61 01 21 CG preamp repair

[electra225]

I have wanted to do research into the eye tube on Magnavox tuners. Both of mine are on all the time, regardless of the setting of the function switch. Seems like having the eye tube on when you are not listening to AM or FM is harder on an expensive 6E5 eye tube. Is that how they are supposed to work, or is there something wrong that should be investigated? Neither one of mine work terribly well as an eye tube, so that lends credence to maybe something being amiss somewhere.

[chazglenn3]

The S-600 in my CG runs 33 1/3 RPM slowly unless I run the platter at 78 RPM for a few minutes first. Then 33 is spot on. The workaround is okay for me for now. I'll have it properly serviced at some point.

[hermitcrab]

Maybe you could wire in a switch to kill the filament voltage to the tuner tube when not in use? not sure if the AVC signal goes thru the tube or the tube just monitors the AVC voltage... back in the day those eye tubes were in the billions , and they figured no big deal if you have to replace it...... now not so much , and they do wear out quick ... sunlight will absolutely destroy the phosphorus over time ..

[TC Chris]

Maybe you could wire in a switch to kill the filament voltage to the tuner tube when not in use? not sure if the AVC signal goes thru the tube or the tube just monitors the AVC voltage... back in the day those eye tubes were in the billions , and they figured no big deal if you have to replace it...... now not so much , and they do wear out quick ... sunlight will absolutely destroy the phosphorus over time ..

Or switch in a B+ resistor to reduce the voltage. I was going to suggest just switching the B+ off but it seems to me I read that some tubes don't like being run without B+.

Chris Campbell