Measuring the power used by a kit

 One thing that I try to include with kit docs is some kind of minimal troublshooting file, for example:

http://wb9kzy.com/bugde3di.txt

Basically the diagnostic file asks the builder to do three things:

1) measure the power supply current
2) measure the pin voltages of the PIC chip (usually a PIC chip is on board the kit)
3) measure the resistance to ground with the PIC chip removed from the socket and power disconnected

I always point builders to this file and also ask for a closeup picture of the top/bottom of the board.

But one thing that builders rarely do is to measure the power supply current.  I can understand why, especially if unsoldering is required.  Now if the kit is powered by a 9V battery it's very easy to just connect one snap of the 9V battery and then use a DVM to make the other power connection and read the current.

Why measure the power supply current ?  I have mentioned this before:

https://wb9kzy.blogspot.com/2022/06/two-ways-to-make-kit-easier-to-fix.html

Basically CMOS device like a PIC (as I use them) is either active or sleeping.  Everyone knows how to switch stuff off on their phone like bluetooth or wifi and it saves power.  That's the beauty of CMOS.  Actually at one time (not sure if this ever caught on) this was proposed as a way to test CMOS chips, if the chip clock is stopped the current used by the chip is essentially zero.  If there are any faults on the chip the current will be measurably higher.

This is also true with a kit.  If the PIC is sleeping, the current used should be almost zero, just a few microamps. But if there is a short on a PIC pin, the current will be much higher.

But builders never do the test unless I ask repeatedly.  They often want to buy another PIC chip, it's easy to yank and replace with a socket.  But it's almost never the chip, usually soldering is the problem.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm