30 May
2004
30 May
'04
5:16 a.m.
SMPS are always a pain to troubleshoot, and I've always opted to find a
replacement. In this case that isn't probably feasible so ---
I'd buckshot the components in the switch driver, such as the IC. Sounds
like the traansistor/FET isn't getting drive, or it is being biased hard
on. Do you have a bad rectifier on one of the outputs? Escessive load?
If all else fails, maybe you can find another PS that will fit into the
box, with the same voltage outputs/currrent ratings.
Gary Hildebrand
St. Joseph, MO
Hi,
Rescued an Apple clone from the trash yesterday (Ci Base48) - appears to
be
all there, but power supply is dead. I've had a bit of experience with
small
DC transformerless switchers, but not with mains power, transformer based
switchers like this.
<snip>
- Power transistor does not appear shorted - Removed
from circuit and
using
a diode test function, it shows two normal semiconductor junctions.
Can anyone offer suggestions on where to look next? Are there any common
failure
modes of this type of power supply design?
Regards,
Dave