Author Topic: Polarity Switch  (Read 1951 times)

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Offline 12thfretfire

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Polarity Switch
« on: May 25, 2011, 06:33:57 am »
Does anyone know what the deal with the polarity switch shocking you on the '71 solarus model? im about to add this one to my collection and want to know if theres a fix or if i just shouldn't touch the thing.

Offline EdBass

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Re: Polarity Switch
« Reply #1 on: May 25, 2011, 07:19:33 am »
Touching the switch itself shocks you, or in one f the switch positions you get shocked by other things when you also touch an instrument that's plugged into the Solarus?
What other vintage amps are in your collection, anything else with a polarity switch? Most vintage amps that have switchable polarity (2 prong AC) will shock you under certain circumstances and although many players have dealt with many "zaps" for many years, it's probably not a bad idea to upgrade to a grounded amp.

Offline 12thfretfire

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Re: Polarity Switch
« Reply #2 on: May 25, 2011, 08:47:18 am »
I dont have the amp yet, im just about to buy it and i saw from a review that says "in some circumstances the polarity switch can shock the living hell out of you". Im just trying to figure out if anyone else has had this problem and knows how to fix it or knows if it is just a problem on this guy's specific solarus. I have a sunn beta lead, sunn alpha slave, marshall jtm, and a vintage leslie rotating speaker. None of these amps have polarity switches, so no. And also, what exactly does it do?
thanks

Offline pickinatit

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Re: Polarity Switch
« Reply #3 on: May 25, 2011, 09:18:35 am »
I suspect that what they meant was what Ed Bass was saying.  They don't mean that the switch itself will shock you, but that with the 2 prong chord (not grounded) if you, for instance,  touch your lip (or something) to a microphone while your hand is on your guitar strings (guitar plugged into the Solarus) you might get a shock depending on the position of the polarity switch.

Simple fix is to take it to a tech and have the power chord changed out to a three prong chord = End to the shock problem.

Now if you really do mean that the switch itself shocks you...well, that's another story beyond my realm of knowledge. 

Offline EdBass

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Re: Polarity Switch
« Reply #4 on: May 25, 2011, 09:55:15 am »
Old amps weren't grounded, in fact old AC wiring generally wasn't either so it wasn't an issue.
The polarity switch did exactly that; switch polarity from one side of the 2 prong plug to the other. The same effect as unplugging the amp and reversing the plug in the wall socket, but it's a lot easier to flip a switch on the fly rather than unplug and replug a wall socket.
The reason was to help combat AC induced hum, and to get all the grounds lined up (PA, MI amps) so you wouldn't get "zapped" when you touched one or the other or an actual earth ground. Getting the amp grounded with a modern 3 prong plug is the best answer, and any competent tech can fix you right up.
There are several easy modernization mods that the forum members here have applied to old Sunns; post back if/when you ever actually get the amp.

Offline Walt-Dogg

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Re: Polarity Switch
« Reply #5 on: May 25, 2011, 10:36:18 am »
Now if you really do mean that the switch itself shocks you...well, that's another story beyond my realm of knowledge. 
Considering the switch is plastic...  :-o
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Offline 12thfretfire

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Re: Polarity Switch
« Reply #6 on: May 25, 2011, 01:45:45 pm »
Alright. Thanks everyone. I dont think its that big of a deal if it shocks me anyway. Ive been shocked before by putting my mouth up to a mic and its not bad. If thats no the case i can get it fixed easily i assume. Hopefully i can get it soon and check out how it sounds.

Offline loudthud

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Re: Polarity Switch
« Reply #7 on: May 25, 2011, 04:16:38 pm »
The earliest Smiley Face Sunns did not have a ground switch. Depending on how much leakage current there was from the power transformer, you might get a shock from almost anything. When two or more amps are connected together, the problem grows exponentially. The only sane thing to do is get the amp(s) converted to a grounded mains plug.

Offline EdBass

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Re: Polarity Switch
« Reply #8 on: May 25, 2011, 04:50:29 pm »
Now if you really do mean that the switch itself shocks you...well, that's another story beyond my realm of knowledge. 
Considering the switch is plastic...  :-o

Plastic can conduct electricity, it's a decent insulator but with enough voltage it will. Air can be a great insulator also, think about that the next time you see lightning.  :wink:
Always be careful; don't assume non metal components are safe when high voltage is concerned, nothing is "electricity proof", just like anything will burn if you get it hot enough.
On the other side of that; water is a great insulator, an extremely poor conductor of electricity. Don't drop your amp into your bathtub with you though, it has to be absolutely pure H2O, no contaminants at all, particularly salts and metals or it will light you up like a Christmas Tree.

Offline EdBass

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Re: Polarity Switch
« Reply #9 on: May 25, 2011, 04:54:53 pm »
The earliest Smiley Face Sunns did not have a ground switch. Depending on how much leakage current there was from the power transformer, you might get a shock from almost anything. When two or more amps are connected together, the problem grows exponentially. The only sane thing to do is get the amp(s) converted to a grounded mains plug.

I bought a split chassis from a guy who warned me that it was so "live" that it was almost unplayable. He was right, it was quite sparky. All better now...

Offline 12thfretfire

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Re: Polarity Switch
« Reply #10 on: May 25, 2011, 10:10:46 pm »
i just bought it and it turns out the guy i bought it from had already replaced the ac with a grounded one so im assuming the problem with the switch (if there was one) is solved. Thanks again. :mrgreen:

Offline Rex B

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Re: Polarity Switch
« Reply #11 on: May 29, 2011, 04:02:05 pm »
Getting shocked. Don't assume having the polarity switch in the wrong position will just give you that "little tingle" you get sometimes. I was once playing thru a Music Man amp, and when I went to sing, my lips touched the mic, I saw a blue flash, and woke up on the ground with a bunch of people looking down at me. Flipping the polarity switch solved the problem. The "tingle" we get is normally just a minor difference between the "ground" (white wire) on two different wall sockets. Reverse AC polarity is means the ground on one component is at 120V vs ground on the other: a dangerous and potentially life-threatening situation. (or maybe it is actually 240 V because when one side is at +120V, the other is at -120V. Never bothered to measure it))  Having a 3 prong grounded AC cord was the right solution.
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