Osborne OCC1 problem

There is a de-facto 'standard' for 10 pin monitors (using a 0/156" pitch edge connector or header plug). The DEC VT100 monitor PCB is one such, if you need more details... A more accurate fault description would be helpful... Correct. Taht implies a digital prolem, and not necessarily in the video circuitry.... Does this machine use a 6845 or similar for hre video timing chain? If so, mis-programming that will cause apparent sync problems. So the fault could bever well be proscessor, ROM, or bus related. That's why I'd start by looking at the horizotnal sync pulses when you have the lines and when you have a good display (even if the machine has crashed). If they're the same timing, then the fault is monotor (or PSU?) releated. If not, then the video timing circuitry is palying up _or being mis-configured by software_ Sony were sometimes kind enough to label connector pins, supply lines, CRT pinouts, etc in the slikscreen, few other manufacturers were. If it is a standard pinout, then the connections are 1 Ground 2 One end of the contrast control 3 t'other end of the contrast control 4 Slider of the contrast control 5 ground 6 Hsync 7 +12V power input 8 video input 9 Vsync 10 ground Depends on what you're working on, and the design of the monitor. The PCB-mounted capacitors will normally discharge fairly fast (minute at most), so there'll be no masty votlages on PCB tracks or CRT _pins_ after that. The EHT, stored in the 'capacitor' of the CRT glass can stay for days, but (a) it'll be discharrged by the beam current in any normal monitor (so this is really only a concern if the screen is totally blank), () the only way you'll get in contact with it is if you remove the anonde connector and (c) good monitors have a bleeder resistor, often inside the flyback trasnformer. If I am going to be removing the EHT connector, I check the residual voltage with an EHT voltmeter (which also happens to discharge it :-)). Otherwise, I don't worry. So far I've never had a shock doing that. -tony