I'm currently setting up my new power supply for Pi. Previous was a 1A USB phone charger and everything worked as it should. However, with my new power solution I get delayed keystrokes, missing keystrokes and sometimes keyboard doesn't work at all.
I'm using AC/DC 19V 3.42A notebook PSU connected to the Pi through LM2596 step-down converter. Step-down converter lowers 19V down to 5V and it's rated 2A. With this setup, Pi is booting but there are some problems with keyboard. I measured TP1-TP2 voltage and it's about 4.3V with SD, keyboard, HDMI and ethernet cable plugged in. When booting it's about 4.9V at the beginning but after few secs it drops to 4.4V and then 4.29V and stays at this level. I measured the voltage also with SD card and HDMI only and it's about 4.41V.
Pi in its off state has 0.91V across TP1-TP2 with HDMI connected and 0.46V without HDMI. This is with keyboard and ethernet cable.
Without ethernet cable and keyboard numbers are respectively 1.54V(!) and 0.39V. I reconnected eth and keyboard and it still was 1.54V, but after power on/off cycle it did go back to 0.91V - I guess it's the capacitor(?).
The step-down converter I'm using is: http://www.aliexpress.com/store/product ... 38263.html . I set the voltage to 5.1V on it and measurement confirms that voltage - it's stable even at the boot time.
What could be wrong with this setup?