On Sat, 29 Jul 2017 17:27:21 +0100, T i m wrote:

D1,4 test as short cct.

I would take those out and check outside the circuit.

If the short is at the output of the bridge rectifier, and all four
diodes are good, you should measure a diode drop (0.6 V or so) across
the diodes in both directions.
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RoRo