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Old 23rd Jun 2021, 9:34 am   #1
Dorian27
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Default Ekco U353. Wax Capacitors.

Hi I need to replace 3 wax capacitors they are marked 0.01uf 400vac 1000vdc what modern eq do I need for these please. They are axial capacitors.
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Old 23rd Jun 2021, 9:39 am   #2
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Default Re: Wax Capacitor

Depends where they are and what they're doing......

Are they for RF suppression? Connected across line - neutral or line - earth? Then Class X or Class Y.

Detailed application info needed for relevant recommendations for any other usage.
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Old 23rd Jun 2021, 9:40 am   #3
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Default Re: Wax Capacitor

The type you replace them with would depend on their circuit function.

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Old 23rd Jun 2021, 4:27 pm   #4
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Default Re: Wax Capacitor

They are on an EKCO U353 I have 3 DIFFRENT service sheets for this model and not one matches exactly to this chassis. This has 3 wavebands all 3 capacitor have same value and all are connected to chassis at one end one goes to output transformer one to on/off volume and one to UCH81 VALVE BASE and all go to the chassis
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Old 23rd Jun 2021, 4:56 pm   #5
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Default Re: Wax Capacitor

Can you be more precise?
Which connection on the output transformer?
Is it On/off switch or volume control?
Which pin on the UCH81 valve base?
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Old 23rd Jun 2021, 5:13 pm   #6
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Default Re: Wax Capacitor

I will take some photos it may help
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Old 23rd Jun 2021, 5:32 pm   #7
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Default Re: Wax Capacitor

I said that one goes to valve base well it does not it goes to aerial earth point on earth connections and and chassis. The other goes from on off switch terminal to mains dropper and other from chassis to output transformer yellow speaker cable. I have pics. All are same value 0.01uf 400vac 1000vdc
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Old 23rd Jun 2021, 6:40 pm   #8
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Default Re: Wax Capacitor

dont think thers anything special about those three .so normal 10n[0.01uf] 1000v dc capicitors
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Old 23rd Jun 2021, 6:42 pm   #9
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Default Re: Wax Capacitor

So far as I can make out it looks like replace the one that's connected to the on/off switch with an X Class 2 type and the other two with Y Class 2 types as they look to be safety related.

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Old 23rd Jun 2021, 8:08 pm   #10
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Default Re: Wax Capacitor

Quote:
Originally Posted by gallowfields View Post
dont think thers anything special about those three .so normal 10n[0.01uf] 1000v dc capicitors
Can't seem to find any do you now where I might be able to get these please
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Old 23rd Jun 2021, 8:31 pm   #11
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Default Re: Ekco U353. Wax Capacitors.

I think there IS something special about those capacitors.

That set appears to use a live chassis.... connected to one side of the mains or the other. Two of those capacitors look to be isolators for the aerial and earth sockets. If one or other of these fails, someone could get a full mains electric shock. In current terminology, these need to be "Class Y" safety grade parts, designed not to go short circuit even if they fail. The other one looks to be an interference suppressor across the mains, if so, it should be a "Class X" part. These are designed to survive the sorts of transients found on the mains, and degrade slowly.

Valves with the U prefix mean special ones designed for live chassis operation (no mains transformer so no low voltage supply for heaters) They get connected across the mains in a long string to suit the high voltage, with a series resistor to allow for mains voltage adjustment.

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Old 23rd Jun 2021, 9:05 pm   #12
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Default Re: Ekco U353. Wax Capacitors.

Manufacturer's service sheet shows:-

C1 wired chassis to signal earth socket. Replace with Class Y. (Trader Sheet C2).
C61 wired across the mains supply. Replace with Class X. (Trader Sheet C60).

I can't see a third capacitor which needs to be class X or Y, but no doubt someone will correct me.
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Old 23rd Jun 2021, 9:14 pm   #13
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Default Re: Ekco U353. Wax Capacitors.

Quote:
Originally Posted by Station X View Post
I can't see a third capacitor which needs to be class X or Y, but no doubt someone will correct me.
C3 manufactures and Trader, Y2 Class.

(Post#9)

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Old 23rd Jun 2021, 9:19 pm   #14
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Default Re: Ekco U353. Wax Capacitors.

I think I will leave the wax ones in place. Not experienced enough to now which one's to get. The radio does work just someone said it is best to replace wax capacitors
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Old 23rd Jun 2021, 9:25 pm   #15
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Default Re: Ekco U353. Wax Capacitors.

Quote:
Originally Posted by Radio Wrangler View Post
Valves with the U prefix mean special ones designed for live chassis operation (no mains transformer so no low voltage supply for heaters)
Some receivers do have transformers for series heaters, record players too in the form of a motor tap.

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Old 23rd Jun 2021, 9:29 pm   #16
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Default Re: Ekco U353. Wax Capacitors.

Quote:
Originally Posted by Dorian27 View Post
I think I will leave the wax ones in place. Not experienced enough to now which one's to get. The radio does work just someone said it is best to replace wax capacitors
Replace with the types that myself and others have recommended before you get an electric shock This is a Live chassis design receiver with external connections (Earth also FM antenna and Extension Loudspeaker if it's the early type) that are connected to chassis via two of those capacitors, that's to say that under certain circumstances without an isolating transformer the chassis could rise to a voltage with resect to Earth that equals the mains voltage of say 240 volts AC....Approx 340 volts peak AC...With plenty of current to go with it and through those old wax capacitors should they fail.

The capacitors are readily available.

Lawrence.

Last edited by ms660; 23rd Jun 2021 at 9:53 pm. Reason: extra info
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Old 24th Jun 2021, 12:56 pm   #17
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Default Re: Wax Capacitor

Quote:
Originally Posted by Dorian27 View Post
I said that one goes to valve base well it does not it goes to aerial earth point on earth connections and and chassis. The other goes from on off switch terminal to mains dropper and other from chassis to output transformer yellow speaker cable. I have pics. All are same value 0.01uf 400vac 1000vdc
Could you post a snippet of the circuit diagram showing where these capacitors are in the circuit? It's much easier to provide an informed reply rather than guessing. These old capacitors will not be providing adequate isolation (if that is what they are for) so should be replaced.

From your description I would think that one is a tone corrector (the one that goes to the yellow wire) so that can be a normal polyester type 0.01uF 1000V, the one to aerial and earth point is for isolation so that should be a 'Y' type and the one to the dropper is probably a mains filter so should be and 'X' type if across the mains or a 'Y' type if going to chassis.

Positive identification from the circuit will conform this (or prove otherwise)!
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Last edited by Sideband; 24th Jun 2021 at 1:03 pm.
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Old 24th Jun 2021, 5:43 pm   #18
Dorian27
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Default Re: Ekco U353. Wax Capacitors.

I cans seem to find these for sale anywhere. And not sure what to look for. Or where or what to ask for. Completely lost on this one.
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Old 24th Jun 2021, 5:56 pm   #19
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Default Re: Ekco U353. Wax Capacitors.

Has Sideband asked, post circuit snippets.
X rated capacitors suitable for across the mains input are available from Cricklewood, but we need to be sure exactly where they are in the circuit.
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Old 24th Jun 2021, 8:37 pm   #20
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Default Re: Ekco U353. Wax Capacitors.

These are the circuit diagrams with 2 of the capacitors the capacitor going from chassis to output transformer is not shown on circuit diagram. But as I said it is the same value and power voltage as the other ones. 0.01uf 400vac 1000dc. That's all I can tell you.First is C2 and C60 mains switch tag with green wire going to dropper
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