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 Post subject: odd metal capacitor in Webster-Chicago Wire recorder
PostPosted: Apr Sun 14, 2019 2:44 am 
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Joined: Mar Tue 26, 2019 12:41 am
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I am restoring a webster-chicago wire recorder from 1956. It's in very good shape, powered up, but shorted a 1 Amp heathkit-type plug fuse when placed into run mode. I have new rectifier and 3 additional tubes for it. Basically I am replacing capacitors and resistors. These are typical paper/wax capacitors.
I have run into the pictured 0.01 MFD metal capacitor with its case grounded. It is in the microphone portion of the schematic. I am assuming this was an early attempt to shield this part of the circuit, prevent hum and/or distortion. The cap output wire is shielded in a coaxial grounding sheath as well which I was planning to retain.
Is there any reason I could not replace this with a typical polypropylene cap, (and dispense with the case grounding obviously)? Or would it be wiser to leave the capacitor unreplaced, assuming it tested ok?


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 Post subject: Re: odd metal capacitor in Webster-Chicago Wire recorder
PostPosted: Apr Sun 14, 2019 2:57 am 
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Joined: Feb Wed 07, 2018 6:52 pm
Posts: 460
Location: Stone Mountain, GA
If it tests ok, leave it in. I've not seen one fail.

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 Post subject: Re: odd metal capacitor in Webster-Chicago Wire recorder
PostPosted: Apr Mon 15, 2019 3:45 pm 
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Joined: Jun Sun 23, 2013 9:03 pm
Posts: 432
Location: Canandaigua, NY
If one did replace it, just add a wrap of copper foil tape and ground it. I found those units to be quite difficult to service because of access to some parts, but very rewarding. Sound quality was way better than I would have thought. Lubrication and type of lube on moving parts is important.


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 Post subject: Re: odd metal capacitor in Webster-Chicago Wire recorder
PostPosted: Apr Tue 23, 2019 2:12 am 
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Joined: Mar Tue 26, 2019 12:41 am
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Thanks for the reply

What type of lubrication did you use? There is only one worm gear in there, a drive for the spool. I have used a watchmakers grease for these types of applications, it has seemed to hold up well. What do you recommend?


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 Post subject: Re: odd metal capacitor in Webster-Chicago Wire recorder
PostPosted: Apr Tue 30, 2019 4:46 pm 
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Joined: Jun Sun 23, 2013 9:03 pm
Posts: 432
Location: Canandaigua, NY
The metal piece that carries the head slides up and down. I think I used a moly grease on the contact areas of that. I remember also having to go in with a long tube to lube one of the motor bearings. I use lightweight hydraulic oil for those.


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