My CRT Display Isn't Working

Rybett Controls WebDoc 109   (Copyright 2008)   Return to [Index]

CRT (cathode ray television tube) displays are used by many Rybett BTR products and most PC computers. When a BTR or computer stops working, the display may hold clues to the problem and cure.


Most desktop and mini-tower PC computers contain a CPU motherboard and daughter cards for disk I/O and video functions. The CRT display plugs into the video adapter card to receive its sync and color signals. There are 4 types of CRT displays common in shops:

TTL uses a Hercules adapter, displays mono text & simple graphics and uses a 9 pin plug.
EGA Color uses an EGA adapter, displays 400x350 color graphics and uses a 9 pin plug.
VGA Mono uses a VGA (1/4MB) adapter, displays 640x480 and uses a 15 pin plug.
VGA Color  uses a VGA (1MB+) adapter, displays >640x480 and uses a 15 pin plug.

When trouble shooting displays, it is easy to exchange monitors and video cards with other computers. However, in the list above, only VGA Mono and Color are interchangeable. Make sure adapter cards and all plugs are well seated. If your display is working but has a wavy look, perhaps you are too close to a motor or other magnetic device.


Exec 1501 uses a 9" mono with AX131 composite bolted onto CRT wall.
Exec 1501 uses a 9" mono with AX141 TTL sync plugged onto CRT base.
Camstore 1 uses a 9" mono with AX141 TTL sync plugged onto CRT base.
Camstore 1SX uses a 9" VGA with standard PC type VGA adapter card.

Most CRT displays have a horizontal video driver card with small pots for adjusting size, brightness, vertical and horizontal sync just like your TV set. Many minor problems can be corrected by turning pots and wiggling connectors to clean contacts and adjust settings.

If you are adventuresome, the video driver card may be removed and the connector pins and transformer joints resoldered to repair tiny fractures that may appear with age. Would this qualify as a medical facelift? BEFORE WORKING ON A CRT DISPLAY, TURN OFF POWER. ALWAYS STAY AWAY FROM THE FLYBACK TRANSFORMER OUTPUT WIRE TO AVOID SHOCK. THE FLYBACK TRANSFORMER LOOKS LIKE A BLACK OR RED RUBBER CASTLE.

When returning a CRT product for repair, be sure to ship it properly with 3 inches of packing material on all sides.