Musical Fidelity Amplifier Repairs
Musical Fidelity A1
They were designed by Tim de Paravicini and create a huge amount of heat even though they are only rated at 20 Watts per channel.
The above pictures are from a Swedish Mk I with a 2 piece top heat-sink. It is in very good condition internally considering it reaches 50-60°C!
The Mk II (below) has perforated side plates. If I used one regularly then I would remove the side plates to provide ventilation through the internals of the amplifier when powered up. This one also had a one piece top\heat-sink. The switches needed cleaning and a capacitor needed replacing, thankfully Musical Fidelity decided to use 105°C caps in this and later versions so it hadn't dried them all out. An output transistor was faulty in one of the amps, they are 2N3055\2955 complementary pairs.
This was working but one channel didn't sound quite right. A modification had been added to the volume - an add on board had been fitted, more of later, anyway when I powered it up, one channel didn't work at all. One of the phono inputs had pushed through with the phono plug and needed gluing back in place. The sound was then found to be intermittent in one channel. The wires had come loose from input to the Vero board (just to the left of the tape switch). I thought the switch was faulty, then I found a couple of breaks in the copper strips on the board, worked okay after all this, but noted the input impedance was around 10k which might be too low for some sources.