20-10-2015, 04:34 PM
I started with the output valve and there was nothing there. I did find the grid stopper resistor too and found that was a touch out of spec in Ohms. Anyway the starting point was no voltage on the valves.
Transformer is O.K. Tube heater circuit is O.K. Scale lamps look as if they kicked the bucket 20 years ago! They're six volts but the feed wires are fine and do measure 6 volts.
Rectifier it seems must be working as voltage will be D.C. from cathode to H.T. Smoothing cap. And at the cap on one lug there is voltage measured in D.C. There is, however, no voltage from this can on the opposite lug where an HT supply wire leads to the next smoothing can. There are actually 2 HT cans and not just the usual one. And no voltage anywhere on the other can where more wires radiate to the circuit.
Continuity is O.K., though. It's just voltage is not reaching those wires. There is a bit of rust on the top of the cans so maybe damp and cold over the years has had its impact.
I'll be working on it a bit more tonight...
Transformer is O.K. Tube heater circuit is O.K. Scale lamps look as if they kicked the bucket 20 years ago! They're six volts but the feed wires are fine and do measure 6 volts.
Rectifier it seems must be working as voltage will be D.C. from cathode to H.T. Smoothing cap. And at the cap on one lug there is voltage measured in D.C. There is, however, no voltage from this can on the opposite lug where an HT supply wire leads to the next smoothing can. There are actually 2 HT cans and not just the usual one. And no voltage anywhere on the other can where more wires radiate to the circuit.
Continuity is O.K., though. It's just voltage is not reaching those wires. There is a bit of rust on the top of the cans so maybe damp and cold over the years has had its impact.
I'll be working on it a bit more tonight...
