DEC VT101

I thought the VT101 video board was the same as the one in the VT100, so the VT100 pritset might be of use. But... There are at least 3 different VT100 video boards that I've seen, there may be otehrs. I've not seen them all in the printsets. So even with the printset you may not have the information you need. Msot of the time, problems on the VT10x video boards are in the horizotnal output area. The flyback transformer -- separately moutned on the chassis -- fails, and often takes out the horizontal output transistor. Im any case, findign a flyback transformer is not easy. AS with all small mono monuitors there's a bt you can do without a schematic. First see if the CRT heater is glowing. It runs off the 12V line, so if it's out eitherh the eater is open :-(, the 12V line is misisng, or there's a simple fault on the PCB. Sometimes (and I cna't rememebr if the VT10x is like this) there's a picofuse in series with the supply. A failed horizontal output stage can blow that, removign power fro tmeh entire monitor section. If you have an EHT meter, measure the fianl anode votlage. Expect about 12kV. Measure the CRT pin voltages, even if you can't check the final anode votlage. The pinout is the normal one : 1 : control grid 2 : cthode 3 : heater 4 : haaterr 5 : control grid 6 : first anode 7 : focus anode. Expect a few hundred votlas on the 2 anodes. One of pins 3,4 is likely to be groudned, expect about 11.5V on the other one. A few10's of votls on the cathode. THat should give you an idea of whether all the high votlges are misisng (hoizontal outptu trouble), jsut oen is misisng (rectifier/capacitor problems of that supply most likely) or withehr the CRT is biased well beyond cut-off (grid very -ve wrt cathode). -tony