Computer monitors
A guide to problems with older computer monitors -drafted 2005.
My monitor is not working
My monitor has a poor display
My monitor flickers.
My monitor is not working
Is the signal cable connected to the computer?
Is the computer on?
Has it been set to go into hibernation if left for a while? (hit the space bar on your keyboard).
If your computer has multiple video cards, is this one activated?
Did you know that if your computer has TV-out, the TV port counts as a second monitor?
My monitor has a poor display:
Try adjusting the display – usually there are buttons on the front that bring up an on-screen menu, where (on CRT monitors) you can adjust many parameters controlling the brightness, contrast, position, size and shape of the display, and usually the colour balance.
On your computer you can adjust display settings, mostly to do with the resolution and the number of colours. Be careful here, as it may be possible to set the computer to deliver something that the monitor cannot handle, or even damage the monitor.
If the display looks bad with the relevant shape control set to near mid-position (50%), it could be that there is an internal fault.
Did you know that with TV- out video cards there are some restrictions on what refresh rate you can set, and on which screen has the full motion video on it?
My monitor flickers…
All CRT monitors flicker at the frame rate. If you are one of the unfortunate individuals who can perceive this, try increasing the frame refresh rate by one or two steps in the computer’s Display settings, e.g. From 60 to 70 Hz. Don’t overcook it by setting a rate that the monitor can’t handle.
Intermittent faults
A lot of CRT monitors have little peculiarities like a twitch or roll every few days that never happens when the monitor technician is looking. I advise you to ignore this behaviour until it turns into a real fault – which it probably won’t.
Troubleshooting a faulty monitor:
Eliminate external causes, as above. Never open up a computer monitor unless you are a monitor technician. CRT monitors contain a variety of lethal voltages, and even if you think you know which bits not to touch, other people may not be so smart.
Don\’t assume that the most impressive faults are the hardest to fix, or that minor faults are going to be cheap to put right. If the monitor is completely dead, it could be worth getting a technician to look at it, as it might be a simple fault such as a tired fuse, shorted diode or a bad joint, or it might not! If there is an intermittent fault of the kind that responds to a slap on the side, it may be completely repairable, if the technician can find the fault location!
In general, though, it will not be worth spending much on repairing a typical 17″ CRT monitor, as the value of a used, working CRT monitor is now quite low.
Flat panel TFT monitor faults:
Flat screen monitor faults fall into two or three areas
It’s dead – power supply related.
The display is dim or invisible – backlight fault.
The display breaks up either immediately or after warm up – digital fault.
Bad pixels.
The prognosis for getting one flat panel monitor repaired at a small repair shop is not good. Potentially, power or backlight faults are repairable if the technician can effect a minor repair or get spares, but digital faults are more difficult.
Most TFT monitors contain a small number of bad pixels (manufacturing defects).
Use due caution when buying a used flat panel monitor. One of the commoner problems with a flat-panel monitor that appears to work when switched on is that it will start to misbehave with a digital fault within an hour or two, after it has thoroughly warmed up.