John wrote:

How do you check a bridge rectifier in circuit to be absolutely sure it
needs replacing. Conditions: No power applied as 2amp fuse in the
transformer primary blows immediately power is applied. Usual short circuit
procedures followed throughout but I don't place too much reliance on this
test . BTW, the rectifier (B40 C3200/2200)) is in a theatre organ purchased
from an outfit no longer in business and space on the pcb is at a premium
and discourages using single diodes.
Thanks - John


the primary side of the xformer could be shorted.

to check the rectifier.
put your DMM on ohms, place the red lead on the
+ output of the rectifier and black on the -.
if you have a very low ohm reading, you have
either a rectifier or a capacitor or something
else connected to the supply shorted.
normally, a fuse won't blow instantly unless
it's shorted on the primary side.
have you checked for any shorted MOV's ?

the only way to know this, is to disconnect one
side of the secondary and put in another fuse,
then fire it up.
if you don't want to use fuses, use a lamp of
a set wattage that is near the fuse rating inplace
of the fuse. if the circuit is still shorted badly,
the light will glow and produce low current in your
circuit..


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