Monitor CTM644

[Dagger]

I know there is a way of boosting the brightness on these monitors by altering one of the variable resistors, but is there away of altering the RGB? One of my monitors has a strong red tint. The other colours are ok, just the red is too strong.

[||C|-|E||]

There is a way to adjust color vias, yes, but you have to open the screen and adjust it when it is working. The variable resistors, if I recall properly, are VR801, VR802 and VR803. They are described in the service manual 

[Dagger]

Thank you for the response. Is there a reason why it has to be adjusted while the monitor is on? Just sounds a bit dangerous 

[chinnyhill10]

Thank you for the response. Is there a reason why it has to be adjusted while the monitor is on? Just sounds a bit dangerous 

So you can see what you are adjusting.


And yes it is dangerous. Wouldn't catch me anywhere near the insides of a CRT. People seem to open them up and take risks without knowing what the dangers are.

[||C|-|E||]

Yup, as Chinny says, you need to see what the screen is displaying it order to adjust it. Ideally, you would be also displaying a predefined color chart for a better adjustment  Manipulating a live CRT, even if it is not very big, is certainly a bit on the risky side if you are unfamiliar with them...

[Bryce]

If you stick to the safety rules the risk isn't all that high. The rules:

- Don't open or move the monitor while it's plugged in - ie: power it up after you have opened it completely. Have it in a position that you can see both the front and the back without having to move it.

- Don't touch anything inside with your fingers. Especially metal things, solder joints and PCB traces.

- The "one handed rule": Use an insulated screw driver to make adjustments and keep your other hand behind your back or in your pocket while doing so.

- Unplug it again before you put it back together.

Most people who do get a jolt from CRTs, get it when putting the monitor back together. The capacitors are all charged and while trying to get the PCB aligned with the case they inadvertantly touch the PCB. If you need to touch the PCB during re-assembly, do it with something plastic.

Bryce.

[||C|-|E||]

Once extra thing I always do is to wear nitrile gloves, they are very thin, resistant and a great insulator 

[Bryce]

I don't use gloves, because it's then too tempting to touch something with your hand. Not a huge issue with a CRT, but if you've ever worked on things above 10KV, you stop trusting gloves.

Bryce.

[||C|-|E||]

hahaha, you need to work as if you were not using them! 

[Gryzor]

Depending on where those resistors are located, of course, a mirror can be of help...