two bars so there is no small and large bar,
they are solid blue, and your monitor is dead on for colour/purity.
That being said...

Your colour/purity problem is occuring much earlier than you think. By
the time you get to the fifth bar in the first pattern, the cyans and
magentas have no similarity. The scan is falling or rising, and
hitting the wrong phosphors. This is likely an aperture grill CRT, in
which the "shadow mask" is like vertical blinds, so vertically,
anything goes. Whatever controls the accuracy of the scan vertically
has been ever so slightly compromised.

Tom

 

[James Sweet]

dear all,
i really appreciate all your help. i think i'll try manual degausing,
and if that doesn't work, i'll buy a new monitor (lcd's are still a
little pricey). but before i do, would someone please confirm that a
damaged CRT would cause what i'm seeing here? thanks again.
http://128.59.144.136/s.e.repair/
-dave

Yes that's most definitly a damaged CRT, either that or the deflection yoke
shifted a good bit.

 

[Wayne Tiffany]

If it were a shifted yoke, wouldn't that affect the whole screen, not just
the RH portion?

WT

 

[James Sweet]

If it were a shifted yoke, wouldn't that affect the whole screen, not just
the RH portion?

WT

Probably, but it's still worth checking before chucking the thing.

 

[Tom MacIntyre]

If it were a shifted yoke, wouldn't that affect the whole screen, not just
the RH portion?

WT

It isn't just affecting the RH portion, it's a gradual thing, and the
repeated bar pattern confirms that.

Tom