[vaguy22]

Has anyone fixed a Model 680  shadowgraph. I tried the usual hints from the " repair bench" with no results. the vane is free and coil shows 500 ohms resistance. #85 tube is good with 70 volts plate voltage. Thanks in advance   Norman

[Nathan Slingerland]

Any chance that the bar magnet has become demagnetized?

500 ohms sounds low to me for the coil resistance - typically they're >1K.

[morzh]

Even if 500 ohm, still should react.
I second the magnet thought.

[Radioroslyn]

Just for grins take a 9v battery - to the chassis and + to the grid cap of the 85. Should cause the vane to deflect.

[vaguy22]

Thank you folks for the hints. Norman