Bob E. wrote:
Just on this small board there are these extra labels from "s10"
through "s37".

http://www.tinyuploads.com/images/8O0dYH.jpg

What is this "s" designation for?

Looking at the schematic, it might indicate a part whose value changes
(or is/is not installed) based on which version of the board is being
used. Note that parts with the "s" labels don't have a specific value
listed - compare C308, marked just "s14", with C307, marked "1000/25".
Also note that the fuses and transformer all have "s" labels; these
parts often are different for a power supply with 120 V vs 240 V input.
Also, it doesn't make sense to have J301 and Q302 installed at the same
time; J301 would just bypass Q302 in that case. Both J301 and Q302 have
"s" numbers. Somewhere on the schematic or in the manual there should
be a table of "s" number to part number based on the version of the
board.

To your original problem, have you tried unplugging CB304 and measuring
the voltage across +MB and G, or across C307? Those should be pretty
close to 12.5 V DC. If you have a scope, also measure the same place
for AC ripple; if you don't, put your multimeter on AC and measure the
same place - you should have much less than 1 V AC. If there is a lot
of ripple, check C307 and C308.

Matt Roberds