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Switch popping

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Anonymous
January 28, 2005 11:26:31 AM

Archived from groups: rec.audio.pro (More info?)

A correspondent asks the following question: He has a turntable with a
115VAC synchronous motor; he's using a standard light switch to turn it off
and on. Problem is, he's getting a loud pop in the audio when he does so.
The obvious answer, a .01uF cap across the switch, isn't solving his
problem. Suggestions?

Peace,
Paul

More about : switch popping

Anonymous
January 28, 2005 11:26:32 AM

Archived from groups: rec.audio.pro (More info?)

Paul Stamler <pstamlerhell@pobox.com> wrote:
>A correspondent asks the following question: He has a turntable with a
>115VAC synchronous motor; he's using a standard light switch to turn it off
>and on. Problem is, he's getting a loud pop in the audio when he does so.
>The obvious answer, a .01uF cap across the switch, isn't solving his
>problem. Suggestions?

How about an MOV across the switch, or one across the motor? Better
clamping than you'll get from a cap. I am assuming this is an RF
problem and not magnetic leakage from the motor.

A PTO thermistor in series with the motor will limit inrush current and
reduce a lot of that trouble too. Also make the motor last longer.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
January 28, 2005 1:20:11 PM

Archived from groups: rec.audio.pro (More info?)

Paul Stamler wrote:
> A correspondent asks the following question: He has a turntable with
a
> 115VAC synchronous motor; he's using a standard light switch to turn
it off
> and on. Problem is, he's getting a loud pop in the audio when he does
so.
> The obvious answer, a .01uF cap across the switch, isn't solving his
> problem. Suggestions?
>
> Peace,

> Paul

You need a cap bigger then 0.01uF.

Try a 0.1uF in seires with 100 Ohm resistor.

Across the switch is good but across the motor is better.

do a goggle on RC arc snubber

Make sure the audio wiring is well shielded.

Make sure the little ground link from the pickup shell to the audio
ground at the pickup is disconnected (unless the pickup mount is
insulated) and run a seperate ground wire from the turntable chassis to
the amp chassis. You don't want the tt to be grounded to the amp via
the audio cable, you want the TT grounded to the amp via the ground
wire. only!, not both ways or it will make a ground loop. If the
pickup mounting is insulated from the TT ground, then you need the link
to ground the pickup shell.

The best combination is: ground the pickup shell to the amp via ONE of
the audio cables using a little link on the rear of the pickup.
Insulate the pickup shell from the TT. Ground the TT to the amp via a
seperate ground wire.

Do not ground the TT to the amp via the audio cables.


If your lucky, you may reduce it but it may be very difficult to
eliminate all together.



Mark
Anonymous
January 28, 2005 4:20:08 PM

Archived from groups: rec.audio.pro (More info?)

A solid state relay with zero-crossing switching? I thought some of the
turntables could be disengaged from the motor without turning them off.

Bob


"Paul Stamler" <pstamlerhell@pobox.com> wrote in message
news:XGmKd.33665$8u5.5409@bgtnsc04-news.ops.worldnet.att.net...
> A correspondent asks the following question: He has a turntable with a
> 115VAC synchronous motor; he's using a standard light switch to turn it
off
> and on. Problem is, he's getting a loud pop in the audio when he does so.
> The obvious answer, a .01uF cap across the switch, isn't solving his
> problem. Suggestions?
>
> Peace,
> Paul
>
>
!