V-M Model 800 Changer Restoration

With help from some folks on the Antique Radio Forum, I identified this changer as a Voice of Music model 800.

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V-M model 800 record changer

It's a 78 RPM changer with an Astatic crystal cartridge. It was installed in a Detrola radio/phono as a replacement for the original turntable or changer. You can see where the front edge of the base plate was trimmed off to allow the changer to fit the cabinet. The cutting was done by drilling a number of small holes, and then either cold chiseling or hacksawing off the waste. The cut was finished by filing, but the holes wandered enough that it couldn't be finished to a smooth straight edge along the entire cut.

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Detrola chassis 448 with converter tube relocated to the rear

Even more effort went in to the electronic part of the modification. Whoever installed the changer had the problem that the changer mechanism interfered with the 12SA7 pentagrid converter tube. The installer's solution was to relocate the 12SA7 to the back edge of the radio chassis! It was a heroic effort.

Volume 17 of Riders Perpetual Trouble Shooter's Manual contains service data for the V-M model 800 changer. I hear that there is a Sams Photofact, too.

The first step in restoring the changer is to pull the turntable platter. The Riders was silent on how to perform this feat. I didn't see any C-clip or other fastener on the top, so I tried gentle persuasion from underneath the platter. There wasn't much access through the base plate, so I couldn't apply much force, and the turntable remained firmly attached.

I was told the Sams data said that the turntable was fit onto a taper surrounding the spindle, and that rotating the platter while holding the spindle steady should separate the turntable from the spindle assembly. This worked, but I had to apply a lot of force. 

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After removing the turntable, I saw that there were two drive dogs at the base of the taper that engaged a slot in the turntable. I had applied enough force to shear the dogs off the turntable lock - oops. I guess the right way to pull the turntable would have been to use two small pry bars under the edge of the turntable to lever it up and off the taper.

I'm planning to repair the the turntable lock by drilling holes where the dogs used to be and inserting a pair of large pins made from brass rod the same thickness as the dogs.

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The idler has a big divot in it, and the rubber has hardened, so it's off to Gary at V-M Audio Enthusiasts for a rebuild.

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The motor mounts are actually still soft and probably are still usable. This is a good thing, since Gary at V-M doesn't seem to have replacements.

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The motor mounts on a bracket that floats on top of the motor mounts, which are supported by flanged spacers held to the base plate with sheet metal screws.

March 17, 2018 Update

I finished this several years ago, but I’m behind in my blogging. 

Someone on the Antique Radio Forum pointed out that the idler has a removable tire, and suggested that I try replacing it with a rubber O-ring.

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I picked up a 3/16 thick by 2 1/8 inch diameter O-ring that matched the inner diameter of the old tire. However, Fred Longworth of Classic Audio Repair in San Diego pointed out that the contact area with the motor pulley and turntable rim and so may slip during the high torque required by the changing cycle and jam the mechanism.

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It turns out that the O-ring is too thick to clear the pivot post, so it was off to Gary at V-M Audio Enthusiasts for an idler rebuild after all. Meanwhile I started cleaning and relubricating the mechanism.

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I started by taking lots of photos of the mechanism, so I’d know how to put it back together.

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This is the sub-frame.

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The cam follower assumbly is the long rocker-arm and the associated rods.

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The is the ejector arm. The follower arm lifts the bottom end, and the other end pushes up the ejector slide.

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This is the control link for the reject mechanism.

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The trip crank assembly and the tone arm lifter.

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The control cam and switch.

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Another view of the tone arm lifter and the trip crank assembly.

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The sub-frame, cam, and cam follower.

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The ejector link and index spring.

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The follower arm spring.

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The cam, cam follower, and trip lever bracket.

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I started the disassembly by removing the trip lever bracket.

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Next I removed the screws for the sub-frame (spindle cam) assembly.

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Then I removed the screws for the fulcrum of the cam follower.

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This dropped the cam sub-frame and the follower arm assembly..

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The cam follower is on the end of the follower arm assembly. Once you’ve dropped the arm and the sub-frame, you can separate the cam follower from the cam.

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Then I removed the cam follower from the follower arm.

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Here’s a view of the cam and the follower guide.

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I removed the follower guide to clean up the cam and sub-frame.

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Here are the follower arm assembly, the trip link, trip plate, and ejector arm.

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The index and its slide stay attached.

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I disassembled the ejector and its trigger assembly ...

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… and removed the housing.

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I removed the trigger link.

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I disconnected the ejector link ...

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… and removed the ejector slide.

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I cut the wires to the motor to separate it from the rest of the changer and installed a pair of Molex connectors.

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I lubricated the cam and the cam follower with some synthetic grease.

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I reassembled the trip plate and control arm and the associated springs ...

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… and I reattached the index spring to the index ...

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… and to the ejector link.

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I reattached the control link.

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I greased the pickup crank and the lifter at the end of the follower arm.

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I lubricated the trip link crank and the end of the control arm with synthetic grease.

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I replaced the broken dogs by drilling a pair of holes into the turntable lock and glueing sections of brass tubing into them.

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The original flocking was in pretty good shape, but I managed to make a bug scrape in it. I’ve forgotten exactly how. At any rate, I needed to reflock the turntable.

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I built an electrostatic flocking gun using a high voltage negative ion generator from Electronics Goldmine. They are sold out of the one I used, but they have a more powerful one in stock.

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I cut the handle off of a stainless steel strainer using a Dremel cut-off wheel. Then I soldered a wire to it. I had to use silver solder and Tix flux with a butane torch to make the joint. I made the flocking cup from a polyethylene food container. I painted the inside with some Pliobond to give it some grip. 

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The strainer fits up against the inside lip. I used some electrical tape to hold it in place.

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I bought brown flocking from Donjer Products ...

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… and some “Undercoat Adhesive”. It looks like ordinary flat enamel paint to me.

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I covered a large cardboard box with a plastic bag to keep the flock confined.

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I coated the platter with the “Undercoat Adhesive”, clipped the ground wire to it, turned on the HV, and shook on the flock. It’s not perfect, but it turned out pretty good. I should have put a heavier coat of paint on it.

In this video, I manually cycle the changer mechanism.

And in this video, I cycle the mechanism under power.

The V-M 800 78 RPM changer is a nice straightforward mechanism and was fairly easy to clean, lubricate, and reassemble. It works well. 

© Steve Byan 2011-2016