Voltage Drop on RaspberryPi B+ [SOLVED]

[Pram]

I hooked up the ATX Raspi to my model b+ pi as explained on the setup page. After starting it the red power led of the pi did not light up and flickered. I tried different power supplies up to 2.1 amps, but the same error occurred. I literally have no clue why this is happening.

[Felix]

Is this your first time wiring up the ATXRaspi?
Could you possibly include a photo that clearly shows the ATXRaspi, the wiring between them, and the button you are using?
Is the button a momentary type?

[Pram]

Yes it's my first time wiring up ATXRaspi.
The button is a momentary switch.
Pictures can be found here https://www.dropbox.com/sh/g4skpgn1smlait1/AADllCREQAQjqGLND2x1WYFka?dl=0

[Felix]

Thanks. Both wires are white so I can't tell which goes where.

This gentleman had similar issues with his ATXRaspi, and I explained how to debug if he has a good ATXRaspi or not:
https://lowpowerlab.com/forum/index.php/topic,637.0.html

Please read this thread first. I assume you followed the guide given here: http://www.lowpowerlab.com/atxraspi
Please also confirm your shutdowncheck script is running

[Pram]

Yes I followed the guide and I can power on/off the raspberry pi using ATXRaspi. The only thing is that the red power led on the pi does not light up or flickers.
The wires are connected as explained in the guide.

[Felix]

When does the RED LED not light up?
When does the RED LED flicker?

Finally .. when do you expect it to light up?

[Pram]

Normally the red power led on the raspberry pi should not blink at all and should stay on, because it indicates the 3.3 volt coming from the regulator on the pi, which is hooked up to the 5volt usb input.

In my case the red led does not light up during boot and flickers when the pi is booted.

[Felix]

Can you measure the 3.3V rail on the Pi? What is the voltage on that?
How about the output voltage from ATXRaspi?

Other than the LED "behavior" is there anything wrong?
Sounds like ATXRaspi is working, unless there is a big power drop, I don't think there should be any issue.

[Pram]

I'll measure it in a second, but normally there should not be any power drop and the led should never turn off.

[Pram]

During boot the power of the 3.3 volt rail drops down to 1.8 then stays at 2.5 and at the end goes back up to 3.3 volts.
The 5 volt rail drops down from 5.2 to 4.8, but goes back up to 5.0 and stays there.
The ATXRaspi constantly outputs 5.3 volts during boot.
Without ATXRaspi I measured the on the 5 volt rail constantly 5.27 volts and on the 3.3 volt rail I measured constantly 3.8 up to 3.3 volts

[Felix]

The absolute max voltage you should ever feed into an ATXRaspi is 5.5V. If your power supply ever spikes above that it could damage the components on it and cause malfunction.
Without the ATXRaspi you said you are reading 3.8V on the regulated 3.3V rail? Something sounds wrong about that, it should be at 3.3v tops.
Do you have a model B (non +) to try it with?
I am not convinced there is anything wrong with the ATXRaspi, but rather something is going on with the power supply or your Pi. If voltage doesn't drop below 4.5V on the ATXRaspi then I am not concerned about it.

[Felix]

One question - did you source the USB cable from my shop?

[Pram]

Without the ATXRaspi you said you are reading 3.8V on the regulated 3.3V rail?

I am sorry I meant 3.28 up to 3.3 volt

Do you have a model B (non +) to try it with?

No I dont

[Pram]

I also got that feeling that my Pi is messed up, but I am getting a new one asap and try the ATXRaspi on the new one, that I am going to get tomorrow.

[Pram]

I got my new Raspberry Pi B+ today and everything worked fine with ATXRaspi. So thanks for your support Felix