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Is it possible to modify a soft-power button? Answered

I'm not sure if this is the correct place to post this (apologies if its not)....

I have a small stereo receiver (Lepai S-60) that I use to power speakers in my kitchen and it works well, but the stereo requires that I press the power button on it or the remote every time I want to turn it on.  I was hoping to hook it up to a WeMo switch so that I could turn it on/off via Google Home, but the fact that its a soft power button means that even if the switch turns on or off, the radio doesn't remember what state it was in last.

Is there a way to modify the circuit board so that the receiver is always on and thus, I could control it via the WeMo switch?

Thanks in advance,

Tim

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Hello Tim

The reason why i asked you for the pic is to just understand which type of switch is used in the setup. Looking at the blue head switch i think its a momentary push botton with self locking. ie it should remain in the on position when pressed once and should turn off if pressed again. But from your first comment you said that it doesnt recognize the previous state which it was in and thus its a little confusing for me coz these switches do remember the previous state. Just short the pins and see it works fine or not there is no harm in doing that. You know which pins to short right?? If you are not sure see the pin configuration from internet or you could even use a multimeter's continuity function to identify the pins. if shortning the pins still dont remembers the previous stage of on or off do let me know

Your asked that is there any option to do it on the brown board itself and the answer is no coz the power is first fed into the amplifier board ie the brown board and it is from this board that the power is supplied to the receiver through that white wire. That push button is only used to turn on the receiver and not the amplifier i.e brown board, so just altering the brown board wont deliver power to the receiver board and thus wont work that way.

Regards

Adhith

I had a chance to mess around with it a little more this weekend and I'm a little stumped. The button is definitely a momentary push (not meant to lock). If I unplug it, hold the power button down, and plug it back in, it doesn't come on. I believe the system is looking for the change in state of the button, which means, even shorting it won't work....

I'll mess around with it more next weekend, but I'm open to any suggestions.

Thanks

Tim

OK its clear now. So the arrangement in your setup is called a latching circuit where the momentary power button is associated with a transistor (usually a MOSFET) which in turn switches the circuit. Its actually tough to alter this configuration to simply supply a voltage and run it since we are not sure what type of configuration is used in these circuits. But you can try using another circuit called "one shot switch"(it usually uses a 555 timer) which could act as a switch for few seconds and then turn off in place of the momentary switch but I haven't used them practically. You could do some research on it.
Regards
Adhith

hello Tim

I think this place is perfectly fine to deal with your topic. So understanding what you have written i think you could just wire the WeMo switch parallel to the soft power button and it works fine. I haven't worked with WeMo but i think its just a wireless relay circuit with opto couplers ,also i have no idea with what your switch is like and the connection. if you could help me with much more details and pics i guess i could try my best to help you.

Thanks for the quick response! I'm hoping to modify the amp so that it is always on. I'll then hook it up to the WeMo switch so that I can turn it on and off that way.

In any event, I had a chance tonight to open it up and take some pics.

If I understand the concept, the power button on the front, when pressed, completes a circuit that somehow toggles the power on/off. So can I just short the pins on the back of the circuit board? Or is there a way to accomplish this on the brown circuit board?

Thanks!

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