Thursday, April 10, 2014

Parvus Mechanism

The complete mechanism of the Parlophone Parvus portable gramophone is again mounted on the deck. Newly painted the deck and all parts polished and fitted again. The whole assembly dropped back in the case and fixed with 12 screws all around.

The side-view of the bare deck assembly nicely shows how the motor is in one part of the case and the whole acoustic part in the other half of the box. The tone-arm connects to a fairly basic and short horn. That horn projects against the divider plank in the box to project the sound backwards (and somehow out of the opening in the deck of the gramophone). It also shows the how thin the sheet-metal deck really is. Flimsy even.

The Odeon motor looked fine as it was. Didn't spot a type number, but it does have the Odeon logo, Odeon also being part of the Lindström group of companies. Luckily the spring seems to be fine, locked in a closed drum. Even though the grease in the motor is old and will be a bit hard, a full winding still plays a 12" record. So I'll not be taking this motor apart quite yet, certainly not messing with the spring drum for now.

The friction pad of the regulator was hard like a stone and quickly replaced by a small square of leather cut from an old belt. This pad is held in a U-bend that is easily pried open and bent closed again with pliers. After fitting the new pad, apply liberal amount of machine oil. (When first spinning the motor again, be aware that the friction disk is going to spin around some excess oil as the pad touches it...)

This motor has a very handy speed adjustment lever arrangement, located around the spindle. Calibrating this motor to play at 78 with the lever in the centre position is relatively easy. After setting the motor to 78 with the lever, loosening the clamping screw that locks the lever to the adjustment bush allows you to easily move the lever to the middle position of the scale. Very visible technology. (On the HMV portable this adjustment is much more of a trial and error process.)

Originally the motor was mounted with rubber washers, pulled up against the deck. These had turned to crumbly stone and a set of hex nuts now act as spacers. The way the rubber was mounted with the motor still pulled it metal on metal, I can't yet figure out why rubber was used at all. It cannot have been very useful in damping the motor sound transmitting via the deck. Maybe I will fit new proper rubber washers one day and figure it out.

The semi-automatic brake took some tweaking to make work again. The position of the brake rubber relative to the turntable inner rim is the critical alignment. When off, it should run clear of the rim always, but when the brake is engaged it must press with enough force to hold the turntable against a fully wound motor without slipping.

Ergo the Parvus is getting there. The soundbox is next to be tackled, but the gramophone already looks quite good and it even plays again!


  1. Wait a minute... That's the same machine? Not something you bought in a store recently? Great work!!

    1. :-D
      Ha, yes. (Tnx.) A lick of paint does wonders - and luckily most plating was fine underneath only some superficial corrosion. (Well, several coats of paint and sanding to be honest. And did light nickel-plating on some screwheads ;)

  2. Beautiful restoration, you put some excellent time in and it shows.