On Thursday, August 13, 2015 at 5:51:55 AM UTC+1, Phil Allison wrote:
Gareth Magennis wrote:



The customer said it had been in storage the past 2 years. He fired it up
today and it blew all the main fuses in his gaff.
So sounds like it may have been short like yours and Phil's, then blew open.


** Hmmm - that should not happen.

However, if the amp worked even for a few seconds, the chunky relay next to the PTC closes and bridges it out. If the primary shorted out after that, it is possible the relay contacts became instantly welded closed.

The fault current could then trip the breaker in the 30A ring mains and easily blow any fuse fitted inside power plug.

A subsequent attempt to switch on the amp would result another huge surge and maybe make a track on the PSU board vaporise.

BTW:

IIRC, the secondary voltages and currents are printed on the side of the tranny. The tranny is about 800VA and it ought to be possible to have one made that is close to the same size and ratings for an acceptable cost.


... Phil



They are. 74/0/74 and 18.3/0/18.3


Cheers,


Gareth.