Victor Sirius/9000 Monitor

It certainly sounds like a Sirius... Why do I bother? :-) I posted all the pinouts for this machine a couple of days ago, including the monitor connector. For refernce here's that one again... 1 : Video Output 2 : Ground 3 : +12V supply to monitor 4 : Ground 5 : Brightness cotnrol to monitor (the brightness and contrast are controlled by 3-bit 'DAC's driven from one of the 6522s) 6 : Chassis ground 7 : VSync 8 : Ground 9 : HSync A separate note in my diagrams says : 'VSync 75Hz, HSync 16.1KHz' Now, that 12V line comes from its own output in the PSU. It's regulated to 12V by the 7812 regulator A102 on the PSU PCB. It does however originate from the main chopper transformer, and since the other outputs seem to be present, the PSU must be running. Of course a blank screen can be caused by many other faults other than a loss of power to the monitor. I would start by disconencting the monitor and measuring the voltage on pin 3 of the monitor connector. If it's missing, check that regulator, and then trace back into the PSU circuitry (or ask me for more help). if it's there, then take the covers off the monitor. Plig the monitor into the machine and power up. See if the CRT heater is glowing. It runs off the 12V line via R901 (10 Ohm), which I don't think is likely to have failed. If the CRT heater is out, then either it has failed, or something in the monitor is crawign too much current and pulling the supply down. In my case there as a little interface PCB between the cable and the main PCB, the connections to the cable are : 1 (Whate) +12V 2 Kyeway 3 (Black) ground 4 (Red) HSYnc 5 (Blue) VSync 6 ( Inner of screened cable) Video 7 (Screen) ground. Check the 12V again with the monitor connected (e.g. at pin 1 of the cable connector inside the monitor). If it's low or missing, I'd suspect the horizotnal output transisotr (line output transistor over here), Q704. But if that's failed, something else might be the real cause. -tony