PT Multi-voltage switch wiring options???

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MCK
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PT Multi-voltage switch wiring options???

Post by MCK »

Hi there. A noob question if you don't mind. I have a PT that has taps for various voltages and instructions like twist such & such for 100V, twist the other such & such for 240V etc. Where can I find the appropriate switch to use to make this selection and how do I wire it. I know this can't be hard but I just can't think it through. Thanks for all your help. Most appreciated.
MCK
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Re: PT Multi-voltage switch wiring options???

Post by MCK »

Looked around for this but can't find info & switch configuration to handle the type of flexibility needed. I am thinking of using a simple terminal strip to achieve the connection options when needed. Any issues anyone can think-of?

http://www.grainger.com/Grainger/items/6YJ03?Pid=search
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David Root
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Re: PT Multi-voltage switch wiring options???

Post by David Root »

You seem to be talking about the primary wind of the PT. You can't play fast and loose on that side of the PT. It MUST be connected the same as your wall supply voltage.

You can however do that on the secondary side if the transformer if you have tap(s) on the High voltage winding. Most likely a heavy duty rotary switch, but there is more to it than just switching. Switching without some kind of noise suppression would blow your speakers at high volume.

Generally it should be set up so that any switching is done in off or standby mode.

The one amp I can think of that does this is the old Music Man amps. Take a look at those schematics, It is just a three way switch IIRC, off-lo-hi. It switches between 700V plate and about 500V plate.
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M Fowler
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Re: PT Multi-voltage switch wiring options???

Post by M Fowler »

You can use the Marshall style voltage switching.

http://metroamp.com/store/index.php?mai ... ucts_id=95
MCK
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Re: PT Multi-voltage switch wiring options???

Post by MCK »

I should have been more explicit. I am trying to sort this out for my Lil Devil. Dana posted the PT config for the international iron here :

http://ampgarage.com/forum/download/file.php?id=10871

As you will see, this PT requires some interesting lead combinations to go from 100V to 120 to 220 & 240 etc. As much as I scratch my head and look for products etc best I can come up with is either a 2 switch configuration or a terminal strip based arrangement where I use jumpers to configure as needed.

To David's point, of course this change would be done when amp is off & disconnected from mains. Actually I only will need this change once every few years when I move between continents due to work etc. So I don't need something out on the back panel with ease of use.

Thanks for looking into this question.
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David Root
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Re: PT Multi-voltage switch wiring options???

Post by David Root »

Now I understand, mf is right, that Marshall switch is the way to go!.
MCK
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Re: PT Multi-voltage switch wiring options???

Post by MCK »

Thanks for that guys. I was simply dismissing these thinking they are simple SP3T switches but it appears they are not. We're on the right track. I managed to track a drawing of how the terminals are connected. This is what we're talking about right?

http://www.deepsurplus.com/Speaker-Part ... tch-Modern

So here's the golden question. Is there a similar switch that does 4 voltages rather than 3 like this one? I would like to wire this thing for 100V, 115V, 220V & 240V.

Thanks so much for your help.
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Structo
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Re: PT Multi-voltage switch wiring options???

Post by Structo »

I'm thinking you may have to go to a rotary switch for that.
Tom

Don't let that smoke out!
paulster
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Re: PT Multi-voltage switch wiring options???

Post by paulster »

I've never seen a rotary that would allow you to do multiple voltages on a twin tapped primary transformer, as used in the Lil' Devil.

The Marshall-style ones are for transformers with a single primary and multiple taps, which are great if you're in a 220/240V country, but can suffer sub-optimal performance in a 100/120V country as the transformer will usually sag more under load than anticipated.

I have all of my transformers wound as dual 120V primaries, so I can switch between 120V and 240V, and use this kind of switch:

[img:200:135]http://img-europe.electrocomponents.com ... 884-01.jpg[/img]

which works great for these voltages, as it will put the two primaries in series or parallel, but doesn't give you a huge amount of flexibility.
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