Volmar DOM Record Player

[Michael Maurice]

I've was asked to restore this record player.

It is fitted with a Garrard 210 record deck, see this thread

The machine is interesting because it an AC/DC machine.

It has 5 valves and is built on two circuit boards, one is the amplifier which uses a UY85 and UCL82, the other is an oscillator which uses a UCC85 and two UL84's.

There is a switch at the back to select AC or DC operation.

In AC mode, the motor is driven from the mains directly. In DC mode the oscillator is switched in. There is an extra control mounted on the inside for the oscilator frequency or speed control.

The restoration was relatively simple, changing some horrible black Hunt capacitors.

There was a wax capacitor across the inverter choke.

I then made a modification to the chassis and deck earthing arrangements.

The deck was originally connected to the chassis via an 1800pF capacitor but the pick up was connected directly across the volume pot with the earthy end connected to chassis.

As this is a 'live chassis' arrangement it meant that the pick up cartridge was directly connected to chassis.

The original mains cable was twin fig 8 with no means of determining polarity so there was a 50/50 chance of the pick up cartridge being connected to the live side of the mains.

I replaced the mains cable with modern double insulated twin cable, connected the deck chassis to one side of the pick up and connected it via a 0.1uf/1000V capacitor.

It worked beautifully though it was a bit hummy.

Here are some pictures

[Michael Maurice]

And some pictures of the insides, note the two PCB's and what looks like two transformers.

The 'transformer' at the back is the inverter choke.



One little problem when I returned it to its owner was that the autochanger didn't work correctly, a small circlip had come off one of the links, I fitted a new one to ensure it worked correctly.

[Nickthedentist]

Thanks for the update, Michael.

What a bizarre contraption. Presumably, they were only bought by people on DC mains, so they must have had a fairly limited market.

Has anyone else ever seen anything similar?

Nick.

[Darren-UK]

Someone else had/has one of these ridiculous contraptions.

Why they couldn't use a DC motor, with governor, and conventional AC/DC supply arrangements is a mystery.

[paulsherwin]

As you say, bizarre. I wonder why they didn't use a standard AC/DC motor, as used in sewing machines for 50 years?

[AC/HL]

The Ace RG354U was a radiogram with the same method of supplying AC to the motor. Used 2 x 50CD6 (R&TVS volume V)

[Mike Phelan]

A universal series-wound motor might have had problems controlling speed, even with a governor, as speed is very load-dependent.
There's also the problem with obtaining several different speeds.

I've never come across one of these, but it sure is an interesting device!

[Radio Wrangler]

So the standard advice for fixing a record player of "Stick your finger on the cartridge pins"
needs the addition of a check first that it isn't one of these...

David

[Michael Maurice]

To be fair, this is the first record player that I've come across with this situation.

Most if not all other brands took care to include isolating capacitors on AC/DC machines.

If of course we see another Volmar, then we should warn the member of this potential danger.

[julie_m]

The speed of a series-wound motor (which depends on voltage and load) is not so easily predictable as an induction motor (which depends mainly on frequency, unless insufficient power is being supplied for the load). The earliest battery portable tape recorders used clockwork tape transports, rather than battery motors, for this very reason.

Also, by producing AC, you can use a transformer to supply the LT instead of a dropper resistor (though that does not appear to have been done here).

It all still sounds like a bit of a gimmick to me, though. Surely the only people who were still on DC mains by the time this machine was made, would have been unlikely to be able to have afforded it?

[Tim]

It all still sounds like a bit of a gimmick to me, though. Surely the only people who were still on DC mains by the time this machine was made, would have been unlikely to be able to have afforded it?

On board ships etc.?

[julie_m]

I was thinking more in terms of people living in tied cottages; if they were supplied with power from a factory, coal mine, railway or other workplace with its own generating plant, rather than being fed from the Grid, it might well have been DC.