Backspace does not erase: Tune-up for the wind-up gramophone (and playing records)

Spending some time last weekend playing records, the bright colors of some labels do impress. From the way these were stored, they'll have been shielded from sunlight. Sleeves are usually a bit faded, yet these orange labels really stand out.

The records from the 20s and 30s found here in the low countries are quite international. Much is relatively local, German, British and French, but this Crown is a US record and e.g. the Odeon is from Argentina.

The sleeves make a point of the music having been electrically recorded. This was something new that quickly became the standard from the late 1920s.

And also the below Dutch record sleeve proclaims; "The latest invention is the Homocord Electro - the electrically recorded disk".

Electrical recording really did improve the quality of the sound. Playback was still mostly without electrical pick-up (that started emerging in the late 1930s for (expensive!) home equipment). These ~1930 records would've been expected to be used with an acoustic reproducer. For example on a portable wind-up gramophone, like this 1929 HMV model 101.

During playback however, some louder sections of the record suddenly sounded 'off'. The gramophone was not keeping speed. As it had been a while since servicing, very likely then that the motor badly needed a tune-up. Maybe even a re-greasing of the motor spring.

To do a service: slide off the circlip, switch the brake to 'off' and lift off the turntable. Give the motor time to fully unwind - when servicing a wind-up motor there should be no tension left in the spring. After removing the four screws in the corners of the motor board this can be lifted out, front up first and sliding the motor 'block' from under the rear deck and forward.

This time the motor was kept on the board; the whole board was placed upside-down on the rims of a baking-tray with a towel for protection. Removing three small screws allows the motor cover to be taken off. Then another three larger screws out of the pillars allows the motor plate to be taken off.

Again; take care to not loose the small bearing-ball under the main turntable-shaft (likely held firm in its grease, but still). Also note the washer between the arbor-shaft and bottom-plate - it will have stuck to either the motor or the plate.

The gears were very 'gummed up'; the brass of the intermediate gear had turned green and the teeth filled with 'gunk'. Slowly growing corrosion in the gears mixed with grease could also make a motor lose power - and of course the governor was in dire need of fresh oil on the friction pad. Seeing these issues, decided to leave the spring itself alone - its greasing of ~10 years ago likely still good enough.

The gears were all cleaned, stubborn dirt removed with wooden tools (not scratching). New grease with this time also some graphite applied to the gears.

The pressure angles of the gears driving the governor are really steep; will need good lubrication. For speed control the governor's friction pad and disk need to be well oiled - and the sleeve-with-disk that is moved by the three weights should move on the shaft without friction for proper speed-keeping.

The motor and gramophone put together again, it seemed to run just a little bit smoother. With 50Hz incandescent lamps becoming rare, strobe disks are getting more of a hassle to use for adjusting the speed. Today however a small application transforms a smartphone into a modern instantaneous speed tester. Nifty!