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Monitor repair *now with 100% more pics*

J

jagec

Lifer
My monitor's been having trouble...anytime you want to display something bright (white's the worst), it will jitter like mad. It comes and goes, but it's been getting worse. Sometimes whacking it fixes it for a while, so I was thinking loose connection, and I took it apart to check.
taking it apart
circuit boards looked fine...
power supply looked fine...
but that little purple light along the left? It was going on and off in time with the jittering of the monitor. If it's not the problem, it's related...does anyone know what that is/what it does?
 
It's a small neon bulb. It's probably to indicate whether voltage is present. I think they are also sometimes used to suppress arcing.
 
I'm starting to think this is over my head...are there still repair shops that do monitors? How much would it cost?
 
I am betting it is suppressing arcing from a relay's contacts.

I doubt it has anything to do with your trouble, though.
 
Hi, First relpy went astray, so am trying again. This won't be much help with your monitor problem, but might help you understand the Neon Bulb bit. A neon bulb and one resistor makes a real cheap 55 Volt regulator. I am surprised to see one in a modern monitor or any monitor for that matter. They were used as regulators many, many years ago. They act as regulators for the same reasons that they work as starters for flourescent lamps. Jim
 
Originally posted by: JimPhelpsMI
Hi, First relpy went astray, so am trying again. This won't be much help with your monitor problem, but might help you understand the Neon Bulb bit. A neon bulb and one resistor makes a real cheap 55 Volt regulator. I am surprised to see one in a modern monitor or any monitor for that matter. They were used as regulators many, many years ago. They act as regulators for the same reasons that they work as starters for flourescent lamps. Jim
Click to expand...

huh, that's interesting...so it going out and coming back on probably means the voltage is fluctuating, yes? I wonder where my short is...
 
Hi, I forgot that Neon Bulbs also make great osicillators with one resistor and one capacitor. Failure of one component in a circuit could alter the action of the bulb. Your short idea may be good. Unless you are an electronic tech, you probably should not try to fix it. I used to repair a few, but today's monitors are so complicated it's not worth the trouble. Good used 17" monitors are around $35.00 at the Chicago area Computer shows. New ones are resonable now. Luck,Jim
 
My monitor also has been acting up lately. Every once in awhile the green indicator lite goes off and the
screen gets dark. After a number of seconds it comes back on by itself. Also I have been noticing that
when I first turn on the Computer the monitor will not come on. If I shutdown and restart it will then come on. It's pushing about five years old and still looks great. LG Studioworks 995E. My video card a
Geforce3-Ti-200 is also pushing four years. Which is more likely to be the problem?
 
Originally posted by: jagec
My monitor's been having trouble...anytime you want to display something bright (white's the worst), it will jitter like mad. It comes and goes, but it's been getting worse. Sometimes whacking it fixes it for a while, so I was thinking loose connection, and I took it apart to check.
taking it apart
circuit boards looked fine...
power supply looked fine...
but that little purple light along the left? It was going on and off in time with the jittering of the monitor. If it's not the problem, it's related...does anyone know what that is/what it does?
Click to expand...

Sounds like my monitor - it would get all squished at the left and right sides, and stretched in the middle. Hitting the monitor would sometimes make the problem go away momentarily. Yes - loose connection somewhere.
After a lot of sophisticated diagnostics (prodding the circuit board with a stick with the monitor on), I found that it was a single cracked solder joint. It's under the project section of my website. I'll be changing the directory structure around a bit in the next few days, so that's why I'm not giving a direct link. 😎


Edit: Ah, there, that was painless. Direct Link. Rather proud of my limited, yet apparently flexible HTML programming, if I may say so. 🙂
 
ROFL at the comments posted here.

That looks to be a spark gap to prevent other parts of the circuit getting damaged in the event of EHT leakage from the flyback transformer (FBT) which is that big monster to the left of the spark gap and has the big thick red wire going to the back of the CRT, this wire is called the final anode and only carries a measly 26,000 volts and just enough current to only kill half a dozen people so dont be too concerned about taking it apart and touching bits or general safety... Oh, they also hold their charge, usually only for a few years so again, dont be too concerned about touching bits of the circuit if the unit is unplugged.

Sure, it could be a neon but I have never seen a neon used in the thousands of monitors I've repaired over the years.

If you're jittering the monitor and its coming on and off, it will most likely be a dry solder joint as Jeff7 states. Play with it at your own risk. These things can and do kill people that dont know much about electronics.
 
i suggest you stop whatever you are doing. a crt is not to be messed around with unless you are highly trained at repairing it!!!!!!!
 
I would have to agree with jayn. Especially where I live in a big city, I've seen 17 inch monitors(they are almost worthless) thrown out on street corners because a lot of people are switching over to LCD monitors.
 
Originally posted by: MercenaryForHire
If you have to ask what's wrong with a CRT, you should not be fixing it. Close it up and get a new one.

- M4H
Click to expand...

Ditto, beware - being a tight wad kills occasionally.
 
Originally posted by: jagec
I'm starting to think this is over my head...are there still repair shops that do monitors? How much would it cost?
Click to expand...

Most likely it would cost more than a new monitor. Also, don't play around inside that thing, it can kill you.
 
Yeah, I couldn't think of "gas discharge tube" so I said neon. 😀

Spark gaps and gas discharge bulbs on CRT neck board or elsewhere
These are protective devices intended to breakdown and divert excessive voltage away from the CRT (usually).

Spark gaps may be actual two or three pin devices with seemingly no insides or printed on the circuit board itself.

Gas discharge bulbs look like small neon lamps (e.g., NE2) but could be filled with some other gas mixture to provide a controlled higher breakdown voltage.

Arcing at a spark gap or a flashing or glowing gas discharge tube may indicate excessive high voltage, a short in the focus/screen divider network of the flyback, a short in the CRT, or some other fault resulting in abnormally high voltage on its terminals.
Click to expand...

 
I really wouldn't be messing around with that stuff if I was you.

You clearly don't really know what you're doing, and one wrong move can kill you.
 
I really enjoyed your article about the scannerPC. Very neat. I just happen to have an even older scanner lying around (required a ISA adapter card), and an old Dell 400MHz, that I have no more use for.

You have given me an idea for a new winter project to keep me out of the wifes hair.
 
Originally posted by: Bozz
That looks to be a spark gap to prevent other parts of the circuit getting damaged in the event of EHT leakage from the flyback transformer (FBT) which is that big monster to the left of the spark gap and has the big thick red wire going to the back of the CRT, this wire is called the final anode and only carries a measly 26,000 volts and just enough current to only kill half a dozen people so dont be too concerned about taking it apart and touching bits or general safety... Oh, they also hold their charge, usually only for a few years so again, dont be too concerned about touching bits of the circuit if the unit is unplugged.
Click to expand...

I know what it is, I know how much voltage it carries, and I know how long they've been known to carry it.

I may not know exactly how a monitor works, but I certainly know the basics of a cathode ray tube, and I know what not to touch. I've been screwing around with electronics since I was 7, this is just the first time I've messed with a monitor.

It's just that right now I don't have ANY money, and I've really gotten addicted to large screens. I'd buy a 1900FP right now if I could afford it, but I'd really prefer to save the money and fix my monitor.

I'll try reflowing the solder joints on the flyback.
 
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