01-28-2013, 03:55 PM
Hi! Fired the 84 up to check it out for voltages, & got mixed results.
The plate on the det./osc is 270---should be 240.
Plate on 2nd det. is 68---should be 70--close enough.
Grid 2 on det./osc is 127---service literature doesn't give voltage.
Grid2 on 2nd det. is 51---again no voltage given.
These voltages are from power supply neg.
Voltage from grid 3 to cathode is 23 volts on osc.
Variac is 115 volts in. The 42 output is apparently working--touching grid cap on 2nd detector gives loud 60 cycle
from speaker. Can't test the 77 on my B&K727, but I suspect a bad tube on the osc. Don't get any response
when touching the grid cap on the 77 det./ osc. Any ideas are welcome. Thanks. Jim
The plate on the det./osc is 270---should be 240.
Plate on 2nd det. is 68---should be 70--close enough.
Grid 2 on det./osc is 127---service literature doesn't give voltage.
Grid2 on 2nd det. is 51---again no voltage given.
These voltages are from power supply neg.
Voltage from grid 3 to cathode is 23 volts on osc.
Variac is 115 volts in. The 42 output is apparently working--touching grid cap on 2nd detector gives loud 60 cycle
from speaker. Can't test the 77 on my B&K727, but I suspect a bad tube on the osc. Don't get any response
when touching the grid cap on the 77 det./ osc. Any ideas are welcome. Thanks. Jim
