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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 1st Nov 2007, 11:22 pm   #1
PJL
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Default 1920's headphones rewind

Something completely different...but I thought it might encourage others to have a go.

A previous repairer had pulled the wires from one o/c coil to make a connection to complete the circuit whilst another coil showed as open. The cable was broken and bindings had come loose.

I thought these worth restoring as they unusually have an adjustment wheel for the diaphragm gap which would have been used to compensate for DC current in early valve sets. They are marked C.A.C. 4000 OHMS LONDON and PROV. PAT 220066 and would estimate they date from around 1924?

I made a jig for hand winding small coils to repair a horn speaker https://www.vintage-radio.net/forum/...ad.php?t=21516. I rewound the wrecked coil with 4600 turns of 46SWG calculating the number of turns using the resistance of the wire, resistance of a good winding and estimating the length of a turn. The other coil was typical of other headphones I have repaired and had a failed connection to the lead out wire from damp in the paper that is used to finish the winding off. I used PTFE tape instead of paper.

Small gauge wire is alot stonger than you might imagine and I have now completed my third 4500+ turn rewind and have not broken it once...
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Old 2nd Nov 2007, 12:50 am   #2
Station X
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Default Re: 1920's headphones rewind

Well done. It's amazing what it's possible to do if you only have the courage to try.

I'm ashamed to say that I have a "proper" coilwinder, but have never used it.
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Old 2nd Nov 2007, 11:30 am   #3
PJL
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Default Re: 1920's headphones rewind

Rewinding is very therapeutic. I had 4 headphones with o/c coils but most turned out to be the lead out wire connection. All I have left is a Ferranti AF5 but my jig will need reworking to hold a spool that size.

These early coils/transformers are easy to do as they are rough wound...Peter
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