Electrolytics in '30s Set? - UK Vintage Radio Repair and Restoration Discussion Forum

fidobsa · 29th Dec 2010, 11:44 am

I'm in the process of re-stuffing the capacitor block in my HMV 540 radiogram. I ordered the new capacitors a few months ago. At the time I noticed there were no electrolytics shown in the trader sheet circuit diagram but did not give it much thought. The block contains several 1 Mfd capacitors and I bought non electrolytics for those but I bought 2.2Mfd and 4.7Mfd electrolytics to replace the old 2Mfd and 5Mfd ones. I'm now wondering if this is considered bad practice, as I'm introducing a later technology than was available at the time of manufacture? (electrolytics were available but their reliability was poor) Now I have the block apart I can see that the 5Mfd capacitor is made up of two 2Mfd and one 1Mfd capacitors in parallel. Do you think I should order some more of the 1Mfd non electrolytics and make up the larger values that way?

evingar · 29th Dec 2010, 11:49 am

This is very subjective. The non electrolytic capacitors you are considering would most likely also use technology not available at the time of the sets manufacture. From a practical point of view, the advantage of the non electrolytic route would most likely be a greater life span - but they will probably cost more.

Sideband · 29th Dec 2010, 8:44 pm

Conversely, I used some non-electrolytic types to replace some electrolytics. These were 1uf's that I paralleled to replace 2uF and 4uF electrolytic types. I had a large number of these values at the time and was working on a very tight budget.

It's up to you. Either will be OK. Unless there is any reason for the ripple current to be high (probably not) then the electro's will be fine.

SB

AC/HL · 30th Dec 2010, 1:53 am

Electrolytic technology was only used because conventional could not squeeze sufficient capacity into small spaces at the time, as I understand it. Capacity is capacity and if you can get it using non-electrolytic techniques so much the better. Once the can is sealed who knows what magic is in there. You can get a 1.8uF 250v capacitor from an old telephone master socket which will replace any old 1 or 2 uF capacitor (sorry, condenser).
Reservoir and smoother capacitors are specialised, but the others are fair game.

29th Dec 2010, 11:44 am	#1
fidobsa Retired Dormant Member Join Date: Mar 2009 Location: Zala, Hungary Posts: 418	Electrolytics in '30s Set? I'm in the process of re-stuffing the capacitor block in my HMV 540 radiogram. I ordered the new capacitors a few months ago. At the time I noticed there were no electrolytics shown in the trader sheet circuit diagram but did not give it much thought. The block contains several 1 Mfd capacitors and I bought non electrolytics for those but I bought 2.2Mfd and 4.7Mfd electrolytics to replace the old 2Mfd and 5Mfd ones. I'm now wondering if this is considered bad practice, as I'm introducing a later technology than was available at the time of manufacture? (electrolytics were available but their reliability was poor) Now I have the block apart I can see that the 5Mfd capacitor is made up of two 2Mfd and one 1Mfd capacitors in parallel. Do you think I should order some more of the 1Mfd non electrolytics and make up the larger values that way?

29th Dec 2010, 11:49 am	#2
evingar Octode Join Date: Oct 2003 Location: Newbury, Berkshire, UK. Posts: 1,770	Re: Electrolytics in '30s Set? This is very subjective. The non electrolytic capacitors you are considering would most likely also use technology not available at the time of the sets manufacture. From a practical point of view, the advantage of the non electrolytic route would most likely be a greater life span - but they will probably cost more. __________________ Chris

29th Dec 2010, 8:44 pm	#3
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,580	Re: Electrolytics in '30s Set? Conversely, I used some non-electrolytic types to replace some electrolytics. These were 1uf's that I paralleled to replace 2uF and 4uF electrolytic types. I had a large number of these values at the time and was working on a very tight budget. It's up to you. Either will be OK. Unless there is any reason for the ripple current to be high (probably not) then the electro's will be fine. SB __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

30th Dec 2010, 1:53 am	#4
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,643	Re: Electrolytics in '30s Set? Electrolytic technology was only used because conventional could not squeeze sufficient capacity into small spaces at the time, as I understand it. Capacity is capacity and if you can get it using non-electrolytic techniques so much the better. Once the can is sealed who knows what magic is in there. You can get a 1.8uF 250v capacitor from an old telephone master socket which will replace any old 1 or 2 uF capacitor (sorry, condenser). Reservoir and smoother capacitors are specialised, but the others are fair game.