"Danny D'Amico" wrote in message ...
On Sat, 23 Nov 2013 08:20:19 -0700, Tony Hwang wrote:

Have you ever worked on car charging system and battery?

Yes. 13.8 volts is "normal" for an open-circuit voltage.
The voltage is highest after charging, and then goes down, over
time, depending on the type of battery.

If I were you I'd replace x-former and battery and start from there.

I have no qualms about replacing stuff, but, I am trying to
debug first, *what* needs to be replaced (other than the transformer,
which is on order).

Right now, I'm trying to figure out why the power supply board
has 0 volts across the PWR and GND pins, even with 13 volts at
the inputs.


The transformer is obviously dead. Replace it immediately. This
will at least let you know if the system will work with the transformer
functional. Step two would be to figure out what is wrong with
the battery back-up. Have you checked for fuses, yet?