Arfa Daily wrote:

A particular board that I'm currently involved in repairing, makes use of a
couple of 15nf 630v dc caps in the primary side of a smps transformer. They
go open or low value, and are easily found initially by running an ESR meter
over them. Good ones go about 38 ohms, bad ones over 80 ohms or beyond the
range of the meter. Once you've got them out, a value check will confirm
that they are faulty. The originals are those 'boxy' blue metalized film
ones with 15mm pitch on the leads. Some are fitted with the shiny brown
epoxy dipped metalized film types, which interestingly, don't seem to fail.

Blue tends to suggest polypropylene caps IME (good for pulses) which figures in
such an application although you don't state where they are in the circuit.

How about some more info on what they do ?

Graham