Denford Software & Machines

Hi Im new here.I have a 1986 triac SERIAL # EO 2654/1. It was working great but now the crt and monitor doesn't display anything. I have checked the 12v power and cable from PLV going to the KME MB12 board and thats good. Also have done self diagnostic tests. I get no response on the X test on either monitor but get results on G test a and b on the ext. monitor. I get the flashing square and the square with circle and cross hairs. I am confused why i get results only on ext. monitor I thought they would both recieve the same signal as when it was working they displayed the same info. I have the manual and schematics. If anyone can advise me I would greatly appreciate it. Thanks. Main circuit board is Issue 2.

Hi,
The vdu signal to the crt & the external monitor is derived from 2 different circuits & is switched when the tool path graphics are selected. This is why the external monitor works in some modes. If you are familiar with electronics I can help you find the fault. I know the Triac very well as I worked for the company who built them.