cuttercollector
Joined: 11 Jun 2006
Posts: 255
Location: San Jose, CA
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 Posted: Thu Jul 06, 2006 3:21 pm Post subject: G.I. deck |
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Hi. I am going on the assumption that this has one of the Astatic crystal cutters. It should have a pair of wires, and there should be another pair for the playback pickup. This cutter needs relativly high voltage by comparisson to a magnetic cutter, which can be driven off of any audio amp much like a speaker. The manufacturers used a special higher impedance tap on the output transformer of the tube amps these were used with. I think there is also a way to hook them directly through a coupling capacitor to the output of a tube. There was a sheet from Astatic that showed various possibilities. You might check West-Tech Services site to see if he has that spec. sheet on line. You can find him in the link section here. I once successsfully drove one of those cutters off the so called "70Volt" tap of a commercial PA amplifier. It provided about the right impedance match. As I recall, the Astatic wanted to see about 70V peak before "blowing up". If you are cautious and have a low power PA amp (like in the 10-30W range) you probably can try it, perhaps with the bass cut and trebble boosted a bit, slowly advancing the levels till you feel the stylus vibrate, after having set it up to cut a nice quiet unmodulated groove of proper depth. Then try a test cut, playing back simultaneously if you can. STOP advancing level if you hear any obvious distortion in the recording! You are at the limit. These were never meant to be driven by over a couple of watts, perhaps 10 peak at max., and do not cut to the levels on modern records. If you can't even feel the cutting stylus vibrate with just a little level from your amp, the crystal is probably shot. See West-Tech again for rebuild. Obviously you will also have to supply normal 110V to the motor of the turntable. Is it the manual type of deck that runs at 78/33 RPM used in the Meisners etc.? I have a couple of 78 only, older record changers with the recording arm, from some sort of console units. They will play a stack but only record 1 disc as the record head arm is not automatic. I never have built these into a base or tried to get their old creaky mechanisms working again.
Addendum :
I did go to his site and he has limited spec sheets here:
http://www.west-techservices.com/p13.htm
and pictures of both the G.I. decks, manual and automatic changer here:
http://www.west-techservices.com/p9.htm |
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