how to decide fuse size?

I've built i 2ch 312 and don't really know how to decide fuse size. I have tried to measure current on the powercord splitting one conductor, turning all the relay's on, but can't get an deacent reading...anyone?

kjell

pri mains i ass sume, not B+ sec fuse for backup?

this is scary your first time, but no biggy with low power.
disconnect the xfmr sec leads that go to the rectifier bridge.
short out the transformer leads, thats right, connect them with a wire nut, plug it in, measure pri ac current, s/b around 100 ma or so, depending on how many 312's you have chained.

just make the fuse so that when the xfmr is shorted. the fuse blows
so ie 100 ma draw, make fuse 50 ma slow blow.

guess what happens if you make the fuse 120 ma so it wont ever pop?

thats right, varnish in the morning, varnish in the evening, aint we got fun!
cj

CJ,

When shorting out the transformer, if I have a 2X24 tranny, do I connect all four leads together??

mike

yes, and try and get it done in about ten seconds

(your leads should be set up beforehand)

stand back and plug it in.