28th Feb 2023, 3:01 pm | #1 |
Heptode
Join Date: Jun 2018
Location: Carmarthenshire, Wales, UK.
Posts: 564
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Ekco U428
This radio works OK for 20 minits or so then the sound becomes distorted as if they are taking through water or bubbles I have tested all valves and they all test good. Nothing else has been touched. I don't know where or what might be causing this. Has any one got any ideas what I should be looking for please
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28th Feb 2023, 3:15 pm | #2 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
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Re: Ekco U428
Check the grid coupling capacitor and bias components on the UL84 output valve. The UL84 could also be drawing grid current after 20 mins and could be faulty.
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Frank |
28th Feb 2023, 3:21 pm | #3 |
Hexode
Join Date: Oct 2010
Location: Launceston, Cornwall, UK.
Posts: 292
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Re: Ekco U428
does the radio have any wax coated capacitors? If so, they probably need replacing
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28th Feb 2023, 4:53 pm | #4 |
Heptode
Join Date: Jun 2018
Location: Carmarthenshire, Wales, UK.
Posts: 564
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Re: Ekco U428
Do you know what part no is the grid coupling capacitor on the manufacturer service sheet please. And no there are no wax capacitor or Hunts.
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28th Feb 2023, 5:19 pm | #5 |
Hexode
Join Date: Oct 2010
Location: Launceston, Cornwall, UK.
Posts: 292
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Re: Ekco U428
the Pye 1107 uses the same chassis and I have a Pye 1107 which had the same problem as your Ekco. Try replacing C65 which has a value of 0.01uf.
Paul |
28th Feb 2023, 5:36 pm | #6 |
Hexode
Join Date: Oct 2010
Location: Launceston, Cornwall, UK.
Posts: 292
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Re: Ekco U428
C65 is right next to R36
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28th Feb 2023, 6:13 pm | #7 |
Dekatron
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,595
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Re: Ekco U428
You might find this post helpful: https://www.vintage-radio.net/forum/....php?p=1497567
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28th Feb 2023, 6:30 pm | #8 |
Hexode
Join Date: Oct 2010
Location: Launceston, Cornwall, UK.
Posts: 292
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Re: Ekco U428
C60 (2uf) probably needs replacing and the mains smoothing capacitors are probably past their best too
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