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 Post subject: HMV 102 Portable - earliest version "Universal Brake" video
PostPosted: Sat May 26, 2018 1:36 am 
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Victor IV
Edison, Columbia, Victor, Pathé...and oddball makes
Joined: Sun Jul 08, 2012 1:06 pm
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Here are a couple of videos showing the first version of automatic brake, supplied on the HMV 102 suitcase portable gramophone for only about one year, starting in 1931. It proved to be too complex and/or troublesome and was replaced by a different arrangement on subsequent models.

This one works fine, although it is indeed unusual and complicated.

http://www.youtube.com/watch?v=eRdLt0Zy6Dg

http://www.youtube.com/watch?v=I8fS3X9YX8I

This posting is a branch from an earlier related one, which has a non-descriptive subject line, found here:

viewtopic.php?f=11&t=35043


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Tue May 29, 2018 3:24 am 
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Victor III
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F. Depero, "Grammofono", 1923.
Joined: Thu Feb 24, 2011 4:19 am
Posts: 722
Location: Italy
For those who have time and patience enough to watch it, here is a clip in which the parts, principle and operation of the "mark I" 102 auto-brake is explained in detail, and then put through three severe tests that should confuse it and lean it towards wrong detections/decisions:

- a badly warped record
- a heavily off-centered record
- a record without runout groove and without eccentric end groove

The mark I auto-brake passes all of the three tests without any mistake.

https://youtu.be/W7Y4XF6f5FE


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Tue May 29, 2018 1:52 pm 
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Victor IV
Edison, Columbia, Victor, Pathé...and oddball makes
Joined: Sun Jul 08, 2012 1:06 pm
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Very nice! Mine were very impromptu, and so I’m glad you had the time and inclination to do such a well executed and detailed examination.


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Wed May 30, 2018 3:18 am 
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Victor III
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F. Depero, "Grammofono", 1923.
Joined: Thu Feb 24, 2011 4:19 am
Posts: 722
Location: Italy
Thank you very much Peter! One of the reasons why I did it is that I incidentally spotted that your unit seems not to work correctly (but I don't know if it happened just in the video, as you were perhaps holding some part with your hands etc.). The anchor escapement in your unit seems to get stuck and act tooth-over-tooth, which should never happen. It can be seen at 1:17 and then again at 1:26. If it is so, the auto-brake may probably not stop the turntable as it should when the arm is still (not moved forward).

I believe this is happening because your unit is dirty with sticky dried-up oil; the auto-brake was instead supposed to work dry (only if you have really grasped how every component works and which is its respective funcion, then you can "dare" to apply the most little drop of oil on some of the joins and parts). At first I would try to repeatedly clean it with abundant gasoline, immediately absorbed with a rag. The top arm with the escapement sector (and with the brake tooth at the other side) should be able to move clockwise and counter-clocwise freely; with almost no resistance.

It may also be that the "visible" coil has lost its strength, but before tampering with the coils I warmly suggest that you clean all the mechanism very well first.


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Wed May 30, 2018 8:51 am 
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Victor III
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What a superb video Marco! I have left a comment on YT.

I suppose the one problem it cannot deal with is a runaway at the end of the record, i.e. when the needle escapes the locked groove and skates across the label area - is that correct?


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Wed May 30, 2018 10:29 am 
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Victor III
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F. Depero, "Grammofono", 1923.
Joined: Thu Feb 24, 2011 4:19 am
Posts: 722
Location: Italy
Thank you very much Orchorsol, that's very kind on you!

I agree with the comment you left on YouTube that the bad reputation surrounding the Universal Brake is due to people and repairmen not well understanding its principle, so many of these devices have been accidentally tampered, bending or oiling parts with no clue. The only real mistake that HMV did with this auto-brake in my opinion is not providing an "off" feature for those that could not deal with it. But I think that the videoclip shows fairly well that, when it is well adjusted, you never really need to turn it off.

Coming to your question: it would stop the record also in the case you describe (after 12-18 revolutions of the turntable, as explained in the clip). The needle or the needlebar would probably get hanged on the spindle and the turntable would then be stopped as the arm is stuck there. The turntable is also stopped even if the tonearm is simply put to rest on its resting fork. This said, I think you might agree with me that the simplified "mark II" auto-brake can very hardly be described as an improvement, considered what the mark I was able to do.

You may then wonder how can the motor be fully unwound. It is indeed possible by keeping the tonearm pulled to the right, so that the anchor-escapement device is inhibited as shown in the clip.


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Sun Jun 03, 2018 8:56 pm 
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Victor IV
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Those who were seen dancing were thought insane by those who could not hear the music. Nietzsche
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Marco, your presentation of its function was simple and direct.
The test records have shown its ability to detect an idle position, matching your explanation perfectly.
It is a well designed system.

Thanks for explaining it and for demonstrating its capabilities! :rose:

Peter, your efforts are also appreciated. You too are a geek! :geek:

James.


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Mon Jun 04, 2018 5:24 am 
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Victor III
Joined: Sun Mar 15, 2009 6:18 am
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Very nice video, Marco, and good selection of songs, as well!


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 Post subject: Re: HMV 102 Portable - earliest version "Universal Brake" vi
PostPosted: Mon Jun 04, 2018 5:46 am 
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Victor III
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F. Depero, "Grammofono", 1923.
Joined: Thu Feb 24, 2011 4:19 am
Posts: 722
Location: Italy
Thank you very much James and Carlos!


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