Valencia
Quoted from t3amaw3s0m3:- I eventually decided to use the barrel jack on the mod board, and a wall wart plugged into the utility socket. However, the docs don't mention it's a center-negative jack; I had to figure it out with a multimeter by confirming which pin on the barrel jack connected to ground pins on the RPi. Only having center-positive power supplies (how people usually make them, at least in the US ), I had to re-wire one of mine to reverse the polarity.
Once I overcame the blown fuse and rewired one of my 12V 2A PSUs to be center-negative
It doesn't seem right. The Holomodsp board's power jack has the positive(+) in the center and a negative(-) on the outside of the jack. You can see it in the attached pictures, one of the external power supply that can be purchased as an optional extra together with the kit, on the power supply label you can see the polarity (center to +).
This is important, mainly in kits sold since 2 months ago, since a diode that protected polarity reversal was replaced by an inductor and several capacitors that act as an EMI filter to prevent radiofrequency interference, when the coils are activated, may affect the screen.
Both with the cable included in the kit and with the optional extra power supply, the polarity is always correct. But if someone decides to use their own power supply and connects the polarity reversed, it can irreversibly damage the board and screen.
jack_holo_002.jpgjack_holo_003.jpg
Corfu
Los Angeles, CA
