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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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20th Apr 2020, 5:30 pm | #1 |
Heptode
Join Date: Nov 2018
Location: Staffordshire Moorlands, UK.
Posts: 595
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A Capacitor Query
Can I replace the flat wax type capacitors, with axial type capacitors?
Thank you |
20th Apr 2020, 5:35 pm | #2 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
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Re: A Capacitor Query
No need to replace these Brian. They are silver mica's dipped in wax. They very rarely if ever fail. The other waxies in your picture will of course require replacement. John.
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20th Apr 2020, 5:36 pm | #3 |
Octode
Join Date: Jan 2003
Location: Ware, Herts. UK.
Posts: 1,082
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Re: A Capacitor Query
There is rarely any need to replace this type of capacitor unless they are physically damaged. They use mica or ceramic dielectrics which are reliable over time.
Changing such capacitors in the RF / IF sections of a radio are likely to upset alignment, so you'd be best advised to leave them alone. John |
20th Apr 2020, 5:37 pm | #4 |
Heptode
Join Date: Mar 2016
Location: Essex, UK.
Posts: 602
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Re: A Capacitor Query
The flat L.E.M. capacitors are extremely reliable and do not need replacing. They are pF values and part of the tuned circuits that could upset the tuning if changed.
Just change the round wax covered one of 0.01uf and larger, such as the ones in the left of the picture.
__________________
Geoff |
20th Apr 2020, 5:44 pm | #5 |
Heptode
Join Date: Nov 2018
Location: Staffordshire Moorlands, UK.
Posts: 595
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Re: A Capacitor Query
Phew, thanks all; just saved me a few pounds.
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20th Apr 2020, 8:08 pm | #6 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,949
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Re: A Capacitor Query
Just for the benefit of anyone visiting this thread in future, it is usually only necessary to change capacitors with values between 0.1uF and 0.001uF. Anything smaller than this is likely to be of mica or ceramic construction and not subject to high voltages.
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21st Apr 2020, 9:00 am | #7 |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,507
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Re: A Capacitor Query
For years I swore that S/M capacitors could be ignored as being utterly reliable, until my old 1155 started to go rather deaf on the higher band. Based upon the Sherlock principle of 'when you have eliminated...' I finally discovered the culprit - a S/M padding cap!
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21st Apr 2020, 10:15 am | #8 |
Dekatron
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 9,147
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Re: A Capacitor Query
It's very rare. There is always the odd one but I have never had a faulty tuning /padder cap faulty in 60 years!
I did have a couple of brown lozenge type 100pf silver mica caps fail in The Ekco TS88 9" television line oscillator circuit. They went O/C but I believe that was a stock fault back in it's day. Don't disturb that tuning block and good luck with it! Regards, John. |
21st Apr 2020, 10:31 am | #9 |
Octode
Join Date: Jul 2009
Location: Carmel, Llannerchymedd, Anglesey, UK.
Posts: 1,507
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Re: A Capacitor Query
Disturb it? I had to completely dismantle & re-wire. It was rescued from a skip and the wiring was a congealed mess!
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25th Apr 2020, 7:25 pm | #10 |
Heptode
Join Date: Nov 2018
Location: Staffordshire Moorlands, UK.
Posts: 595
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Re: A Capacitor Query
More very useful information.
Thank you. |