[R-390] R-390 revival woes...

[Roger Ruszkowski]

Terry,
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Question: Is there a convenient test point anywhere on this rig to accurately measure the 6.3VAC filament rail voltage? 
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Not really.
Just pull one of the tubes on an R390/A and measure the 6.3 on the tube socket.
Look at the schematic and see what you are getting.
Remember the R390 is 24 volts with 4 tube strings and you need to pick your point.

If the 26Z5s have been solid stated the filament wire were likely cut off the tube socket. But you can wire the filament windings back to the tube sockets but not to the B+ cathode pin so you have a place to measure the voltage. I do not know why the filament voltage was hacked out of so many of the power supplies when the diodes were installed.


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Panel lights seem a little dim compared to my EAC 390A.
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R390 dial lights are not as bright as R390/A lamps.

R390 lamps are 28 volts on a 25 volt circuit.
Several (Ok a couple) different lamps are available. Different manufactures also have different lumens for the same part number.
The lamp is in range of acceptable type values. The lamp may pull a bit less current to give it a longer life span.

There are also red, blue and other color lamps plus  Long life lamps.

Roger AI4NI