CRT monitor turned purple

Hi everyone, I'm new here. I should say that I'm not any kind of an expert on computer hardware so please go easy on the jargon if you can.

Our old CRT monitor started to turn purple intermittently (the screen, that is! :-D ), i.e. the green pixels would cut out almost completely. If it had just that moment turned purple and was flickering, hitting it would often get it back to normal, but once it had settled down that wouldn't work. Eventually it got so it was purple nearly all the time, so we gave up on it. I like CRTs so much better than LCDs that we got another CRT secondhand off EBay. We've had that one for about a year, but now that's started turning purple, too.

I stumbled across this forum while trying to find out whether there was anything less horrid than an LCD currently on sale and did some searches, and came across this: Anyone have a card die like this?
So is this just the way CRT monitors do die, or is it something to do with a circuit board and possibly fixable? If so, what's likely to be the culprit - something inside the monitor itself, or the computer's video card? Inside the monitor seems the obvious answer, but it seems odd to me (knowing nothing about monitors) that they would both fail in exactly the same way.

Just a long shot. If anyone can answer that would be great.

It is the monitor itself.

Could be something as simple as a bad connection on the CRT or a faulty solder connection on the circuit board.

Could be many things. Sounds like you lost your green signal. I don't think the green gun in your tube went out. They usually don't self-destruct or just "blow" so it's most likely a video connection issue. What kind of model is this? Strange that the other one is turning purple too.

the monitor should have a self test or something which shows a red,green, and blue areas so that you can check if a gun is dead
i think usually you can activate it by pulling out the vga cable

Thank you, everyone. Right, the monitor doesn't exactly have a self-test, but if you pull out the VGA cable it says "Check Connection"... and it now says it in purple. So it's not the connection to the computer.

It's a ViewSonic E72f+. The other one was a Phillips something (no longer got it).

Since hitting it sometimes stops it, presumably it's a loose contact of some sort? Is that that, then? I can't remember whether you even can take the back off a CRT monitor.

Realistically you are not going to fix anything by opening up the monitor. More likely you'll kill yourself with a shock from the flyback.

I'm curious why you are dead set on staying CRT? is it an eyestrain issue? I could not leave CRT fast enough. Heck I still have my original gangster Dell 24" that I paid $1200 for.

A. B. said:

Thank you, everyone. Right, the monitor doesn't exactly have a self-test, but if you pull out the VGA cable it says "Check Connection"... and it now says it in purple. So it's not the connection to the computer.

It's a ViewSonic E72f+. The other one was a Phillips something (no longer got it).

Since hitting it sometimes stops it, presumably it's a loose contact of some sort? Is that that, then? I can't remember whether you even can take the back off a CRT monitor.

Click to expand...

So next up is the video amplifier. Most likely the green circuit is out. I'm going to assume here that the tube itself isn't the culprit (hope it isn't). But usually - guns don't simply "go out" in a flash. They usually get weak and go dim before they really die. I'm positively certain that the problem is somewhere on the video amplification path.

Yup, violence wouldn't revive a dead gun, so it's a problem in the signal path. I'm guessing bad solder junction, burnt/shorted wires.
Please, do not take the cover off.
The glass is charged to deadly voltages and may still harm you solely from charge stored in capacitors hours after it's been off. And who knows, if it's a short, that voltage can appear somewhere you wouldn't expect.
However any semi decent fix-it man should verify this theory by simply reflowing the junctions with an iron.

http://lowendmac.com/2007/the-truth-about-crts-and-shock-danger/

probably not that dangerous but still no point to poking around in there unless you know beforehand what you're doing

Looks like the Randy Fromm CRT monitor repair video series isn't online anymore - close to 8 hours of goodness. Glad I backed the videos up before that happened

I'll try zipping them up and uploading them somewhere, they'll definitely be helpful for someone attempting to navigate CRT repair (safely).

It could be a failed RAMDAC in the GPU... I've had messed up cards that have sent color casts over analog only. Try a known-good card to see what the problem is.

rabidz7 said:

It could be a failed RAMDAC in the GPU... I've had messed up cards that have sent color casts over analog only. Try a known-good card to see what the problem is.

Click to expand...

Or it could be a reading comprehension failure... "but if you pull out the VGA cable it says "Check Connection"... and it now says it in purple"

OK, fair enough. Just thought it was worth asking before giving up on the thing. Won't attempt checking those connections myself, though might consider showing it to a computer repairer (who might actually know where that power supply IS so as to avoid touching it. That seems to be the one thing that article doesn't think to mention!).

gunbust3r said:

I'm curious why you are dead set on staying CRT? is it an eyestrain issue? I could not leave CRT fast enough. Heck I still have my original gangster Dell 24" that I paid $1200 for.

Click to expand...

It's not eye-strain exactly; after working at an LCD screen for more than a few minutes I get jittery and can't concentrate on what I'm doing. Regular breaks help a bit but don't solve the problem completely. (Also when I get into that state I tend to just press "Skip" on the break prompt before I even think what I'm doing!) I get this every time on my laptop, but on the old CRT I'm fine. I'm told that this phenomenon doesn't really exist, and that if it does exist, LCDs are much better for it than CRTs; but I'm afraid my eyeballs aren't impressed by this information! Maybe it's psychosomatic, but that doesn't really make much difference to the end result.

The circuit boards on CRT monitors, TV's, etc. are generally all marked by a thin line that denotes what circuits are what.

Having taken apart numerous CRT monitors and TVs, from my perspective, it is very unlikely you will shock yourself unless you have the thing plugged in while working on it.

And to make sure the capacitors are discharged before you open it up, you can just turn the power switch on after unplugging it.

Nothing but the capacitors are going to hold any type of charge. The flyback is basically just a transformer, and the CRT is just a tube. Once power is removed, there is no danger from either of those.

The flyback will also have a focus and a brightness adjustment on it. Whenever I opened up a CRT that didn't already have holes in the monitor case to adjust these I would drill holes so I could adjust them if need be.

Since you said that hitting it sometimes fixes it, my guess would be that the plug that connects directly onto the back of the CRT just needs to be reseated.

If that doesn't fix it, then you most likely just have a bad solder connection.

Another good thing to do is to blow the dust off of everything right after opening it up. You can use canned air or, better yet, an air compressor with an air nozzle to do so.

If you definitely don't feel confident about opening it up, take it somewhere. Any good TV repair place should be able to fix it. Just make sure that they are not going to charge you for an estimate.

A. B. said:

It's not eye-strain exactly; after working at an LCD screen for more than a few minutes I get jittery and can't concentrate on what I'm doing.

Click to expand...

It might be a PWM backlight. Some people react pretty badly to them. Try tracking down a non PWM model to look at.

I had a Sony G520P CRT that would turn red intermittently the last couple months I owned it (Before it quit working altogether) I was told it was probably a cold solder joint somewhere which might explain why hitting it sometimes took the red away, but I never had it looked at..