Advice requested: Erratic colour fault on computer monitors.

[Tim Polmear]

Hello

I wonder if anyone can give some advice regarding a little problem.

I have a couple of CRT monitors that exhibit similar problems. One
flashes yellow (blue gun fault I guess) and the other flashes magenta
(green gun fault?). It seems to be an electromechanical fault because
both monitors respond to percussive maintenance, but the problem soon
reappears. The monitors are a few years old.

Can anyone guess what the problem is likely to be and do you think it
would be worth having them repaired? (The answer to the latter is
probably no.)

Regards,
Tim Polmear

 

[Rod Speed]

I wonder if anyone can give some advice regarding a little problem.

I have a couple of CRT monitors that exhibit similar problems. One
flashes yellow (blue gun fault I guess) and the other flashes magenta
(green gun fault?). It seems to be an electromechanical fault because
both monitors respond to percussive maintenance, but the problem soon
reappears. The monitors are a few years old.

Can anyone guess what the problem is likely to be

Likely a bad solder joint on the pcb on the neck of the tube.

and do you think it would be worth having them repaired?

Really depends on whether you can find someone
who wont charge much to resolder that area.

(The answer to the latter is probably no.)

Depends on how big they are. If they're 15" monitors and you
have to pay someone to repair them and cant find someone
who is prepared to resolder that area cheaply, likely not.

If they're big trinitron monitors, maybe.

 

[Rudolf Ladyzhenskii]

Bad solder on CRT PCB or bad video cable.

Where are you?

Rudolf

 

[Tim Polmear]

Thanks for pointing me in the right direction Rod -

 

[Tim Polmear]

Hit Rudolph. I'm in Moora WA. It's a bit out of the way getting stuff
repaired unless I take them down to service centres in Perth.

 

[John G]

This type of problem is sometimes caused by bad (loose )
contacts in the connectors.
Eithe the cable end at the PC or sometimes inside the
monitor if the cable is plugged to the board

 

[Bill Ruys]

Without thumping the monitor, the next time the problem occurs, move the
video cable around. Does the problem come and go as you do this?

I find in about 80 to 90% of cases, the problem is intermittent open
circuits in the video cable. Basically the conductors break in the cable
from movement over the years. Occasionally it is due to dirty pins in the
sub miniature DB15 too.

Bill.

 

[Tim Polmear]

But thumping is so much fun

Thanks Bill. I'll have a go at wiggling the cable when I get back to
work and see what happens.

Tim Polmear