I have a Studiomaster P7. The channels will cut out from time to time. Sometimes if I push the fader all the way up the signal will start flowing again, other times I need to play around with the cable and connection.
I'm wondering if this sounds like a fixable problem?
One thought I had was it could be a matter of cleaning the connections by taking the top off the board.
I may be wrong, but this seem to be a problem either with the cable or with the connector.
Basically, when you push the fader up, you increase the potential difference (at a level of several mV) between 2 points of circuit having a bad connection and it's enough to establish a temporary channel having lower impedance through the faulty connection.
So this doesn't seem like a fader issue, especially if you obtain this 'reconnection' using different faders.
If you know which connector has this problem, try to replace the cable connected to it (P7 is a large mixer, but I suppose it's one of the Main / Bus / Auxiliary outputs having a TRS or XLR connector type).
If same behaviour is encountered, it means that the problem is either in the mixer, either in the other end of the cable (amplifier?). To determine that, try to switch to another amplifier for a test, or connect the same amplifier to another mixer and see if same thing happens.
In either case, most such 'sound interruption' problems, the issue is at the external connector, and it's not hard to replace with a bit of soldering skills and the replacement connector. There are rare cases when the issue is more towards the inner workings of the equipment, and a specialized technician / engineer is required to fix these. In fact, if you haven't done such operations before, your professional mixer is not the best equipment to start tinkering with