Caps for Mullard E7600/3 - UK Vintage Radio Repair and Restoration Discussion Forum

humphrey · 2nd Dec 2008, 6:57 pm

I am changing all the old caps but have a query. The four 16mf x 350v seem easy enough but there are two large 4mf 475v. What is recommended?
I usually get my stuff from just radios in Canada.

Vicboduk · 2nd Dec 2008, 8:08 pm

4.7uF 450v are readily available – I would measure the voltage across the existing capacitor, and if it’s less than 450v no problem. Remember to allow for a drop in voltage value if it’s for supply smoothing and the capacitance has decreased. Or calculate the voltage needed based on the transformer secondary voltage. It could just be that at the time your tester was made the next value up from 350v was 475v.
Others with more experience than me could probably confirm this.

Vic

humphrey · 3rd Dec 2008, 12:22 pm

The voltage is 475v, or at least should be according to some testing sheets that I have just come across. I guess that rules out 4uf 450v?
Any sources?

Station X · 3rd Dec 2008, 1:36 pm

If there's room you could use two 8uF OR 10uF capacitors in SERIES with a 470K equalising resistor across each.

humphrey · 3rd Dec 2008, 7:08 pm

I will get some 8uf x 250v. Will that give 4uf x 500v?

Station X · 3rd Dec 2008, 7:10 pm

Yes, so long as they're in series.

humphrey · 3rd Dec 2008, 9:50 pm

The two 4uf x 475v caps have 2.2meg resistors across them.

Station X · 3rd Dec 2008, 9:57 pm

They're probably bleeder resistors designed to discharge the capacitors when the power is removed. If you leave them out the 470K equalising resistors will do the job just as well.

Colin · 3rd Dec 2008, 11:46 pm

I replaced the 4.7uf 450V electrolytics on my E7600 with two pairs of 10uF 400V caps. As there was plenty of headroom on the combined voltage rating I didn't use any equalising resistors, but I did replace the 2M2 bleeder resistors. Works fine!

Colin

humphrey · 4th Dec 2008, 10:11 am

Thanks for the help. Now for the resistors.

2nd Dec 2008, 6:57 pm	#1
humphrey Retired Dormant Member Join Date: Aug 2008 Location: Bellac, 87. France. Posts: 357	Caps for Mullard E7600/3 I am changing all the old caps but have a query. The four 16mf x 350v seem easy enough but there are two large 4mf 475v. What is recommended? I usually get my stuff from just radios in Canada. Last edited by humphrey; 2nd Dec 2008 at 7:01 pm. Reason: none

2nd Dec 2008, 8:08 pm	#2
Vicboduk Hexode Join Date: Aug 2007 Location: S.W. London, UK. Posts: 416	Re: Caps for Mullard E7600/3 4.7uF 450v are readily available – I would measure the voltage across the existing capacitor, and if it’s less than 450v no problem. Remember to allow for a drop in voltage value if it’s for supply smoothing and the capacitance has decreased. Or calculate the voltage needed based on the transformer secondary voltage. It could just be that at the time your tester was made the next value up from 350v was 475v. Others with more experience than me could probably confirm this. Vic __________________ It has to be here... I've just put it down!

3rd Dec 2008, 12:22 pm	#3
humphrey Retired Dormant Member Join Date: Aug 2008 Location: Bellac, 87. France. Posts: 357	Re: Caps for Mullard E7600/3 The voltage is 475v, or at least should be according to some testing sheets that I have just come across. I guess that rules out 4uf 450v? Any sources?

3rd Dec 2008, 1:36 pm	#4
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: Caps for Mullard E7600/3 If there's room you could use two 8uF OR 10uF capacitors in SERIES with a 470K equalising resistor across each. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

3rd Dec 2008, 7:08 pm	#5
humphrey Retired Dormant Member Join Date: Aug 2008 Location: Bellac, 87. France. Posts: 357	Re: Caps for Mullard E7600/3 I will get some 8uf x 250v. Will that give 4uf x 500v?

3rd Dec 2008, 7:10 pm	#6
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: Caps for Mullard E7600/3 Yes, so long as they're in series. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

3rd Dec 2008, 9:50 pm	#7
humphrey Retired Dormant Member Join Date: Aug 2008 Location: Bellac, 87. France. Posts: 357	Re: Caps for Mullard E7600/3 The two 4uf x 475v caps have 2.2meg resistors across them.

3rd Dec 2008, 9:57 pm	#8
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,287	Re: Caps for Mullard E7600/3 They're probably bleeder resistors designed to discharge the capacitors when the power is removed. If you leave them out the 470K equalising resistors will do the job just as well. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

3rd Dec 2008, 11:46 pm	#9
Colin Heptode Join Date: Jun 2004 Location: Ilkley, West Yorkshire, UK. Posts: 656	Re: Caps for Mullard E7600/3 I replaced the 4.7uf 450V electrolytics on my E7600 with two pairs of 10uF 400V caps. As there was plenty of headroom on the combined voltage rating I didn't use any equalising resistors, but I did replace the 2M2 bleeder resistors. Works fine! Colin Attached Thumbnails __________________ Colin Armstrong

4th Dec 2008, 10:11 am	#10
humphrey Retired Dormant Member Join Date: Aug 2008 Location: Bellac, 87. France. Posts: 357	Re: Caps for Mullard E7600/3 Thanks for the help. Now for the resistors.