T1040D4RDB remote power and reset

[ronw]

We have a T1040D4RDB board and want to connect to J38 and J39 to allow remote reset and power control.

The power control circuit has inadequate debouncing. I have tried with both a relay and a momentary switch. When the switch or relay closes, the T1040D4RDB starts to power-up. But when switch or relay opens, it turns power back off.

Would adding a capacitor across the switch/relay contacts resolve this problem?

What value of capacitor should be used?

Ultimately, we want to use a Raspberry Pi3 to control the power and reset. The relay board we are using is http://wiki.52pi.com/index.php?title=EP-0099

[yipingwang]

This is how it suppose to work, Whenever the switch or relay closes, the T1040D4RDB will power-up and when switch or relay opens, it will power off.

[ronw]

I tried that, but it doesn't reliably switch the T1040's power.

Also.....

We have 2 T1040D4RDB units. The other unit toggles its power in response to a momentary activation of the relay. If I leave the relay activated, de-activating the relay does not cause the unit to turn off. I have to activate and de-activate the relay, again.

Also, when measuring the voltage across the header pins, I can see that the push-button (on both units) is momentary. That is, the voltage goes to 0 when the button is pushed, then returns when the button is released.

This is as expected with an ATX power supply, which, according to the T1040D4 Reference Design Board Reference Manual, is what the units use.

[yipingwang]

With ATX Power supply it can take few seconds to turn off the board, so you can wait for few seconds (20s) to see if the relay turns off the unit or not. Please go through the ATX power supply specifications for this and also check how to jump start the ATX power supply.
With relay you should measure voltage values when it is activated and deactivated, check how much time it taking to reach zero or maximum voltage.