hi mike k6nhv.
thanks for all the help in jan. for the problem with this amp. several comments
were spot on. the soft start was the problem and i found it after chasing the
smoke to its source. after tearing down far enough to get to things i found the
10 ohm 25wt resistor was not being shorted out. three 470 ohm resistor in
parallel going to the coil of the soft start relay had failed. one read 580
ohms, the other two went open so the ry never engaged. i changed most of the
parts in that circuit and put it back together and all was well...for a while.
i had only used it a few times when i turned it on and heard or felt? (had my
head phone on and feet resting on the power supply) a thump. the amp was dead.
long story short, i started eliminating sections at a time until i was down to
the transformer coming on ok by its self. as soon as i plugged the h.v.
secondary plug back into the rectifier board fuse #2 blew again.thats the one
on the primary winding that has the soft start and also goes to the higher
voltage of the two secondary winding's. i did not find a problem checking with
dvm on R-200 scale, but when i went to the 2k scale i found a reading of 1,090
ohms from the primary to the secondary on those two.windings
poking around i found mention of another person with same thing-fuse only blew
when the secondary was plugged in just to the rect. board with nothing else
connected. strange problem the article said.
so now not sure where to go. im an old fart on ssi and i got quite a bit
invested in this old girl already so can't just toss it and go buy another, but
can't spend a fortune on it either. any suggestions will be greatly
appreciated. don't know if this transformer is still available but understand
when it last was it was very costly. perhaps someone is making a replacement or
maybe there is another available that will work in this application?
thanks again for the help and to those who make this forum available. 73 mike
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