switching power cord leads

[islandamp]

I'm rebuilding an old Filmosound amp that has the power switch and fuse on the neutral side of the incoming power, before the transformer. Any problems with just switching the power cord leads, on a new 3 prong cord? Seems like the phase of the transformer would be reversed, but it runs to a 5e3 rectifier, so maybe it would be ok. Better safe than sorry. Thanks.

[sluckey]

This is how I like to wire the primary circuit...

[shooter]

the phase of the transformer would be reversed

single phase systems don't have a phase, they do have a reference to ground.
you're also converting to DC, so no phase issue.  now if it was 6-phase rectified to DC, you wanna get that correct

[JPK]

I would just wire it as Slucky shows. Put the fuse and switch on the line side. Neutral direct to tranny.

[islandamp]

The old amp is wired as Sluckey shows, except the fuse and switch are on the neutral side. Is it ok to just switch that wire with the hot wire?

[PRR]

> the fuse and switch are on the neutral side.

That is not a problem. You can still get shocked "downstream" of the off switch, through the transformer.

IMHO, it worked for 66 years, why change now? Did you get it from a coroner's evidence locker?

[sluckey]

The old amp is wired as Sluckey shows, except the fuse and switch are on the neutral side. Is it ok to just switch that wire with the hot wire?

yes

Sometimes a word is worth a thousand pics. 

[islandamp]

Thanks

[JPK]

The old amp is wired as Sluckey shows, except the fuse and switch are on the neutral side. Is it ok to just switch that wire with the hot wire?

The old amp is wired as Slucky shows, except it is not. 


Leaving it as is makes much more sense than swapping the power cord leads.

[bmccowan]

Leaving it as is makes much more sense than swapping the power cord leads

"leaving it as is," is not likely a good option. But it might depend on the model Filmosound. The 179, the one I am familiar with has 3 power input leads. But one is not a safety ground; one is common (black) one feeds a lamp circuit in the PT (black & yellow) and one is the amplifier hot lead (black & red.) Indeed, B&H put the fuse and switch on the common - likely because of the two hot leads. What I did was I replaced the non standard power jack with an IEC. I taped off the black & yellow, connected the (black & red) to the fuse & switch, and connected the common (black) to the neutral on the IEC - same as sluckey suggested and of course grounded the safety ground to the chassis. I think this is the "correct" way given modern household circuits and a PT that will have an unused input lead. And I am still alive enough to write this post. Other model Filmosounds may vary.

[acheld]

If you are changing the power cord to a modern "3 prong" style, why would you not wire it correctly (as in Sluckey's diagram)??

Of course it will work fine with the switch and fuse wired into neutral, but what about the next technician who services the unit?  Or worse, the next owner who has watched one Uncle Doug video and tries to mod the unit herself.   

Some things should be done right. 

[islandamp]

Exactly why I asked. I am switching the hot and neutral to get the fuse and switch on the "hot side" I learned many years ago to never switch or fuse a neutral. My question was, will any shock hazards occur from switching the new power cord hot to the "bottom" of the transformer, as shown in a schematic view, and moving the neutral to the top., therefore putting the fuse and switch in the hot line. Just reversing the polarity of the transformer really. I've had issues in the past with touching vintage amps and effects or microphones before. I will wire in a 3 prong cord this week.

[sluckey]

You're really overthinking this. Just do it. No trons will be harmed or set free.   

[JPK]

Leaving it as is makes much more sense than swapping the power cord leads

"Leaving it as is makes much more sense than swapping the power cord leads" is not likely a good option. But it might depend on the model Filmosound. The 179, the one I am familiar with has 3 power input leads. But one is not a safety ground; one is common (black) one feeds a lamp circuit in the PT (black & yellow) and one is the amplifier hot lead (black & red.) Indeed, B&H put the fuse and switch on the common - likely because of the two hot leads. What I did was I replaced the non standard power jack with an IEC. I taped off the black & yellow, connected the (black & red) to the fuse & switch, and connected the common (black) to the neutral on the IEC - same as sluckey suggested and of course grounded the safety ground to the chassis. I think this is the "correct" way given modern household circuits and a PT that will have an unused input lead. And I am still alive enough to write this post. Other model Filmosounds may vary.

You only used half of my quote when you manually re-quoted it. I fixed it. 
I'm with Slucky on this one.