I was given a Hercules XPS 2.140 Slim speaker system. The owner purchased it
new from Amazon and it never worked. It sat around longer than the return
period so I inherited it. The problem is that the 16 volt 1.4A power adapter
is not working. I cracked open the box and could not find any obvious
faults. In circuit, the 68uF 400V filter cap charges to the peak line
voltage but that's about all that is happening. I cannot measure any
oscillation at the MOSFET. I removed the MOSFET from the circuit and did the
quick DMM check where you put some voltage on the gate and drain and then
check the resistance between the drain and source. That test passed. The D-S
resistance went down to two ohms.

I removed the switching transformer and took these measurements:
Primary winding that goes to the MOSFET: 0.3 ohms DC.
Then I used my ESR meter on the primary windings and it measured 32 ohms.
There is another primary winding (at least it's on the same side of the
transformer as the winding that goes to the MOSFET and I think it feeds back
to the controller) that measures:
0.4 ohms DC
The ESR meter measures open circuit.
I used my Bob Parker LOPT tester and it actually lit up all the lights when
applied to these windings.

The secondary measure 0.4 ohms DC and 7.3 ohms with an ESR meter.

I was wondering if anyone can figure out if these measurements mean anything
or is there a better method to test this.

Thanks for your replies.
--
David Farber
Los Osos, CA