wiring the power supply? for #124

[echo44]

making some more progress,
wiring in the power supply transformer
there is a white and black wire.

Wiring up the typical 3 prong receptor used in most amps
as you look at the back of the receptor facing the soldering lugs
with the middle lug orientated up. is there a convention to which side is considered positive? I have decided the white wire on the transformer will be considered + and the black wire -. So was going to wire the white wire to the fuse and connect the fuse to the positive lug on the chassis receptor which ever that one may be. Does it even matter? Sorry in advance for such a rooky question.

[David Root]

IIRC on the power cord black is the line and white the neutral, so black goes to the fuse. Fuse out to switch. Switch out to black wire on the PT primary. White power cord goes to white wire on the PT primary.

[JazzGuitarGimp]

Yes, there is a polarity to it, but I don't have it memorized. It's easy to figure out though: Look at one of your wall outlets and you'll notice one vertical blade is shorter than the other. This one is the 'hot' wire (the one that goes to your amps' fuse). Now, get a power cord with an IEC connector and use an ohm meter to determine which contact on the IEC end connects to the hot blade on the plug end.

CHeers,
Lou

[amplifiednation]

IIRC I'm pretty sure if you look closely on the IEC, the hot lead is marked "L" for 'live' Wire that to the fuse, then to transformer. The other terminal can be wired directly to the transformer. The transformer primaries are interchangeable.

[JazzGuitarGimp]

Yes, Taylor is right, although I have seen some IEC connectors which do not have identifying marks on them. But if it does have them, L is for Line (the term electricians use for the 'hot' wire in the US, and N for Neutral, which is the term used for the 'cold' wire. In the US, the cold wire is supposed to be the same voltage potential as GND. I say supposed to be, because sometimes a heavy load on a circuit can pull the neutral line a bit above GND.

[M Fowler]

L for load.

[ic-racer]

Not saying it is the best or correct way, but the pictures of #124 and the HRM I built show the fuse on the WHITE wire from the electrical plug. Not the Hot one.

[ToneMerc]

Not saying it is the best or correct way, but the pictures of #124 and the HRM I built show the fuse on the WHITE wire from the electrical plug. Not the Hot one.

For electrical safety standards it is the wrong way, period. The load side should be fused, not the neutral. Just because HAD, Marshall or Fender did it doesn't make it correct way. I see so many builds that are wrong.

TM

[talbany]

Not saying it is the best or correct way, but the pictures of #124 and the HRM I built show the fuse on the WHITE wire from the electrical plug. Not the Hot one.

For electrical safety standards it is the wrong way, period. The load side should be fused, not the neutral. Just because HAD, Marshall or Fender did it doesn't make it correct way. I see so many builds that are wrong.

TM

Mike is correct!!

Tony

124

[Ang3lus]

after all this work it must work !!

[ic-racer]

Follow appropriate electrical codes for your country. Don't do what I do.

Having posted that. On personal TUBE amps that run from my studio ( that I wired with 12g wires, 20a GFI breakers etc.) I fuse the neutral on the primary transformer wiring. I want the load between the fuse socket and the hot line I don't want to be forced to unplug the amp to check the fuse because I might forget to do it! The fuse socket is the only external link to high voltage. All other sources of a shock are INSIDE the chassis. In the event of a 400vdc to ground short inside one of my maps (that theoretically would bypass the fuse), my GFI in the studio will trip.