"Sala Massimo" wrote in message m...
Hi

I am the happy owner of one A1 amplifier, bought in 1991.
It is 20 Watt class A amplifier, build around MOSFET.

In the last months the A1 started to malfunction, the volume knob works very
bad: when I turn the knob I hear strange noise ("shhh shhh" as there is sand
inside the knob, and also some "crack") and the volume output isn't in
accordance with the knob position.

I took the unit to repair, but they said me they cannot because they haven't
the potentiometer.

I ask you:
1) is really the pot the culprit ?


2) where can I found one (or two) spare parts?
It is a Alps 0071 50KAX2 (I cannot measure the value because it is
soldered).


3) by the way, do you know which are the exact final transistors?
I found on newsgroups many codes:
original: A1 N8915 and A1 P8919
poor quality? 2N3442 and 2N5876
good ? Motorola MJ15003 & MJ15004

My unit (model A1 X) has these transistors:
A1N9020 A1N9034
A1P9022 A1P9018
I don't understand why are there four different codes instead of two exact
couples!


4) which are Musical Fidelity address, Emai and phone?

ciao, Massimo
Italy

Hi you will find that the codes on the output transistors are usually week numbers, the types are A1N and A1P which are NPN and PNP devices the number after that is the year/week number e.g. week 20 of 1990 or week 34 of 1990. The devices we have in stock here at work have similar codes on, you may find that Musical Fidelity can supply a replacement Alps Pot for your unit but I seem to remember you have to run a bunch of wires from the tags to the pcb.

Musical Fidelity
15/16 Olympic Trading Estate
Fulton Road
Wembley
HA9 0TF
Tel UK 0208 900 2866

Cheers
Alec