[R-390] AGC problems

[Larry H]

 Glad your dusting off your 390As and getting them to work.

On the one that won't go to -7 vdc, did it adjust ok before you recapped
it?  If so, perhaps a cathode accidentally got grounded.  You should not
need to load the gen.

On the one that is dead on the 3 lower bandwidths, the 2 kh filter is used
on all 3, maybe there's a problem in that area.  You might want to check
C553 again to make sure it is not leaky.

As for correct agc operation - did you check C551 for leaking to ground?
If nothing is connected to either terminal, then that's not it.  Also, make
sure the antenna trimmer cap shaft insulator is still good.  The cap shaft
is at agc potential.  The usual agc problem is incorrect load (too much) on
the agc line.  With the agc link removed on tb102, term 3 should read 500k,
but you need to disconnect R545 to get a useful reading, about 3 meg.  Try
some other measurements with the units cables disconnected.  The rf deck
should be about 1.8 meg.

No need to use a matching network for this work, but should when making s/n
measurements.

Regards, Larry