A 1920 ZONOPHONE ‘HORNLESS’ GRAMOPHONE.
PLEASE NOTE: this is NOT a tutorial on how to overhaul an old gramophone; it is merely to show you what they look like inside. Stripping down a gramophone requires a definite procedure for safety’s sake – that is, safety for YOU as well as avoiding damage to the machine!
This Zonophone machine dates from 1919/20. It was called the ‘Model 2’. We bought it at auction for £50 in about 2009. This was about the right price – neither cheap nor dear. Of course, we had made sure the motor ran more or less OK during the viewing before the auction, though we had not heard it in action. That is not usually possible at an auction.
But the outward appearance was very good, as you can see, for a 90-year-old machine.
When we got it home, we tried it out. It did play records quite well, but there were a couple of problems that needed sorting. So we had to dismantle it to clean up the motor. The images we took while doing this will be just the job to show you what an old gramophone is like inside. Though they may look very different, most spring-driven gramophones are are based on the same general plan.
The top (this is called the motor board) has been removed.
Here is the underside of the motor board with its motor. It has two springs: these are located in the round drums. They go in opposite directions, so that when you wind up the machine, the torque (energy) is equally shared between the two springs. The arm that goes through the hole connects with the speed control lever.
The winding handle screws into this main shaft. A ratchet & pawl prevent the shaft from rotating backwards when you release the handle. Later, a spiral spring, very close-fitted around the shaft, served the same purpose. When you wound the handle, the spring tended to ‘uncoil’ & the shaft could turn. But when you stopped winding and the shaft tried to go backwards, it merely drew the spring tightly around itself, and so was held still. This was a far simpler, cheaper & smoother system, and worked just as well.
Here, the motor is upside down. The power from the springs is exerted by the big gear A. This drives the worm on Main Shaft B, which goes through the motor board, and the turntable fits onto the end of it. The gear C on the main shaft drives the three-ball governor via another worm drive D. As the governor rotates, the balls are driven outwards by centrifugal force, and their mounting springs are bowed; this draws the round brass disc inwards. Its travel is limited by the leather pad E, and thus, the speed of the motor is fixed. The leather pad needs to be well soaked in oil, so the disc can rotate freely while in contact with it. Often, there are two such pads, one each side of the disc.
AFTER LETTING THE MOTOR WIND COMPLETELY DOWN, we dismantled it. As you can see, it’s not very complicated. The main shaft & the governor were left in place; the adjustment of the governor is very delicate, and well-designed motors always allow cleaning to be made without disturbing the governor. It’s easy to clean around it.
The main shaft & governor have now been cleaned, an easy (if messy) job.
However, the spring drums were caked in solidified ‘graphite grease’. Remember, 100 years ago, they didn’t have all the versatile lubricants we have today! They used simple grease, mixed with fine graphite powder. The springs inside the drums were also covered with this. It worked very well; but after many years, it would solidify & become ‘sticky’ – which is the opposite of a lubricant! The spring drums could not contra-rotate properly; they would go in jumps. Worse, the springs inside could not unwind evenly – they would ‘jump’ too, sometimes with great violence, shaking the whole machine, perhaps even damaging the record, as the sound box leaped up & down. That was the main reason we dismantled this machine; it was ‘bumping’, though not very badly. (We thought that the previous owner was very good at conserving wood, as the box was so tidy; but not so much into mechanical things…)
The spring drums are now clean on the outside. But what about the inside? Sorry to keep banging on about safety, BUT DO NOT, ON ANY ACCOUNT, OPEN A SPRING DRUM AND TRY TO REMOVE THE SPRING TO CLEAN IT. PEOPLE HAVE BEEN BLINDED AND EVEN DIED BY HAVING THEIR THROATS CUT, BY A FOURTEEN FOOT LONG SPRING THRASHING OUT OF A 4 INCH DRUM!! All we did was to spray WD40 into the centre holes a number of times & leave the drums soaking overnight in a bowl of petrol or paraffin – which is also not without its hazards, so leave it outside well away from the house! – and the grease will be loosened. After drying, lubricating oil can be introduced into the drums gradually, through the centre.
Here is the reassembled motor, looking very dry to be sure; but the spring drums were already well loaded inside with oil, and after lubricating all the other moving parts, the machine was put back together. One last important thing had to be done.
The sound-box was original, but the rubber gasket tubing had gone hard/perished/shrunk, so the diaphragm was not supported properly & the sound was thin & ‘whiny’. New tubular gasket rubbers were fitted, one each side of the mica diaphragm. After completely cycling the springs 20 or 30 times over a few days, it will now cheerfully play two 12″ records at one winding, and even three 10″ sides if the third one is not too loud!