What could cause the slight speed undulations on my HMV 101?

[rasmus.baath]

Hi,

I've done a major overhaul of an HMV 101 portable. Took the motor apart completely, cleaned and oiled/greased all parts, even the spring. All cogs and bearings seemed to be in super condition and, now assembled, the motor runs really nice. Except for that there are very slight speed modulations when playing a record. These are very slight, making the record sound a little bit "out of tune", but they are noticeable especially when comparing the same record on my other HMV 101. I've checked the governor and it runs smoothly and I've also oiled the governor friction pad generously.

What could be causes for these slight speed undulations? And what could I possible fix/replace to make them go away?

/Rasmus

[Henry]

There could be slippage between the record and the turntable felt, especially if the felt is worn smooth; the tracking weight of the sound box/arm combination will introduce enough friction to "drag" the record, thus affecting rotational speed. Other possibilites include eccentricity (off-center hole in record), and warped record or turntable.

Check your turntable speed with a strobe disc. You may be able to see and confirm slight fluctuations in speed. Of course, that won't tell the cause.

[rasmus.baath]

There could be slippage between the record and the turntable felt, especially if the felt is worn smooth; the tracking weight of the sound box/arm combination will introduce enough friction to "drag" the record, thus affecting rotational speed.

Great tip! Unfortunately this was not the case for me... I marked the turntable and a disc with a piece of silver tape to see how much slippage there was but after playing the record the pieces of tape were still aligned (See picture below).

To get a sense of how the slight speed undulations sound I attach two sound clips of a string tone from the same record. The first is from my good HMV 101, and the second is from the bad one, where you can here that the tone sounds slightly out of tune.

[Henry]

Each clip is only three seconds long, which is not enough for me to evaluate. Can you upload longer clips?

[InkyFeet]

I've just joined the forums as I've recently purchased my first Gramophone, and it's also an HMV model 101. Mine's from 1927/28 I'd guess (winder at the side, nickel plated hardware, manual stop).

I had the problem that on newer (40s/50s) records, the record would slow on louder passages in the music. I found that pulling the needle out as far as I could and still make it hold firmly, the records would play normally due to the slight change in needle angle. Might be worth giving that a try?

(caveat: I'm new to this so if I was making a rookie mistake by inserting my needles as far as they would go before tightening the screw, forgive me...)

I was wondering if my soundbox needed to be rotated a little further (or a little less) but it's on firm and wont budge - I know it should be able to be removed for servicing/swapping soundboxes - is there something I'm doing wrong or is it just on there firm as it's not been removed since manufacture?

Cheers,

Jeff

[CptBob]

Hello everybody, this is my first post, but this seems as good a place as any. I've just bought an HMV 145 on ebay and on some records I get pitch variations very much like the bad clip above. I assumed that an overhaul on to the motor would sort that out, but it seems not.

I'm very new to all of this. Re InkyFeet's post - should you not put the needle all the way in?

[barnettrp21122]

I had a similar problem on my 102 portable. Unfortunately, the problem was a very worn spring barrel shaft bushing, which had worn to an oval shape, causing the barrel gear to alternately press too hard on the spindle as the spring unwound.
You might observe the turntable equipped with a paper strobe disc, and see if the slowdown occurs at the same spot as the barrel rotates.
I ended up replacing parts of the motor from a junked machine.
Bob

[ewok]

My HMV 145 acted the same when I first got it. After I cleaned the spring motor and regreased it, all problems went away!

Hello everybody, this is my first post, but this seems as good a place as any. I've just bought an HMV 145 on ebay and on some records I get pitch variations very much like the bad clip above. I assumed that an overhaul on to the motor would sort that out, but it seems not.

I'm very new to all of this. Re InkyFeet's post - should you not put the needle all the way in?