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Philco 680 Shadograph.
vaguy22
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#1

02-02-2018, 10:50 PM
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
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Nathan Slingerland
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#2

02-02-2018, 10:56 PM
Any chance that the bar magnet has become demagnetized?

500 ohms sounds low to me for the coil resistance - typically they're >1K.
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morzh
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#3

02-02-2018, 11:14 PM
Even if 500 ohm, still should react.
I second the magnet thought.
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Radioroslyn
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#4

02-03-2018, 10:08 AM
Just for grins take a 9v battery - to the chassis and + to the grid cap of the 85. Should cause the vane to deflect.
When my pals were reading comic books
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workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
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vaguy22
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#5

02-06-2018, 10:26 PM
Thank you folks for the hints. Norman
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