2-pronged IEC connector on Sunfire Cinema Seven amp?

[amadeuswus]

Hello,
I am wondering if my Sunfire Cinema Seven amp (thanks Craigslist!) might have been modified, and if so why.... The IEC connector has two prongs rather than the usual three. (The prong that would sit forward of the pair of parallel prongs isn't there.) The User's Manual has several sketches of the rear panel clearly showing a 3-pronged IEC connector.

Not knowing what to expect, I attached a 3-pronged power cord (not by First Run Copper). As soon as I connected the cord (amp power off, rest of the system connected), I heard a slight hum from the amp casing itself. (There may be some slight hum/hiss from the speakers, but it's not obtrusive.) The amp plays music without obvious issues and runs cool as I expected from this design.

Is it unsafe for me to run the amp with a 3-pronged power cord? If it's unsafe, should I go to Monoprice to find a particular 2-pronged cord?

And if the IEC connector has been swapped out, why would someone do this? (I do have another component, the Yamaha network receiver reviewed by Amirm, that comes with a 2-pronged connector and power cord, https://www.audiosciencereview.com/...ds/yamaha-r-n803-smart-receiver-review.13830/, but I don't know the reason for this choice.)

Thanks for your thoughts.

 

[egellings]

If there is no ground prong on the amplifier's receptacle, then the third connection on the cord would not contact anything. How could that make any difference? I would have the amplifier repaired to restore that connection for safety's sake.

 

[amadeuswus]

Thanks for your reply. I am tempted to try the 2-prong cord that came with my Yamaha r-n803. (In the Amirm review linked in my original post, it's noted that "this is 2-pin, insulated device"). Can anyone advise whether using the Yamaha cord would be a safe thing to try in these circumstances?

 

[egellings]

It's not the cord that would be unsafe, it's the amplifier with the missing earth ground terminal that would be unsafe should it develop a dangerous internal electrical problem. The amplifier will perform equally well with a 2 or a 3 wire cord; it' just a safety, not a performance issue.

 

[XpanD]

If there is no ground prong on the amplifier's receptacle, then the third connection on the cord would not contact anything. How could that make any difference? I would have the amplifier repaired to restore that connection for safety's sake.

The connection doesn't seem to be there on a lot of the pictures I'm seeing, either. Might have been designed to be used this way, with the extra pin on some models being a regional thing or the like?

Guessing the slight hum coming from the amplifier is a transformer, which shouldn't be of any concern.

 

[NTK]

Is this your amp?
https://hometheaterhifi.com/volume_10_4/sunfire-cinema-seven-power-amplifier-11-2003.html

The picture of its back showed a 2 pole power connector (i.e. no earth ground).

 

[amadeuswus]

It's not the cord that would be unsafe, it's the amplifier with the missing earth ground terminal that would be unsafe should it develop a dangerous internal electrical problem. The amplifier will perform equally well with a 2 or a 3 wire cord; it' just a safety, not a performance issue.

Just to clarify my original post, the IEC connector on my Sunfire amp doesn't seem to have a broken or removed ground prong; the recessed area of the connector is smooth where that third prong would normally be. Because the pictures in the manual show a 3-pronged connector, I wondered whether someone modified this amp (and why).

 

[egellings]

There are appliances that are so-called double-insulated with respect to the power line, and these may not be required to have the additional ground connection, and they can have all the proper UL and CE approvals.

 

[amadeuswus]

Is this your amp?
https://hometheaterhifi.com/volume_10_4/sunfire-cinema-seven-power-amplifier-11-2003.html

The picture of its back showed a 2 pole power connector (i.e. no earth ground).

Thanks, my amp is the standard version of the amp in your link (only 200w/channel vs. 400w in the Signature model). But it's interesting to see the photo of the rear panel. Maybe the manual doesn't match the actual product for my region (US).