Troubleshooting guide

Cinematronics Vector Monitor Repair Guide v.1.0
Page 40 of 53
Symptom: Vectors do not line up straight. Vectors at the screen edge are bigger.
It is unlikely the DACs are bad. Things are drawn pretty dramatically wrong, when they go.
• Start by adjusting the line length pots on the monitor – R102 and R202.
• Check the feed back diodes on the monitor (near the TL081).
• Step through the edge-gain amplifier section of the monitor looking for bad components.
Symptom: Strange graphics when my ship moves horizontally. The space between the vectors
that represents the ships expands and contracts vertically as it moves across the screen
horizontally.
Try swapping the two DACs and see if the problem moves to the other axis. Replace the DACs as
necessary. Also suspect the Analog Switch IC1. This problem can best be checked with a scope.
Symptom: No brightness control.
• Check intensity pot R11 for open wiper or internal short.
• Check for bad solder connections to R11.
• Check C17. Note: the only Cinematronics manual that shows C17 is Rip Off. All the other
manuals list C17 as a possible cause in the troubleshooting section, but they do not show the
capacitor on any of the schematics. Although the Rip Off manual shows C17 as a 10uF 150V
cap tied to one of the three terminals on the brightness pot on the monitor board diagram, the
capacitor is not on the schematics.
Symptom: Monitor is extremely bright; no focus. Retrace lines are visible.
Although a very rare occurrence, you might have a heater to cathode short in the picture tube. If
you can find one, a CRT isolation transformer will fix that. A heater-cathode short like this will
take the brightness to supernova levels! You will be unable to reduce the brightness to a usable
level.
Symptom: No high voltage. CCPU board is known good. Power Supply tests good.
• Connect an oscilloscope to the yellow wire leading to the CRT connector. Set the brightness
full clockwise. When viewing your scope, there should be an 80 to 100 volt DC base with