[truant]

I've owned my Norh ACA2b almost a year and recently have lost a channel each on two of the inputs. I'm on my last one. I would be interested in taking care of this myself but have never opened up a stereo component and have heard that tube components can be especially hazardous to work on. Some pointers would be appreciated. Thanks...

[JohnR]

Well, the fault will likely be in the wiring between the inputs and the selector switch. Or possibly the selector switch itself. I'm slightly dubious about giving advice if you've not even opened it up to take a look, what would you say to doing that and posting a photo, and then we can go from there?

[truant]

Thanks JohnR. I'll get a picture up ASAP.

[TG]

I ... have heard that tube components can be especially hazardous to work on. Some pointers would be appreciated. Thanks...

The only thing you need to be more careful with in valve gear as compared to solid state is the high voltage lines.  Voltage on the power rails in most solid state is 35-75V, but in a valve preamp you may have 150-400V going to the plates.  This is, however, nothing to be concerned about as long as the preamp is unplugged at the time you work on it.  You only need to be especially cautious when testing a live circuit.

Two safety hints for valves:

1) Discharge the power supply capacitors.
http://www.repairfaq.org/sam/captest.htm see the section on "Safe Discharging of Capacitors"

2) Keep your left hand in your pocket when poking around in a live circuit.

Here is some more useful safety reading:
http://www.repairfaq.org/sam/safety.htm

Cheers
TG