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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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24th Jun 2021, 9:38 pm | #21 |
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Re: Ekco U353. Wax Capacitors.
C3 isn't 0.01uf 400vac 1000vdc, as specified by the OP though, but I take your point that it needs to be Class Y.
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24th Jun 2021, 10:00 pm | #22 | |
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Re: Wax Capacitor
Quote:
https://www.cricklewoodelectronics.c...Capacitor.html Picture 2 shows C1 which needs to be a 0.01uF Class Y type. There is no need for this to be rated at 1000V. I think they're normally rated at 275VAC. Picture 4 shows C61 which needs to be a 0.01uF Class X type. Once again I think these are rated at 275VAC. https://www.cricklewoodelectronics.com/CXR10N.html Designations refer to the manufacturer's service sheet.
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25th Jun 2021, 10:28 am | #23 | ||
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Re: Ekco U353. Wax Capacitors.
Quote:
Quote:
Lawrence. |
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25th Jun 2021, 10:45 am | #24 |
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Re: Ekco U353. Wax Capacitors.
I've just realised that I have the Ferranti version of this set, the U1032. I changed the waxies years ago without giving it a second thought. I'll take a look inside later and see how the tone correction capacitor is wired.
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25th Jun 2021, 11:05 am | #25 |
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Re: Ekco U353. Wax Capacitors.
There's no tone correction capacitor connected to the output transformer in the schematics I have.
There isn't one in this Ferranti U1032 either that I can see: https://www.vintage-radio.net/forum/...1&d=1282575693 Lawrence. |
25th Jun 2021, 11:52 am | #26 |
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Re: Ekco U353. Wax Capacitors.
So what is that capacitor then. You say it's wired across C3, so it can't be that. Is there an undocumented capacitor? If so what is its function?
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25th Jun 2021, 12:16 pm | #27 |
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Re: Ekco U353. Wax Capacitors.
All I know is that if it's going to be replaced it should be replaced with a Y Class type if the extension loudspeaker sockets are still connected to the loudspeaker, C3 as originally fitted to the earlier chassis was mounted topside of the chassis according to the layout info.
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25th Jun 2021, 12:28 pm | #28 |
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Re: Ekco U353. Wax Capacitors.
So what capacitor do I use on the transformer. Or can I leave it without one or leave the old wax capacitor as it is
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25th Jun 2021, 12:38 pm | #29 |
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Re: Ekco U353. Wax Capacitors.
Take your pick:
https://uk.farnell.com/w/c/passive-c...ating-y=300vac Other suppliers are available. Lawrence. |
25th Jun 2021, 2:11 pm | #30 |
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Re: Ekco U353. Wax Capacitors.
One side of the loudspeaker in the Ekco U319 is also connected to chassis via a 0.01uF capacitor, so far as its function goes for the loudspeaker circuit I can only think that it's there for RF de-coupling purposes to prevent any RF picked up by an extension loudspeaker cable from being introduced into the -ve feedback winding and finding its way back to the input of the AF amplifier.
Lawrence. |
25th Jun 2021, 4:43 pm | #31 |
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Re: Ekco U353. Wax Capacitors.
Hi Dorian27, I think it is safest to replace it with the recommended part, which is designed to fulfill a safety role as well as a circuit role.
Those wax capacitors will bite you one day, so it is a worthwhile exercise that you are persevering with these changes! |
25th Jun 2021, 5:15 pm | #32 |
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Re: Ekco U353. Wax Capacitors.
I took the back off my Ferranti U1032 which is similar to the Ekco U353.
All component references in what follows are from the manufacturer's service sheet for the Ekco U353. Going right back to post #1 the OP queried three 0.1uF 1000VDC wax capacitors. These are:- C1 wired from the signal earth socket to chassis. I had replaced this with a 0.01uF Class Y capacitor as shown in the picture. C61 wired across the mains supply on the output side of the mains switch, or wired between one side of the mains supply on the output side of the mains switch and chassis, which amounts to the same thing electrically. I had replaced this with a 0.01uF Class X capacitor as shown in the picture. An undocumented capacitor wired from the output transformer to ground. My set was not fitted with this capacitor. Perhaps it was only fitted to some sets? I've posted a picture showing the absence of this capacitor. C3 has also been mentioned in this thread, but I don't think the OP queried it. It's 1800pF and mounted on the side of the VHF Tuner Unit at the end of the balanced pair of wires from the VHF aerial socket. I have not replaced this capacitor and it would not occur to me to replace a capacitor of this type and value. I've posted a picture of it for completeness. It would be interesting to know whether C3 is fitted to the OP's set.
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25th Jun 2021, 5:39 pm | #33 |
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Re: Ekco U353. Wax Capacitors.
On my Ferranti U1032, manufacturers circuit.
C1, signal earth to chassis, I removed this as the earth socket connection would never be used but would have used a Y class if I had done. C61 replaced with class X. C3 was replaced with a class Y due to the possibility of its failure causing a danger if using an external aerial. My set did not have the undocumented capacitor on the output transformer.
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23rd Aug 2021, 5:51 pm | #34 |
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Ekco U353
Can any one help i am a novice and i have the above set and i need to replace R36 resistor it is marked welwyn does it have to be a welwyn or will another replacement do. Could you recomend an alternative if there is. And what wattage should the replacement be please
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23rd Aug 2021, 6:12 pm | #35 |
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Re: Ekco U353. Wax Capacitors and resistor replacement.
Obviously referring to the Trader sheet, as there is no R36 shown on the manufacturer's sheet?
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23rd Aug 2021, 6:32 pm | #36 |
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Re: Ekco U353. Wax Capacitors and resistor replacement.
So far as I can make out some of the voltage and current figures in the service info don't tally up (The Manufactures and thus Trader)
That said the load current is quoted as 85mA with FM selected with a mains voltage of 240 Volts. From that you can easily figure out how much power the resistor will want to dissipate using our old friend P=Isquared*R, that returns a power dissipation figure of approx. 2.38 Watts, for a happy life that figure should be doubled and the result used as a guide to the minimum power rating required, the nearest to that would be a 5 Watt resistor of the correct value. Lawrence. Last edited by ms660; 23rd Aug 2021 at 6:39 pm. Reason: extra info |
23rd Aug 2021, 6:35 pm | #37 |
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Re: Ekco U353. Wax Capacitors and resistor replacement.
I have the trader sheet in front of me and it is there it is connected to the can capacitor and output transformer 330ohm welwyn Trader sheet 1448
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23rd Aug 2021, 6:46 pm | #38 |
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Re: Ekco U353. Wax Capacitors and resistor replacement.
If the original R36 is a wirewound one and its resistance is correct (330R +/- 20%) then it'll be fine even if it looks quite manky. Otherwise, a Welwyn W22 330R would be the ideal replacement but any 5-6W wirewound type will do.
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23rd Aug 2021, 7:20 pm | #39 |
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Re: Ekco U353. Wax Capacitors and resistor replacement.
Better described as the smoothing resistor. in a CRC smoothing circuit.
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23rd Aug 2021, 7:30 pm | #40 |
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Re: Ekco U353. Wax Capacitors and resistor replacement.
Thank you for helping me
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