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 Healing 408A radio
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 Return to top of page · Post #: 1 · Written at 3:29:59 PM on 23 August 2020.
Tonyb's Gravatar
 Location: Lawnton, QLD
 Member since 6 March 2018
 Member #: 2223
 Postcount: 5

Hi
I'm trying to get a Healing 408a 6v radio going, and a stand up dual capacitor tin can has rusted.
The schematics say its 500mf on both sides
It is connected to both sides of the heating filament of the 1D4 valve
What does it actually do?
Also is 500mf right? voltage unknown but assume low voltage.
Vermin had made home in it years ago, but bakelite cabinet is complete and in mint condition.


 
 Return to top of page · Post #: 2 · Written at 3:53:50 PM on 23 August 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1910

Yes they would have been 500μF 6 volts. They are there to keep the vibrator hash out of the filament line.

A couple of 470μF 6v electros should be fine. I looked up 470μF in a ceramic cap, you can get them but they are over $10 each!


 
 Return to top of page · Post #: 3 · Written at 7:52:36 PM on 23 August 2020.
Tonyb's Gravatar
 Location: Lawnton, QLD
 Member since 6 March 2018
 Member #: 2223
 Postcount: 5

Thanks
I've cleaned and rust converted the nickel plated chassis and freed/cleaned the tuner up
The end cap came adrift off the twin capacitor. They're only tin plated.
Was going to clean and paint these flat black
Next project will be tackling underneath.
I haven't tested them yet or will they be dead?
thanks Tony


 
 Return to top of page · Post #: 4 · Written at 8:05:11 PM on 23 August 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6013

I haven't tested them yet or will they be dead?

If you're talking about capacitors, then assuming they are all old/original the usual approach (if you don't want to revisit the set) is to replace all of the electrolytics and any wax/paper capacitors.

Check resistor values as you go.


 
 Return to top of page · Post #: 5 · Written at 8:47:10 PM on 23 August 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1910

Yeah, not worth trying to re-form those two caps! To work as intended removing the vibrator hash they need a very low ESR so new ones are highly recommended.

Are you OK to restore the vibrator? I notice that Kevin Chant has a solid state vibrator replacement.

https://www.kevinchant.com/

The mechanical noise of a vibrator in a table radio gets very annoying after a while and was one of the reasons why as a bush radio they weren't as popular as they should have been.


 
 Return to top of page · Post #: 6 · Written at 3:57:26 PM on 24 August 2020.
BurntOutElectronics's Gravatar
 Location: Melbourne, VIC
 Member since 2 October 2019
 Member #: 2392
 Postcount: 154

Interesting I never knew about Kevin's vibrator eliminator. Ive heard of ones using 2n3055's though and very simple but Ive never had to build one. I do have a few NOS vibrators around here too.


 
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