Capacitor question Cossor 494AC. - UK Vintage Radio Repair and Restoration Discussion Forum

gary_crutchley · 5th Jan 2016, 2:00 pm

Hi all,

I have a Cossor 494AC which I want to get up and running. I was looking at changing the AF coupling cap, which on trader sheet 924 is:

C18: 0.1uF.

On the manufacturer's service sheet it is:

C26: 0.01 (no units).

Is there a discrepancy here, or is this just a conversion factor. I'm not sure what units of capacitance Cossor use.

Can someone point me in the correct direction please?

Regards,

Gary

Station X · 5th Jan 2016, 2:42 pm

ERT sheet also says 0.01uF.

What's actually fitted? I'd go for that.

kalee20 · 5th Jan 2016, 2:44 pm

Should be microfarads. Other units could be nanofarads, though these didn't start to be used in industry until the late 1970's, and in any case there is a x1000 difference, not a x10.

The likely value is 0.01µF, though 0.1µF is possible and would work! You will notice hardly any difference. In theory the 0.1µF will give a better bass response; in practice, the benefit would start to kick in at frequencies too low for the speaker and output transformer to cope with anyway.

gary_crutchley · 5th Jan 2016, 3:39 pm

Quote:

Originally Posted by Station X

What's actually fitted? I'd go for that.

I need to check .....

gary_crutchley · 5th Jan 2016, 3:43 pm

Quote:

Originally Posted by kalee20

The likely value is 0.01µF, though 0.1µF is possible and would work! You will notice hardly any difference. In theory the 0.1µF will give a better bass response; in practice, the benefit would start to kick in at frequencies too low for the speaker and output transformer to cope with anyway.

Thanks for your help and advice. The reason I asked is because I have some 0.01uF, but would need to order 0.1uF. I need to get the chassis out and check what is fitted.

Herald1360 · 5th Jan 2016, 6:26 pm

You can try it happily enough with 0.01uF. If it sounds OK, leave it at that even if original was 0.1uF. The set won't care.

gary_crutchley · 5th Jan 2016, 10:56 pm

Quote:

Originally Posted by Station X

What's actually fitted? I'd go for that.

Hi all,

It is fitted with a 0.01uF, and it looks original. I have some replacements in stock for that one luckily.

Thanks for the help and best regards,

Gary

ukcol · 6th Jan 2016, 10:00 am

Quote:

Originally Posted by Station X

ERT sheet also says 0.01uF.

Manufacturer's manual also says it is 0.01uF.

Trader sheet errors are quite common.

5th Jan 2016, 2:00 pm	#1
gary_crutchley Heptode Join Date: Apr 2013 Location: Bloxwich, West Midlands, UK Posts: 554	Capacitor question Cossor 494AC. Hi all, I have a Cossor 494AC which I want to get up and running. I was looking at changing the AF coupling cap, which on trader sheet 924 is: C18: 0.1uF. On the manufacturer's service sheet it is: C26: 0.01 (no units). Is there a discrepancy here, or is this just a conversion factor. I'm not sure what units of capacitance Cossor use. Can someone point me in the correct direction please? Regards, Gary

5th Jan 2016, 2:42 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: Capacitor question Cossor 494AC. ERT sheet also says 0.01uF. What's actually fitted? I'd go for that. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

5th Jan 2016, 2:44 pm	#3
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,088	Re: Capacitor question Cossor 494AC. Should be microfarads. Other units could be nanofarads, though these didn't start to be used in industry until the late 1970's, and in any case there is a x1000 difference, not a x10. The likely value is 0.01µF, though 0.1µF is possible and would work! You will notice hardly any difference. In theory the 0.1µF will give a better bass response; in practice, the benefit would start to kick in at frequencies too low for the speaker and output transformer to cope with anyway.

5th Jan 2016, 6:26 pm	#6
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Capacitor question Cossor 494AC. You can try it happily enough with 0.01uF. If it sounds OK, leave it at that even if original was 0.1uF. The set won't care. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O