KTX 17" (CAG664-SG) - no red

[Dino]

I was given this monitor a while back, and at the time, it had intermittent
colour problems. Turns out it was dry joints on the vga connector.
Since then, it's been running fine untill a few days ago, when it lost red
completely. Even in the OSD. I know the red gun is still firing, as I can
adjust the drives and cutoffs in the menu, when I turn the red cutoff up, I
see red at the edges of the screen where there is no picture, and if I turn
it up more, I get diagonal red lines across the entire screen. The red
drive adjustment is apparently doing nothing. (I can see a difference when I
adjust the blue or green drive controls)

I am relatively new to monitor repairs, and so far have only done basic
stuff such as replacing cables, and repairing power supplies. Can anyone
point me in the right direction?

- D Doyle

 

[Asimov]

"Dino" bravely wrote to "All" (21 Dec 04 08:09:44)
--- on the heady topic of "KTX 17" (CAG664-SG) - no red"

Di> From: "Dino" <[email protected]>

Di> I was given this monitor a while back, and at the time, it had
Di> intermittent colour problems. Turns out it was dry joints on the vga
Di> connector. Since then, it's been running fine untill a few days ago,
Di> when it lost red completely. Even in the OSD. I know the red gun is
Di> still firing, as I can adjust the drives and cutoffs in the menu, when
Di> I turn the red cutoff up, I see red at the edges of the screen where
Di> there is no picture, and if I turn it up more, I get diagonal red
Di> lines across the entire screen. The red drive adjustment is
Di> apparently doing nothing. (I can see a difference when I adjust the
Di> blue or green drive controls)
Di> I am relatively new to monitor repairs, and so far have only done
Di> basic stuff such as replacing cables, and repairing power supplies.
Di> Can anyone point me in the right direction?


Perhaps your original dry joint problem has struck again but
alternately the vga plug may have a broken or bent pin. However, it is
possible your monitor's cable may have a single broken wire for the
red signal. The break will often be close to one end. Check the red
signal wire with an audible continuity tester (buzzer, beeper, etc)
while gently twisting the cable. Listen to the steady tone for
scratchy type sounds as you manipulate the cable.

Good luck!
A*s*i*m*o*v

.... :<) What does that wire do? =8<Q (oh!)

 

[[email protected]]

Many intermittant color problems are due to a break in the video cable.
Try
bending the cable, near where it goes into the computer. If the color
comes back, you can replace the 15 pin HD
connector to fix the problem.
John

 

[Dino]

What difference would the video cable make to the monitor's OSD?
I tried another cable anyway (Removable on this monitor), same effect.
I also tried another video card.
I've tested the connection from the pins on the socket at the back of the
monitor to the pins they connect to (via an internal cable) on the board
that attatches to the back of the crt. there are no missing signals, and no
shorts between them (except for the various grounds, becoming only two wires
in the internal cable. One for rgb return - pins 6, 7, and 8. And one for
pins 5 and 10 of the vga connector)

This is no longer an intermittant problem.

 

[Asimov]

"Dino" bravely wrote to "All" (21 Dec 04 17:10:35)
--- on the heady topic of "Re: KTX 17" (CAG664-SG) - no red"

Di> From: "Dino" <[email protected]>

Di> What difference would the video cable make to the monitor's OSD?
Di> I tried another cable anyway (Removable on this monitor), same effect.
Di> I also tried another video card.
Di> I've tested the connection from the pins on the socket at the back of
Di> the monitor to the pins they connect to (via an internal cable) on the
Di> board that attatches to the back of the crt. there are no missing
Di> signals, and no shorts between them (except for the various grounds,
Di> becoming only two wires in the internal cable. One for rgb return -
Di> pins 6, 7, and 8. And one for pins 5 and 10 of the vga connector)

Di> This is no longer an intermittant problem.

It's a video not getting to the colour processor IC issue then. Check
whatever goes inbetween the main board's vga socket and the colour
processor IC. Since the OSD is fine this means the colour IC is fine
(along with everything else that goes after it). I bet there's a
hairline crack in the red pcb pad at the vga socket (pin 1).

A*s*i*m*o*v

.... If all else fails, hurl it across the room a few times!

 

[Dino]

"Dino" bravely wrote to "All" (21 Dec 04 17:10:35)
--- on the heady topic of "Re: KTX 17" (CAG664-SG) - no red"

Di> From: "Dino" <[email protected]>

Di> What difference would the video cable make to the monitor's OSD?
Di> I tried another cable anyway (Removable on this monitor), same effect.
Di> I also tried another video card.
Di> I've tested the connection from the pins on the socket at the back of
Di> the monitor to the pins they connect to (via an internal cable) on the
Di> board that attatches to the back of the crt. there are no missing
Di> signals, and no shorts between them (except for the various grounds,
Di> becoming only two wires in the internal cable. One for rgb return -
Di> pins 6, 7, and 8. And one for pins 5 and 10 of the vga connector)

Di> This is no longer an intermittant problem.

"Asimov" replied

It's a video not getting to the colour processor IC issue then. Check
whatever goes inbetween the main board's vga socket and the colour
processor IC. Since the OSD is fine this means the colour IC is fine
(along with everything else that goes after it). I bet there's a
hairline crack in the red pcb pad at the vga socket (pin 1).

... If all else fails, hurl it across the room a few times!

As stated in my original post: '...it's been running fine untill a few days
ago, when it lost red completely. Even in the OSD.'

The only red I see is if I turn the red-cutoff up(down? In the OSD, I'm
increasing it, but from my understanding of things, I'd assume I'm actually
turrning it down...), and then it's a whole screen thing, not just where
it's supposed to be.

So, since the OSD is not displaying red either, is it likely to be the
colour IC?
If so, I'm thinking it's likely going to be a bit difficult to find a
replacement, or replace it myself if I can.

 

[Asimov]

"Dino" bravely wrote to "All" (22 Dec 04 13:04:36)
--- on the heady topic of "Re: KTX 17" (CAG664-SG) - no red"

Di> From: "Dino" <[email protected]>

Di> As stated in my original post: '...it's been running fine untill a few
Di> days ago, when it lost red completely. Even in the OSD.'

Di> The only red I see is if I turn the red-cutoff up(down? In the OSD,
Di> I'm increasing it, but from my understanding of things, I'd assume I'm
Di> actually turrning it down...), and then it's a whole screen thing, not
Di> just where it's supposed to be.

Di> So, since the OSD is not displaying red either, is it likely to be the
Di> colour IC?
Di> If so, I'm thinking it's likely going to be a bit difficult to find a
Di> replacement, or replace it myself if I can.

Sorry, I misunderstood that the OSD had the *right* colour. Ah, but if
the red is also missing in the OSD then you might try swapping a
colour line to the neck board (if the colour IC is on the main board).
If the problem stays with red then it is either the driver transistor
(and associated circuitry) or the crt itself. If it moves to another
colour then the problem lies with the colour processor onwards.

A*s*i*m*o*v

.... :<) What does that wire do? =8<Q (oh!)