16 May
2008
16 May
'08
12:35 p.m.
Right, I've now multimetered the voltages, and:
The 12v line is running at 12.74v
The 5v line is running at 5.40v
I didn't check the -13v line
I took readings from a couple places: Straight off the PSU plug, and in the
case of the 12v, at the monitor plug.
I wasn't sure about the 5v; I took a reading across each of the 8132 chips,
getting 4.14v and 4.16v; but I guess those may not be meaningful as the chip
itself will be taking some of that power.
Hang on, are you saying you're getting 5.4V at the output of the PSU and
4.16V across the power and ground pins of a chip on the logic board?
The fact that the ship is drawing current _should be_ irrelevant. The
voltage is being droppead across the impedance of the supply connections
(wiring, connectors, PCB tracks) betweem the PSU and chip, and that
impedance should be low enough not to drop 1V or more.
And that could well be your problem. A high impedance (relatively) supply
or ground connection can cause 'intersting' voltage drops when anything
starts drawing current. And that'll lead to things not working.
-tony