Hello, I've been working on a Star Trek machine, and I'm stuck. First, there was a problem with the X-Y deflection board, in the power input section. The main fuses kept blowing and there was no deflection chatter. I replaced a transistor and a zener diode that were bad, and now that seems to be working fine. The chatter sounds normal and the fuses don't blow. There is still no picture, however, or heater glow. I have checked the voltages on the 10-pin connector on the HV unit, and all are normal, EXCEPT pin 7 (+6.3VAC for heater -- reads less than a volt) and pin 10 (~400VDC for focus and brightness -- reads less than a volt). I don't have a HV probe, but when I attempted to discharge the 22KV from under the anode cup, nothing happened (usually there are a couple of snaps when I touch the scredriver to the metal housing) I swapped HV cages with a spare (untested) one and I got the exact same indications. The tube came from another broken Star Trek I bought (so
now I have two broken ones, plus a third monitor board set for parts), so it has never been tested. But a bad tube should still have the 22KV at the anode, shouldn't it? So I don't suspect the tube. And even though the HV cages were also untested, the likelihood of both of them being defective in the same way seems low, so I don't suspect the HV unit. Is my logic flawed, and I SHOULD suspect the HV unit or the tube? Or is there a potential fault somewhere else that I'm overlooking? I have pored over the G08 monitor schematics in the ST manual, and Mark Jenison's G08 Vector Monitor Guide (aka FAQ v.1.0), and of course I searched the vectorlist but couldn't find these particular symptoms. Any ideas??? PS I was supposed to have the machine fixed be Christmas!! It was for my wife!! PPS Happy Holidays!!!
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Received on Tue Dec 27 14:32:41 2005
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