A Capacitor Query - UK Vintage Radio Repair and Restoration Discussion Forum

BrianAllen · 20th Apr 2020, 5:30 pm

Can I replace the flat wax type capacitors, with axial type capacitors?

Thank you

Heatercathodeshort · 20th Apr 2020, 5:35 pm

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.

jjl · 20th Apr 2020, 5:36 pm

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

GeoffK · 20th Apr 2020, 5:37 pm

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.

BrianAllen · 20th Apr 2020, 5:44 pm

Phew, thanks all; just saved me a few pounds.

paulsherwin · 20th Apr 2020, 8:08 pm

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.

lesmw0sec · 21st Apr 2020, 9:00 am

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!

Heatercathodeshort · 21st Apr 2020, 10:15 am

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.

lesmw0sec · 21st Apr 2020, 10:31 am

Disturb it? I had to completely dismantle & re-wire. It was rescued from a skip and the wiring was a congealed mess!

BrianAllen · 25th Apr 2020, 7:25 pm

More very useful information.

Thank you.

20th Apr 2020, 5:30 pm	#1
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	A Capacitor Query Can I replace the flat wax type capacitors, with axial type capacitors? Thank you Attached Thumbnails

20th Apr 2020, 5:35 pm	#2
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	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.

20th Apr 2020, 5:36 pm	#3
jjl Octode Join Date: Jan 2003 Location: Ware, Herts. UK. Posts: 1,082	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
GeoffK Heptode Join Date: Mar 2016 Location: Essex, UK. Posts: 602	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
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Re: A Capacitor Query Phew, thanks all; just saved me a few pounds.

20th Apr 2020, 8:08 pm	#6
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	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.

21st Apr 2020, 9:00 am	#7
lesmw0sec Octode Join Date: Jul 2009 Location: Carmel, Llannerchymedd, Anglesey, UK. Posts: 1,507	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!

21st Apr 2020, 10:15 am	#8
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	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
lesmw0sec Octode Join Date: Jul 2009 Location: Carmel, Llannerchymedd, Anglesey, UK. Posts: 1,507	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!

25th Apr 2020, 7:25 pm	#10
BrianAllen Heptode Join Date: Nov 2018 Location: Staffordshire Moorlands, UK. Posts: 595	Re: A Capacitor Query More very useful information. Thank you.