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HMV No. 21 Soundbox

Posted: Wed May 20, 2015 8:54 am
by Gram1948
My HMV 21 Soundbox, along with some others in my collection has two small machine screws positioned either side the pivot for the needlebar and seled in position with wax. It would appear their purpose is to somehow limit the movement of the needle bar but does anyone know exactlywhat there purpose is and how they are set?

Re: HMV No. 21 Soundbox

Posted: Wed May 20, 2015 12:13 pm
by Phototone
Your supposition is exactly right. They serve to limit the travel of the needle bar to prevent it from tearing the diaphragm if it were dropped or mishandled. In normal use, they DO NOT touch the needle bar.

Re: HMV No. 21 Soundbox

Posted: Wed May 20, 2015 4:09 pm
by Gram1948
Thanks Phototone...yes obvious when you think about it. I just thought maybe I was missing a trick somewhere.

Many thanks