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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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29th Nov 2020, 12:16 pm | #1 |
Heptode
Join Date: Apr 2016
Location: Croxley Green, Hertfordshire, UK.
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Loud pop when turntable switches off
I've recently restored and Bush SRP31D and very pleased with it's performance but its just developed an annoying fault.
After it's finished playing a record and the arm returns to the cradle the turntable automatically switches off and makes quite a loud popping noise from the speaker. I'm wondering what's causing this and how to sort it out! Thanks
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Clive |
29th Nov 2020, 12:19 pm | #2 |
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Re: Loud pop when turntable switches off
The cause is likely to be due to the switch contacts arcing. I suggest you add a capacitor of about 10nF across the contacts, or perhaps a suppressor which is usually a C & R in series.
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29th Nov 2020, 12:21 pm | #3 |
Dekatron
Join Date: Sep 2015
Location: Southwold, Suffolk, UK.
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Re: Loud pop when turntable switches off
It needs a "switch click suppressor" - in other words a large value (c 0.1uF 500V) cap wired across the motor switch. They used to be standard on some higher end Garrard turntables.
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Edward. |
29th Nov 2020, 7:12 pm | #4 |
Heptode
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Re: Loud pop when turntable switches off
Thanks very much for the advice, will add the said capacitor tomorrow and report back.
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Clive |
29th Nov 2020, 10:09 pm | #5 |
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Re: Loud pop when turntable switches off
I think 0.1uF is too big unless it includes a series resistor, thats why I suggested 10nF (0.01uF), make sure its an X rated type, ie 275V AC.
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30th Nov 2020, 1:20 am | #6 |
Octode
Join Date: Jul 2011
Location: Staffordshire Moorlands, UK.
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Re: Loud pop when turntable switches off
Absolutely agree.
Steve.
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30th Nov 2020, 9:20 am | #7 |
Nonode
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Location: Aberaeron, Ceredigion, Wales, UK.
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Re: Loud pop when turntable switches off
Just as an observation I note that 0.1ufd are used in some Bush Radios, without a series resistor.
John |
30th Nov 2020, 9:53 am | #8 |
Dekatron
Join Date: Oct 2003
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Re: Loud pop when turntable switches off
I have found purpose made snubbers very helpful for this.
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Paul |
30th Nov 2020, 10:02 am | #9 |
Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
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Re: Loud pop when turntable switches off
Reference my post #7, I was thinking of mains suppression so please ignore my observations, must put brain into gear
John |
30th Nov 2020, 1:05 pm | #10 | |
Heptode
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Re: Loud pop when turntable switches off
Quote:
I've checked my "stock" and found I have just 1 uF and .22 uF X rated (275V) capacitors, I don't know how critical this is, will either of those do or should I order a 0.01 uF as recommended?
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Clive |
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30th Nov 2020, 3:06 pm | #11 |
Dekatron
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Re: Loud pop when turntable switches off
Much too high. Best order a .01 (10nF) 275V.
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30th Nov 2020, 6:36 pm | #12 |
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Re: Loud pop when turntable switches off
A 0.22uF with 100 ohms in series will be fine.
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30th Nov 2020, 9:08 pm | #13 |
Dekatron
Join Date: Oct 2003
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Re: Loud pop when turntable switches off
Best thing to do is just try it. Sometimes theory and practice don't always go hand in hand!!
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4th Dec 2020, 1:02 pm | #14 |
Heptode
Join Date: Apr 2016
Location: Croxley Green, Hertfordshire, UK.
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Re: Loud pop when turntable switches off
The first couple of posts suggested the cap is wired across the motor switch contacts. I assume this is in parallel.
Anyway, I've received the correct rated capacitor and wired it in as this and it's sorted out the problem, hardly any noise to worry about now, many thanks for the help
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Clive |
4th Dec 2020, 1:29 pm | #15 |
Hexode
Join Date: Dec 2018
Location: Sheffield, South Yorkshire, UK.
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Re: Loud pop when turntable switches off
so what type and value cap did you use.
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4th Dec 2020, 3:06 pm | #16 |
Heptode
Join Date: Apr 2016
Location: Croxley Green, Hertfordshire, UK.
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Re: Loud pop when turntable switches off
0.01uF, X rated type, 300V
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Clive |
4th Dec 2020, 5:06 pm | #17 |
Heptode
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Re: Loud pop when turntable switches off
Question to the boffins - if you have a double pole switch where live cannot be determined (European plugs) then two capacitors should be fitted? Or is it just one for the whole circuit?
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4th Dec 2020, 6:30 pm | #18 |
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Re: Loud pop when turntable switches off
One across each switch, the "liveness" doesn't matter, one will switch first. Which one one never knows. (The first time I have done "one one")
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