After installing a used GNS-430 in my RV-7 project, I'm noticing that the
volume knob doesn't seem to be working -- The output is only at one
level, and can only be altered by the headset's own volume control. I
doubt it'll be loud enough for flight, even with the headset turned up
all the way. I've tried it through the intercom (Sigtronics), and also
without.

The Audio Hi output is connected to the intercom (or directly to headset
jack, during my trouble-shooting), and the Audio Lo is grounded at the
firewall.

Any thoughts?

Brooks Wolfe
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