HP 9810 A transformer

[BartDB]

On http://www.hpmuseum.net you can find the service manual and Tony Duell's repair guide.

From the schematic in the sevice manual, it seems that pins 1 to 7 are all taps of the secondary coil - so with a simple multimeter they will all look shorted (primary are probably black wires going straight into the transformer).

The best test for the transformer is to disconnect all the secondary connections and apply power - if the fuse blows again it is likely the transformer is at fault.

However, it would be good to first check the rectifier bridge and capacitors after the transformer as this could also be a likely cause.