Capacitor replacement on Sobell 439 - UK Vintage Radio Repair and Restoration Discussion Forum

Northyorks1 · 27th Nov 2019, 11:58 pm

Would it be ok to replace C15 valve 3 cathode bypass, which has a value of 50uf 12v. For a 50uf 25v, or is the voltage critical.

Thanks Ian

Sideband · 28th Nov 2019, 12:16 am

The voltage is only critical if it exceeds the rating of the capacitor. Generally it is OK to go higher on voltage. If the original component is rated at 12 volts then the expected voltage across it in the circuit will be less. Therefore it is perfectly in order to fit a higher voltage component.

It's only a cathode bypass cap so measure the voltage across the resistor with the set working. You'll find it's less than 12 volts so fitting a 25V will be well within the 25V rating.

crackle · 28th Nov 2019, 7:39 am

All that Sideband said, plus you may find it easier to buy a 47uF 25v capacitor or even a 47uf 16v one.

Mike

Northyorks1 · 28th Nov 2019, 1:43 pm

Thanks very much for advice, I do have 47uf 25v so will use that.

Ian

27th Nov 2019, 11:58 pm	#1
Northyorks1 Heptode Join Date: Mar 2018 Location: Saltburn, North Yorkshire, UK. Posts: 623	Capacitor replacement on Sobell 439 Would it be ok to replace C15 valve 3 cathode bypass, which has a value of 50uf 12v. For a 50uf 25v, or is the voltage critical. Thanks Ian

28th Nov 2019, 12:16 am	#2
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,572	Re: Capacitor replacement on Sobell 439 The voltage is only critical if it exceeds the rating of the capacitor. Generally it is OK to go higher on voltage. If the original component is rated at 12 volts then the expected voltage across it in the circuit will be less. Therefore it is perfectly in order to fit a higher voltage component. It's only a cathode bypass cap so measure the voltage across the resistor with the set working. You'll find it's less than 12 volts so fitting a 25V will be well within the 25V rating. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

28th Nov 2019, 7:39 am	#3
crackle Rest in Peace Join Date: Mar 2011 Location: Basildon, Essex, UK. Posts: 4,100	Re: Capacitor replacement on Sobell 439 All that Sideband said, plus you may find it easier to buy a 47uF 25v capacitor or even a 47uf 16v one. Mike

28th Nov 2019, 1:43 pm	#4
Northyorks1 Heptode Join Date: Mar 2018 Location: Saltburn, North Yorkshire, UK. Posts: 623	Re: Capacitor replacement on Sobell 439 Thanks very much for advice, I do have 47uf 25v so will use that. Ian