Power Tranny Input

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Power Tranny Input

Postby codamedia » Sat Mar 21, 2009 1:52 pm

I recently got an old Fender Bandmaster (66') which still had the original power cord. I am replacing that to a three prong cord, based on the diagram at the bottom of this page: http://www.theguitarfiles.com/guitarfile644.html

Old amps used to wire the "neutral to the switch" and the "hot to the fuse". Then to the PT.
This diagram converts the "hot to both switch and fuse" and the "neutral straight to the PT".

ON REVIEWING THE NOTES AND DIAGRAM IN DETAIL I HAVE ONE QUESTION!
Once this is completed, the Primary lines to the power supply are reversed - are they not? Does the PT primary have a "Neutral & Hot" or does it matter. On my bandmaster, both lines are BLACK so I can't really tell, and the diagram seems to say the seem thing.

Regards,
Sean
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Postby TomMcNally » Sat Mar 21, 2009 3:04 pm

Hi Sean -

The power transformer doesn't care about polarity.
Either way is good. The ONLY time it matters is if
you have a 4 wire primary, you need to phase
them properly to put them in parallel for 120 volt use,
and in series for 240 volt use.

The hot (black) to fuse to switch method is the correct
way to do it. That way if the switch shorts to ground,
you are protected. The old way could lead to a shock
if the switch broke down.

... tom
Last edited by TomMcNally on Sat Mar 21, 2009 5:51 pm, edited 1 time in total.
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Postby codamedia » Sat Mar 21, 2009 4:53 pm

Thanks - that makes me feel much better to know this.

Sean
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Postby Geek » Sat Mar 21, 2009 10:28 pm

Actually, to be UL compliant, it has to go to the fuse BEFORE the ground switch.

Putting a 0.01uF x2 safety cap across the power switch also saves some grief for other appliances on the line.

My $0.02

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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