Another bad start: a cautionary tale

I was listening to a Brewers broadcast on an old Sony CFS-1030 boombox (AC powered) when suddenly I heard a pop - and then it was dead.  No smoke was seen or odor noticed so not sure what happened.  I got the box apart and there is no evidence of any problem, so now it's time to start buzzing things out to see what may have opened up or shorted.  

I found the service manual here:

https://elektrotanya.com/sony_cfs-1030.pdf/download.html 

Here is the power portion of the schematic:

The Australian version seems to have fuses, this one just has jumpers.

I believe the problem was that I was using a small switchbox to turn the radio on and off (since it can't be turned "off off" because the power transformer is connected directly to the AC line).  Unfortunately this switch box has 3 positions: center off, full power and 1/2 power (half wave rectifier).  I was using the switch box with a foot heater which didn't care about AC versus pulsating DC.  However a transformer power supply does care.  I must have put the boombox on 1/2 power by accident.  The pop sound must have come from the transformer primary somewhere.  It "worked" OK for a while but eventually it must have overheated ?  It looks like a fairly standard transformer so maybe I can find a replacement ?  We'll see.

But I will just abandon the Sony boombox for now and pivot to the Sony CMT-EP313 mini stereo.  This is a nice little AM/FM radio/CD player/cassette player with an AUX input with a remote, too.  But one weird thing:  no mute !  The only way I could figure to mute the radio manually was to switch to the AUX input since it is unconnected.

The bottom line: don't feed pulsating DC to a transformer based supply.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm