Musical Fidelity B1 MKII

After 14 years I finally got one.
After set it up on my living room, the problems started:
- Sound distortion
- No heat

Small adjustments on the right pots of each channel:
- No distortion of sound
- Normal temperature
- A "thump" sound when the volume is off

Bigger adjustment on 4 the pots:
No distortion.
Overwhelming temperature on the Toroidal
The first 2n are hot the next 4 are burning and the final 2 are cold.
After 2min the amplifier shuts down and the fuse is blown.

Saturday I went to 3 electronic houses to see if anyone could help me with this problem and all of them said NO, of course with various reasons to that.

Should I change all of the 8 2n's?



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It sounds like you have some transistors failed and they are causing a heavy load on the supply. It looks like someone already did replace them - MF usually rebrand the transistors. You may be better using some more rugged transistors like MJ15024/5 or MJ21193/4.

Chances are the driver transistors also failed. These amps are not really well designed to be honest - those heatsinks are far too small.

First of all thanks for your help.

I bought it having in mind a nice overhauling, like changing all the capacitors and resistors by audio-grade ones. Also I will change the opamp.
But it should have arrived in working condition. Now it´s a problem that I don´t have the proper knowledge to deal it.
I´ve already ordered most of the caps, and I'm looking for the so called Rugged transistors.