CRT repair and troubleshooting



This page is dedicated to the repair and troubleshooting of CRT (cathode ray tube) televisions, monitors, and other equipment.

Safety Warning:
CRT displays contain extremely high voltage (up to 30,000v!) and the acts as a capacitor which can store a lethal charge for weeks after the display has been unplugged. The tube  MUST  be discharged properly before performing any kind of internal repairs.

Here is a good guide to refer to for discharging CRTs: https://www.youtube.com/watch?v=1CVXzlkOjGg

CRTs also contain mains voltage so general electrical safety precautions should be taken when working on them.

Service Manuals:
Due to the facts that most CRTs come from a time when repair was more common and companies didn't claim it was a security risk to have someone replace a failed capacitor, complete service manuals that included full schematics were often given out to independent repair shops, in the cases of older televisions they may have even been included with the television. Many of these manuals and schematics are now available online, simply look up the model of your TV/monitor and look for a service manual.

Descriptions and service manuals for Commodore monitors can be found here: Commodore monitors

Picture adjustment
NOTE: Most picture adjustments should only be done after it has been confirmed that there are no faulty components on the board and those that are have been replaced.

WARNING: For most of these adjustments to be effective, they must be performed while the CRT is turned on, make sure that you are isolated from ground and are using a nonconductive screwdriver to make adjustments. Stay clear of the neck board, anode cap, and exposed flyback circuitry whenever possible!

Over time, CRTs can go out of focus, misconverge, dim, or develop geometry issues; here is a very basic guide to troubleshooting and fixing such issues:

To start you are going to want a good testing image or program that can display images onto the CRT screen to aid you in adjusting focus or geometry. Here are some ways to do that:


 * NEC test pattern generator is a program that will run on Windows and Linux (using Wine) and will generate test images onto your monitor for convergence, geometry, focus, and more.
 * You can buy or make dedicated hardware that plugs into TVs or monitors and generates test patterns on the screen.
 * You could burn a video calibration disc and play that onto the TV through a game console or DVD player. (Here is an example of one for NTSC TVs: https://archive.org/details/AvCalibrationNtscDvd)
 * Some TVs or monitors may contain built-in test patterns that can be accessed through a service menu, check a service manual to see if they exist for your model and how to access them.

Specific Models
Repair guides for specific models of television or monitor.