How to save a no-power LP Alpha (maybe Delta) if using USB-C

userHead anonymous 2019-05-28 06:06:41 3924 Views4 Replies
The other day while I was just checking (but not modifying) with the BIOS setting ,
my Alpha board at that time was powered by a USB-C PD 2.0 "15V 3A "power supply, my home's AC power was disrupted briefly.

After AC power resumed few minutes later, I found my Alpha is as cold as a dead boat anchor. No Red, no Blue LED lit up whatsoever.
This is the symptom many had reported in the past.

Is my Alpha really dead? Is my USB-C power supply dead as well?

Luckily I have the USB-C power meter/debugger (WEB-U2, a $35 testing device) I know my USB-C power supply is good, and indeed it negotiated with the Alpha board with 15V being supplied to Alpha. But pressing the power button won't wake the Alpha up. The LEDs (Red and Blue) are all dim.

Again, luckily, I have the DC 12V cable to supply the Alpha as the alternate arrangement.
By using the DC 12V powering method, the Red and Blue LED come alive. Pressing the power button can indeed power the board up. All is (almost) good.

Now the burning question is... is the USB-C powering section of the Alpha board dead? (I have both the USB-C and DC 12V alive, both trying to supply power to Alpha.)
The answer is it is not. At this point, I can remove the DC12V power and let USB-C power adapter continue-n-resume powering my Alpha. And indeed it can.

So....
The act of using DC12V to power the Alpha fixed whatever that is messed up on the USB-C side of the circuitry. May be it (probably USB-C controller) was stuck at a state which needs its butt kicked once.

That act works. Now I can completely remove the DC12V part of powering scheme out of the equation and back to my normal "powering thru USB-C PD power adapter" routine.
(The first time just by using the USB-C power alone, it may take a minute or two to see Red LED comes on and Blue LED blinking. It is normal. It only happened one time.)

So, in the end, the DC 12V powering save the day. DIY in next post.