[R-390] Should this work?

[Barry]

Working on the "new" R390A.  I have it mostly back together (at least enough
to run some tests).  I tested everything except the RF deck by substituting
the modules into my working radio and everything I tested checked out
functional.

When I powered up the radio, I got nothing on the audio except a small hum
when the volume is turned up to 100%.  I didn't figure on hearing anything
in the way or radio signals since the RF deck is in complete need of an
alignment, but I did expect to hear some noise.

I injected the audio signal generator into pin 7 of the plug that connects
the IF deck (P112) and was able to get good audio on both line and local.

I then decided to take the IF output from the working radio's RF deck (with
the radio tuned to a good strong station) and plug it into the input of the
IF deck on the radio under test.  Since I had checked the IF deck by
substituting it into the working radio and it does work there, I figured I
should get some signals that way.  Still nothing.

Is this a valid thing to try?  I realize the IF deck still needs a touchup
for alignment, but it should be close enough to hear something through the
chain.  It worked when I substituted it into the working radio a few weeks
ago so I assume it should still be working.  Unless something has broken
since then (and I'll try substituting it again to make sure), I would think
this should produce some signals.  No?

Thanks,

Barry - N4BUQ