The 1950 monitor was actually produced by a company called AOC. Parts may still be available direct (although there have been conflicting reports). The AOC model of the monitor was known as the AOC CM314. The tube is made by Hitachi.
Common Problems
A sync problem may be caused by the monitor detecting sync on the Green input and then disabling the horizontal and vertical sync inputs. Removing the 10K R854 resistor or the 10uf C812 capacitor on the small vertical board may fix this. It may also cause problems of its own, so be warned.
The analog/TTL switch appears to be prone to failure. However, if switching the switch brings back the picture, it may actually be that the 74LS123 (IC805) on the same board is failing. The suggested course of action is to replace (or at least resolder) this chip first, since it's a commonly available part.
A defect in the way the 74LS123 is mounted may be present; there should be +5V on pin 3, but the way the chip is mounted or the board is manufactured, it may be intermittent. There should be a PCB trace between pin 3 and pin 16, however, pin 3 is not soldered to this trace, but only friction-fit (non-plated-through holes?). When the analog switch is moved, it causes intermittent contact between pin 3 and the trace. A soldered jumper to pin 16 is an easy way to fix this, or you may be able to solder to the trace already present.
Another common problem is the failure of a multifunction sync chip. Replacements should be available from Sony. The Toronto ABUG user group confirms that this chip is available from Sony Canada, on Gordon Baker Road (presumably also in Toronto, although they don't say).
The high-voltage boards may crack; this can be one cause of the monitor that starts working when you hit it.
A 1 megohm resistor in the second power supply's startup circuit goes bad, causing the monitor to remain dark. Replacing the resistor with a higher wattage one may help prevent the problem in the future.
Manufacturer
AOC International
311 Sinclair Frontage Road
Milpitas CA 95035
(408) 956-1070
Specifications
Sync Frequency: 15 kHz to 35 kHz Horizontal
50 Hz to 80 Hz Vertical
Dot Pitch: 0.31 mm
Input Connectors: One permanently attached HDD15 (AOC CM314 also
has an attached DB9
for digital RGB.)
Pin-Outs (HDD15)
Pin 1: Red
Pin 2: Green
Pin 3: Blue
Pin 4: Unused
Pin 5: Test
Pin 6: Ground
Pin 7: Ground
Pin 8: Ground
Pin 9: Unused
Pin 10: Ground
Pin 11: Ground
Pin 12: Unused
Pin 13: Horizontal Sync
Pin 14: Vertical Sync
Pin 15: Unused