Can I convert a stereo receiver's hard-wired two-prong power cord to an IEC C7?

Question

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Repairs to my stereo receiver require considerable disassembly. One step requires me to unsolder the two mains leads from posts on the main circuit board. (the polarized, two-prong plug, AC cord enters through a strain relief bushing on the back panel.)

I'd like to change this setup to an IEC receptacle (C7, polarized), but I'm hesitant since everything I've read says they are for low-power home appliances.

Is such a setup OK to use on my late '80s, 80 W per channel receiver?

Answer 1

I will add my own answer for completeness sake.

The amplifier is an US model. It has an ungrounded polarized plug, and according to the schematics, it has polarized ungrounded outlets for other devices and a leakage resistor between Neutral and the ungrounded metal chassis.

Therefore preserving the polarity of Live and Neutral is very important, so unpolarized mains couplers are out of the question.

The polarized C7/C8 couplers are non-standard, and the polarization may not be standardized, and the polarized inlet on a device accepts a non-polarized coupler, it will not preserve the polarity if someone uses a wrong unpolarized cable.

Therefore, it will be unsafe to change a fixed polarized mains cord to C7/C8 couplers, even polarized ones.

Answer 2

Yes. One of the pins is identified probably wider. use your ohm meter and determine which terminal it is soldered to. When you install the new cord do the same thing in reverse. If the existing cord does not have any polarization on the plug just connect it.

Answer 3

IEC C7 handles something like 2.5A at 220V or 10A at 120V. This should be enough for everybody(c).

In 120V world, 10A amount to 1200W total power.

The "150W power consumption" tag hints that you are well within the 1200W limit and also hints that it is not exactly 2x80W either.

In 230V world, 2.5A will get you somewhat below 600W - still more than enough for your 150W needs.

Answer 4

OK, this is more detective work than it's actually worth, but let's give it a shot:

• We're dealing with a US-American appliance, so 120V
  • The power cord looks bifurcated – which would be very untypical for the European market for the late 80s/very early 90s (which is the era that the manual's font suggests)
• This is a Sony device
  • because it recommends Sony batteries and a sony-specific remote control family
• This cable carries up to 10A, and one really has to dimension for that continuous current
  • the manual says "2 switchable AC outlets", so no matter how low the power consumption of the receiver itself is, we cannot risk it starting a fire later on
  • the cable says "AWG18", also suggesting the 10A are expected
  • at 120V, the rated 150 W power (however you end up with a 2×80W output rating with less than 160W input rating… marketing) would be only a bit above 1A, but the fact that there's additional outlets really is the game changer here: saving money on the supply plug might start a fire later on.

My best bet is this is the Sony STR-GX 5 ES, as that has the right amplifier output power claim, and was manufactured 1988–1989.

That all in all says that you can do this with a plug/cable combination actually rated for 10A – but as others have said, the IEC C7 is officially only rated for 2.5 A, and the polarized version of it is proprietary. So you need to check with the vendor of said plug, and said cable, that you actually get something tested and rated for 10 A. That has downsides: you or someone else might later on just use a cheaper cable, which then could potentially pretty hot.

I'm by no means an expert in North American appliances, so, I don't know whether there's feasible alternatives to a polarized modification of IEC C7; if you can, I'd try to get IEC C17/C18 – but I'll be honest, as a European I can remember but a single device in my whole life that had that plug. C18 has the advantage that you can plug in the very ubiquitous C13 cable.