16 Sep
2008
16 Sep
'08
11:44 a.m.
I asusme
you've foudn the mains smoothing capacitors (normally a few
hundred uF at 200V each). _Carefully_ (you are dealing with live mains!)
measure the voltage across those with the machine on. Expect about 350V
across the 2 in series.
I get about 320V. The sceond
cause is an open-circuit startup resistor. Start from the +ve
side of that mains smouthing capacitor pair and look for a high value
resistor (a few hundred k) from there to a point in the chopper circuit.
These resistors have a habit of failing open. Desolder it and test.
There's a pair of 100K resistors on the other side of the smoothing
capacitors and they check out OK.