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Old 20th Aug 2004, 11:00 pm   #1
Radio_Dave
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Default Pilot Little Maestro mains switch

Hi,

I am restoring a Pilot Little Maestro but I don't know what to do with the mains switch. The switch is only single pole and it is switched to the chasis. I am not happy with this but I am unsure what to do.

The ideal thing to do would be to fit a new volume pot and double pole switch but I doubt if I could get one to fit!

What is the best way to wire a single pole switch with an ac/dc set?

Thanks
David
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Old 20th Aug 2004, 11:34 pm   #2
Tim
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Default Re: Pilot Little Maestro mains switch

Hi Dave.
You are quite right.
I (and no doubt most forum members!)would be unhappy about a switched neutral too.
A double pole switch is the best option, but if you can't get one to fit the switch the next best thing is to re-wire the set with the switch in the live lead of the flex, and the existing wires to the switch ,joined or replaced with one length of wire.
Cheers
Tim
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Old 20th Aug 2004, 11:42 pm   #3
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Default Re: Pilot Little Maestro mains switch

Rewiring the live to the switch is a better option but the chasis will always be connected to the negative of the mains supply is this Ok?

There must be a good reason why the designers put the switch to the chasis. I have seen it before in other radios and test gear but I have always been able to fit a double pole switch

David
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Old 21st Aug 2004, 9:33 am   #4
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Default Re: Pilot Little Maestro mains switch

Hi,

Please don't answer my dumb question about why the designers of the day "seemed" to always switch the negative, I've figured it out why they did that myself.

David

Last edited by Paul Stenning; 26th Dec 2004 at 9:01 pm. Reason: Fix link or code for vBulletin
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Old 21st Aug 2004, 10:02 am   #5
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Default Re: Pilot Little Maestro mains switch

Go on then - tell those who haven't figured it out!!!
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Old 21st Aug 2004, 10:19 am   #6
Radio_Dave
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Default Re: Pilot Little Maestro mains switch

In an ac/dc set like my Little Maestro it looks like the negative side of the mains is switched to the chasis. We are forgetting that when this radio was designed it would have had a 2 pin mains plug and although the mains cable may or may not have been colour coded the chasis could have ended up live or neutral depending on which way the plug was put in the socket!

Therefore I guess the designers had no choice but to use the single pole switch to isolate the chasis because they had no control over how the mains plug was plugged in.

Makes sense to me, what do you think?

David

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Old 21st Aug 2004, 10:55 am   #7
mickjjo
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Default Re: Pilot Little Maestro mains switch

Hi, I always thought the neutral to chassis line was switched to prevent the possibility of mains hum being induced into the volume control, or maybe it was just cheaper.....

Regards, Mick.
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Old 21st Aug 2004, 11:12 am   #8
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Default Re: Pilot Little Maestro mains switch

I stand to be corrected I came up with what I did after a good nights sleep and it does'nt explain why they did'nt use DPST switches
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Old 21st Aug 2004, 11:20 am   #9
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Default Re: Pilot Little Maestro mains switch

Probably because they cost more than a SPST switch!

Sam
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Old 21st Aug 2004, 12:21 pm   #10
Paul Stenning
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Default Re: Pilot Little Maestro mains switch

I thought it was for easier wiring. Connect the live incoming lead to the voltage selector and the neutral to the switch. Then for an AC/DC set you just need a short link from the switch to the chassis.

I have moved this thread to Components and Circuits as it's of relevance to many sets.
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Old 21st Aug 2004, 4:19 pm   #11
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Default Re: Pilot Little Maestro mains switch

In the days before the safety police, it wasn't considered necessary to switch both poles even though as has already been pointed out, the mains could arrive 'either way around', still the makers took the cheap option almost every time - but especially with the lower cost sets. If you opt to use the single pole, ensure that the mains cannot be reversed in polarity by fitting a standard three-pin plug - but you would be better by far to fit a new two-pole switched control.
-Tony
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Old 21st Aug 2004, 9:39 pm   #12
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Default Re: Pilot Little Maestro mains switch

A live chassis radio is not safe with a single pole switch in the neutral. Paradoxically, a radio in this condition becomes even less safe when switched off as the chassis then becomes live via the heater chain.

Although a double pole switch is the obvious modification, I’m not at all keen on destroying the originality of these sets. A solution I have adopted is to use a switched 13A plug, fitted with an HRC 1A fuse, which will always break the live connection, assuming that the wall socket is correctly wired. These plugs are available in B&Q complete with integral neon, and also save track wear on potentiometers fitted with a switch.

Regards, Leon.

Last edited by Paul Stenning; 26th Dec 2004 at 9:03 pm. Reason: Fix link or code for vBulletin
 
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