little-al
Active Member
Well, during the rehab of my FM-50 tuner and 30-A amplifier, I found the original cord on the 30-A has a very tempermental and intermittent short.... very intermittent ....... :dammit:
I spent an hour trying to track down why I had 50+ VAC on the chassis that would come and go only when the amplifier was oriented a certain direction :scratch2:
......... anyway, it turns out the cord, which is in great shape externally and cosmetically, clearly has an internal fault that has only showed up now after months of tinkering. So it needs to be replaced. No big deal, but a shame since it had the original cord.
I've read several threads here at AK and elsewhere about the options of changing to a grounded connection or replacing the old cord with a new polarized zip-cord. I plan to do the latter.
What hasn't been clear, at least to me, is what orientation the new polarized cord should present to the circuit.
I've also read quite a bit about the original non-polarized plugs and how they were meant to be "flexible" in the orientation one could plug them into outlets of the time period so as to allow one to find the orientation that produced the least hum.
What I wonder is, although this flexibility was inherent in the non-polarized plug design, if in fact the "mystery" of which orientation produced the least hum wasn't actually a mystery to the component builders. I wondered if the design of the component itself always assumed that the correct orientation would present the hot leg and neutral leg to the circuit one correct way, and the real "mystery" was always the time period non-polarized sockets which may or may not have the hot and neutral legs clearly identified.... so flipping the plug to find the orientation with the least hum (or putting a meter on the outlet) was the only way to find that correct orientation.
So.... this assumption leads me to believe that when I install the new polarized cord that the hot and neutral legs of that cord should be connected to a very specific part/orientation of the power circuit in the 30-A.
I have my theory on what that would be, but I thought I'd just as the experts.
With that synopsis, my question: Which part/orientation to the power circuitry should I correctly connect the hot and neutral legs of this new polarized cord when replacing the old non-polarized cord?
Thanks!
Al
I spent an hour trying to track down why I had 50+ VAC on the chassis that would come and go only when the amplifier was oriented a certain direction :scratch2:
......... anyway, it turns out the cord, which is in great shape externally and cosmetically, clearly has an internal fault that has only showed up now after months of tinkering. So it needs to be replaced. No big deal, but a shame since it had the original cord.
I've read several threads here at AK and elsewhere about the options of changing to a grounded connection or replacing the old cord with a new polarized zip-cord. I plan to do the latter.
What hasn't been clear, at least to me, is what orientation the new polarized cord should present to the circuit.
I've also read quite a bit about the original non-polarized plugs and how they were meant to be "flexible" in the orientation one could plug them into outlets of the time period so as to allow one to find the orientation that produced the least hum.
What I wonder is, although this flexibility was inherent in the non-polarized plug design, if in fact the "mystery" of which orientation produced the least hum wasn't actually a mystery to the component builders. I wondered if the design of the component itself always assumed that the correct orientation would present the hot leg and neutral leg to the circuit one correct way, and the real "mystery" was always the time period non-polarized sockets which may or may not have the hot and neutral legs clearly identified.... so flipping the plug to find the orientation with the least hum (or putting a meter on the outlet) was the only way to find that correct orientation.
So.... this assumption leads me to believe that when I install the new polarized cord that the hot and neutral legs of that cord should be connected to a very specific part/orientation of the power circuit in the 30-A.
I have my theory on what that would be, but I thought I'd just as the experts.
With that synopsis, my question: Which part/orientation to the power circuitry should I correctly connect the hot and neutral legs of this new polarized cord when replacing the old non-polarized cord?
Thanks!
Al