Repairing monitors

[viking1966]

I have 2 19 inch crt monitors that run fine but after awhile they both turn off.. and when i turn them back on the time they stay on becomes shorter and shorter until finally it is just seconds.. I want to take them apart myself and find out why they do that. I think it is a heat problem but nobody on the internet can give me a better answer than go buy a new monitor.. .. think of the money i would save if it was just a fuse or capacitor that needed replaced..

The monitors behave this way no matter what computer i connect them to.

The reason this topic is highly technical is because i always get the same (just replace it answer)

so one out there has to know how to repair monitors.. and like i said the picture is fine its just they turn off after awhile..

 

[capybara]

ive seen this before, there was a small crack is the soldering connection of the wires (to the power supply?) which expanded with heat and time

 

[GprophetB]

I have a 21 inch monitor that doesnt exactly shut off but it flickers on the left and right side. It also bends and curves on left and right sides, as for color it seems fine.

I have a feeling the tube would have to be opened and re vacuumed, which i cannot do

i hope not though, anyone have an idea?

 

[Mday]

this isnt tech support.

but i'll give you some info:
you'll need the manual for the crt, the full maintenance manual which you dont have\cant get and a multi-meter to test voltages, currents and capacitances.

it'll cost you a fw hundred or dozen man hours sinc eyou have no experience. how much is your time worth?

 

[nineball9]

Shutdown problems - check shutdown circuits. Power supply and high voltage circuits will have them and probably others too. Sometimes caused by a thermal intermitant such as cold solder joint, faulty connector, or a cracked circuit board trace.

Flickers and bending on sides of display - deflection circuits. Check pincushion, high voltage, possibly low voltage circuits. Scope would be helpful to diagnose, though simple voltage readings on the yoke might be a starting point.

For either problem, a schematic is a definite plus, if not a requirement. Monitor schematics are difficult, if not impossible to obtain.

Knowledge of electronics and repair-troubleshooting procedures kind of helps too!

 

[0roo0roo]

i have the same problem, but monitors are so cheap now,.....not worth it.

 

[capybara]

i hope you know about the high voltage wire with thick back insulation that goes to
the back of the picture tube. dont touch it. dont go near it.

 

[beyoku]

yes dont touch it for a while - day or two after you unplug it - it is powerful enough to kill you ! My dad got shocked very hard i saw his body crumble and cringe up - he is fine and we laughed after. but be sure to wait before you touch

 

[IamElectro]

Originally posted by: beyoku
yes dont touch it for a while - day or two after you unplug it - it is powerful enough to kill you ! My dad got shocked very hard i saw his body crumble and cringe up - he is fine and we laughed after. but be sure to wait before you touch

This would be incorrect.

TV and CRT monitors can hold high voltages in thier Flyback transformers for years with out discharging.
The flyback transformer attaches a wire to the side of the CRT with someting that looks similar to a suction cup.
If you are unfamilar with these types of electronics I would avoid them as it could cause serious injury.

 

[User1001]

Originally posted by: IamElectro

Originally posted by: beyoku
yes dont touch it for a while - day or two after you unplug it - it is powerful enough to kill you ! My dad got shocked very hard i saw his body crumble and cringe up - he is fine and we laughed after. but be sure to wait before you touch

This would be incorrect.

TV and CRT monitors can hold high voltages in thier Flyback transformers for years with out discharging.
The flyback transformer attaches a wire to the side of the CRT with someting that looks similar to a suction cup.
If you are unfamilar with these types of electronics I would avoid them as it could cause serious injury.

Extremely true. And definately wear anti-static bands. You don't want to set of the high voltage wire like that.

 

[nineball9]

I've been repairing TV's as a hobby for over 30 years, but I've never seen one that held a charge for years! The aquadag is grounded, and the high voltage anode connector is fairly well insulated. Older sets used large caps in their power supplies, but these usually had a bleeder resistor across them. I usually jumpered these anyway before troubleshooting a set, though I pegged a few analog meters over the years. Newer sets with switched power supplies don't usually have these large caps. The HV - horiz output - voltage doubler/tripler circuits don't stay charged very long either. The CRT acts as a cap, but it too discharges fairly fast. Naturally, safety first is a very good idea!

An antistatic wrist strap provides a high impedance path from one's body to earth ground. It dissipates static electricity build up in one's body to prevent damaging low-voltage sensitive semiconductors. It's not used to prevent getting shocked from charged circuits.

 

[Red Squirrel]

Actually, if you were to get shocked with a ground on you, the shock would be worse as the electricity would want to go through your body and to the ground.

I heard a monitor has enough power to kill someone 3 times. It only takes once.

But stay clear of the capacitors/circuits and you should be fine. (by capacitors I also mean the top of them, the metal on top can carry a charge, I learned that the fun way with a PSU)