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CRT Monitor Convergence

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SolidxSnake

Member
Joined
Dec 26, 2004
Anyone here have any experience with CRT repair? My several year old (4-5 years) Viewsonic A90f+ has a slight convergence problem on the bottom of the monitor (the reds are out of alignment horizontally). I am wondering how hard it would be to fix, it's not too much of a problem but it does bug me every so often. I've read up on how to adjust convergence on CRT monitors and it doesn't sound too hard but I'd like to see exactly what the process is (pics would be a great help). Also, proper handling of a CRT. I've worked with power supplies, amplifiers and flash guns, but never a CRT, so I know the basic safety of working on dangerous devices, but don't know the exact procedure for a CRT.

My google skills are failing, I've found only one helpful article on CRT convergence but it is all text so I'm having slight troubles visualizing exactly what to do.
 
Usually those adjustments and what not are only available once you have the case off the thing. Im not sure if you have to discharge the monitor or not, but you will most likely want to just to be sure you dont kill yourself. I know there is plenty of stuff on google about discharging crt's. I remember some of the older crt's had adjustments that you could make by using a long flat head screw driver in a set of holes. Im sure the newer crts abandoned this and have all that stuff internal. So im betting you will have to take it completely out of its case and see if you can find some sort of manual controls that you can tweak.

If i were you i would send an email to the monitor manufacturer asking for some info maybe some documentation etc. it wouldnt hurt. Maybe you will get lucky and find some old CRT repair dude there that can walk you through it with pics and the like.
 
Regarding safety, there are quite a few high voltage spots. The biggest being the one that actually connects to the tube...you should not even be removing that, so just leave it alone :p. It is quite fun to discharge (had to work on CRT's at my last job, replacing, etc) and has one hell of a shock if it hits you.

Besides that, normal electronics safety apply.
 
I know it's only available under the cover, that's what I need some help with.

From what I've seen, there is a rubber cap (looks like a suction cup) that covers a clip that clips onto the CRT which needs to be connected to the chassis to discharge it (I'm not sure if I should just short it and risk damaging anything or if I should get a CRT Discharge tool in order to slowly discharge it with high-power resistors). From there, I think there are several adjustment rings on the guns which adjust convergence and purity. Since I have no purity problems, I leave those alone.
 
I know it's only available under the cover, that's what I need some help with.

From what I've seen, there is a rubber cap (looks like a suction cup) that covers a clip that clips onto the CRT which needs to be connected to the chassis to discharge it (I'm not sure if I should just short it and risk damaging anything or if I should get a CRT Discharge tool in order to slowly discharge it with high-power resistors). From there, I think there are several adjustment rings on the guns which adjust convergence and purity. Since I have no purity problems, I leave those alone.
You have to discharge it to calibrate it?!

I've always taken a glove (insulated), long screw driver and shorted (with it still in the tube) to the frame. Never had an issue. I know I'm going to have people yelling at me for that one.
 
You have to discharge it to calibrate it?!

I've always taken a glove (insulated), long screw driver and shorted (with it still in the tube) to the frame. Never had an issue. I know I'm going to have people yelling at me for that one.

Actually I don't think you do, but I want to know how to in case I do need to. I actually think I have to have the monitor on and running while converging the beams.
 
Actually I don't think you do, but I want to know how to in case I do need to. I actually think I have to have the monitor on and running while converging the beams.
I'm sure you shouldn't have to discharge the tube to just adjust it :p
 
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