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Attaching 3-way plugs to 500-C 2-way rear outlets

thornev

thornev

Super Member
As you may know, 500-C rear outlets are only 2-pronged. I want to have my subwoofer powered on when I power on the 500-C, but my sub has a 3-pronged plug. Are there any options to achieve what I want? Maybe a 2-prong power strip that accept 3-prong plugs? (though I can't imagine that that would be safe) Can the ground on a 3-way plug be connected to the 500-C chassis ground? I wonder if that option would be safe only if I altered the 2-prong 500-C cord to a 3-way grounded plug? Although if I were to do that, would I connect the 3-way ground prong to the 500-C chassis ground? (I'm sure there is a thread somewhere on how to alter to a 3-way)
 
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Some subs have standby/auto-on when they see an input signal. Presumably yours does not?

If i were concerned with maintaining ground integrity, yet not modifying the equipment itself, I'd build a relay switch box. Use a small wall wart plugged into the aux outlet, that then energizes a relay to power up the sub. Build in a project box with grounding power cord and grounding receptacle for the sub.
 
who - I don't have the electrical smarts to build what you recommend without step by step instructions. My sub is supposed to have an audio sense to power up, but apparently that only works for the LINE IN. I use the SPEAKER IN because the LINE OUT of my 500-C (RCRDR) is not active for all the switch selections.
 
In that case maybe a "smart" power strip would be a consideration.

They sense current drawn by a primary connected device, would be the 500-C in this case, and then switch on the other outlets in the strip that would power up the sub.
 
Privately I was informed that nothing that draws significant current (such as a subwoofer) should be connected to the rear outlets. Risk of burning out the power switch could occur I'm told. So that is that. I'll keep the sub on a separate wall outlet. It's not a major inconvenience.
 
thornev said:
Privately I was informed that nothing that draws significant current (such as a subwoofer) should be connected to the rear outlets. Risk of burning out the power switch could occur I'm told. So that is that. I'll keep the sub on a separate wall outlet. It's not a major inconvenience.
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With a smart power strip that would not be the case. Nothing would be connected to the aux outlet.

Probably $20 give or take.
 
If you do use a 2 way prong plug in into the back of your Fisher tube anything remember both blades must be small blades. I just don’t think it’s worth plugging anything in. Most subwoofers do have on/auto/off toggle switches but if not you can have both your receiver and subwoofer plugged into a good sure protector power strip with both units on and turn them both on/off at the same time.
 
Something like this is what I think whoaru99 is talking about. When you turn on the Fisher, the power strip senses the current and then turns on the other outlet that the sub is plugged in to.

Smart Strip ECG-7MVR Energy Saving Surge Protector with Autoswitching Technology, 7 Outlet https://a.co/d/9rXZzc0

Not saying this is the best one available. Just the first one that popped up when I searched "Smart Strip".
 
I was thinking and could use a power bar that uses the switched AC outlet from the back of a stereo receiver or amp to operate a relay to control the outlets. Especially useful on a receiver that has a remote controlled power on/off and you want to use other amps or gear that draw a sizeable amount of power. Or if you have more than one device that you want switched AC for because usually you only have one switched outlet on the back of your receiver. It’s possible that it’s been designed and sold but do not think I have ever seen one.
the power bar would use a grounded three prong plug and receptacles/outlets but the AC control from the stereo/receiver would be a two prong plug and only draw enough power to operate the AC coil on the relay. It’s possible to use a triac instead of the relay to draw even less power but that adds more components
Probably easy enough to modify an existing power bar to perform the task. Use a chassis or flange mounted AC relay. Power bar would need some open space to place the relay internally and room to re-wire.
 
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Thanks, All. I plugged the 500-C into the same power strip that powers the sub and I leave the 500-C on/off switch in the ON position. The power strip is powered by 110 VAC which is what the 500-C was designed to accept when it was manufactured back in the 60's. I installed a relay in the 500-C long ago to reduce the current coming into the unit when the power is turned on. I'm all set. I'm not crazy about leaving the 500-C in the ON position, but I think it will be OK since I have the relay before the power switch.
 
