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Other Vintage Household Electrical or Electromechanical Items For discussions about other vintage (over 25 years old) electrical and electromechanical household items. See the sticky thread for details. |
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9th Feb 2018, 12:08 pm | #1 |
Pentode
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
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Repairing electromagnetic bell
I've got an old bell I'm trying to repair. Seems it used to be connected to a 4.5v battery. Dated expiry 1999!
Anyway, the coil seems to be sort of 'sprouting'. There is no continuity between the two rectangled terminals. Is this viable to repair do you think? Thanks |
9th Feb 2018, 12:30 pm | #2 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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Re: Repairing electromagnetic bell
The two rectangled terminals are probably connected to the coils via the bell's interrupter contacts. If the contacts are dirty you won't see continuity. It shouldn't be too difficult to rewind one or both of the coils if necessary. They're wound with thick wire though, so are probably OK.
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9th Feb 2018, 12:33 pm | #3 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,224
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Re: Repairing electromagnetic bell
First of all check for continuity between the right hand terminal in you photo and the pillar above and to the left of the other terminal that carries the fixed contact of the make-and-break. It's possible the problem is just dirty contacts on that pillar and the armature.
The coil could easily be rewound by hand. Many of us made electric bells from scratch when we were younger and wound the coils. It's not very critical. Just count the turns as you unwind it, use the same diamater wire and wind it on as neatly as you can, trying to get the same number of turns on. Oh, and wind the coil the same way as it orginally was. |
9th Feb 2018, 1:23 pm | #4 |
Pentode
Join Date: Mar 2012
Location: Rotherham, South Yorkshire, UK.
Posts: 152
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Re: Repairing electromagnetic bell
Thanks both! And is it possible the two coils are connected by a tiny bit of wire with what looks like a shoe lace knot in the middle? I'll give this a go...
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9th Feb 2018, 4:32 pm | #5 |
Hexode
Join Date: Aug 2017
Location: Taunton, Somerset, UK.
Posts: 318
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Re: Repairing electromagnetic bell
I have a couple of these that I use in the hotel. 4.5V seems low and ought to be checked. Mine used to operate with the old 9V Transistor battery pack but I changed this to a rectified source I knocked up.
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10th Feb 2018, 9:37 pm | #6 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: Repairing electromagnetic bell
4.5V was what the old 126 bell battery with screw terminals produced. Or three wet Leclanche cells.
A bit of serious cleaning and connection scraping will likely have it working (if not looking) as well as new.
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