If I had your sequential power switching desires, for what I`ve read from your post, like has been suggested, I would, like I`ve been successfully doing for over ten yrs. using surge/spike protected smart/green outlet strips on all 7 of my house`s 7 room`s A/V systems that turn on ancillary electronics when the master device is switched on, thus turning the slave devices on ~5 seconds afterwards at powerup, and then ~5 seconds after the master controlling device is turned off.

I get the safe power sequenced on/off desired control along with powerline surge/spike protection for all electronics plugged in to the strip. My smart strips are rated at 15 amps and the slave outlets are relay switched on and off, as I can hear it click when turning on/off the master electronic device.

Using the 500-C`s relay actuating power switch on or not to engage the system is optionally your call, thornev
 
Bill - Not sure I understand what you're suggesting. My 500-C has an internal relay (plus a CL-80 thermistor) that takes the current hit, protecting the on/off switch. Are you suggesting adding additional external relays somewhere?
 
thornev said:
Bill - Not sure I understand what you're suggesting. My 500-C has an internal relay (plus a CL-80 thermistor) that takes the current hit, protecting the on/off switch. Are you suggesting adding additional external relays somewhere?
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I`m saying buy a smart outlet strip (the ones with a single master outlet and a handful of what are called slave outlets that are switched on say 10 seconds after whatever that is plugged into the master outlet is turned on !

My mention of a relay was not meant to confuse you, I was indicating that my Belkin smart outlet strips use a internal relay for their slave outlet`s on/off control instead of using a SS switching device instead.

All you have to do is purchase a quality surge/spike protected "smart outlet strip", then plug your 500-C`s power cord`s plug into the smart strip`s master controlling outlet, then plug your subwoofer`s power cord`s plug into one of the smart outlet`s slave (controlled outlets) then plug the smart outlet strip into a grounded outlet in the room where your stereo setup is, then turn on the powered subwoofer, so when you turn on your 500-C it will powerup itself up and in a few seconds, your powered subwoofer that is plugged into the smart out strips slave controlled outlet will become powered up, and when your through using the stereo system just turn off the 500-C and the smart outlet strip will turn off your powered subwoofer after a handful of seconds.
Straight forward and easy peasy to implement the powering up and turning off control of your powered subwoofer and surge/spike protecting the 500-C and the SS subwoofer`s power amp.

I hope that you`re able to grasp this explanation for a simplified subwoofer power up/down configuration to do what you wish to do, if not ,maybe someone else on A/K can do a better job of doing so.

Good luck with your setup, thornev.
 
Ah yes, Bill, I believe I get it now. I had no idea that such strips with (slave) delayed internal relays exist. But I will go look. Thanks for clarifying. Thorne
 
thornev said:
Ah yes, Bill, I believe I get it now. I had no idea that such strips with (slave) delayed internal relays exist. But I will go look. Thanks for clarifying. Thorne
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That's what was suggested earlier in post #4, a "smart" power strip.

A relatively inexpensive example has been linked by a couple folks in earlier posts.
 
whoaru99 said:
That's what was suggested earlier in post #4, a "smart" power strip.
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The question that just about everyone who has reviewed these power strips is how much voltage and/or current is required by the master controlling device in order to power on the controlled devices. Almost all the reviews are from frustrated customers who find their controlling devices are not delivering enough "juice" to control the slave devices, or the devices are powered on, but they turn on and off seemingly randomly. I've asked that very question of one of the "smart" device sellers I found.

EDIT: I've measured the current my 500-C draws when I first power it on. I forget the amount, but as you probably know, it's not very much.
 
thornev said:
The question that just about everyone who has reviewed these power strips is how much voltage and/or current is required by the master controlling device in order to power on the controlled devices. Almost all the reviews are from frustrated customers who find their controlling devices are not delivering enough "juice" to control the slave devices, or the devices are powered on, but they turn on and off seemingly randomly. I've asked that very question of one of the "smart" device sellers I found.

EDIT: I've measured the current my 500-C draws when I first power it on. I forget the amount, but as you probably know, it's not very much.
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200W, give or take, yeah, isn't huge in the big picture.

That said, it is an amount that should not be a challenge to detect on/off. The specs on that linked in strip says control trigger is 16-30 watts. Detecting 200W of the 500-C seems pretty definitive in that regard.

And, yes, there are some low rank reviews but scanning several I think the bigger issue isn't the strip itself as much as some people didn't really know what they bought and/or how to use it.
 
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