Jim -
Well, since you just replaced the RF GAIN pot, I would carefully check
all your work in that area since most of your problems ARE related to
the RF GAIN / AVC circuitry.
I would suspect C91 and/or D6 for starters, this is the bias supply
which drives the AVC et al.
The S-Meter should go to zero with no signal / PRESELECTOR detuned / no
antenna / RF GAIN full CW. There is a ZERO pot on the right side of the
cabinet to make this adjustment. Turning the RF GAIN control full CCW
"should" cause the S-Meter to go very near full scale, +/-. This is set
by the RED trimpot near the center under the chassis.
The neon PTO in use light on the R-4B should be on except when the T-4XB
is connected, turned on, and the TRANSCEIVE switch is in the XMTR
position, when the PTO in use light in the T-4XB should come ON and the
R-4B light should go OFF. IF the R-4B light is on all the time with
the T-4XB connected properly, likely suspect would be Q10.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
J G wrote:
Hi,
I have been trying to use my R4-B/T4X-B lately. A few problems have
decided to show up.
#1-- The R4-B receives on "Standby". This is a new problem this
afternoon. This morning, it behaved as it should.
#2-- The R-4B is suddenly noisey, 60 cycle noise. A capacitor, most
likely. This and problem #1 started at the same time. Are they related?
other problems, not new today:
#3-- The S meter does not go all the way to the right in standby. It
was like that before problems 1 & 2 came along. I do not recall if
this was an intermittent problem or not (i.e.: maybe at times it did
swing all the way to the right). The S meter seems to act normally in
receive compared to another receiver.
#4--The PTO indicator neon indicator does not work the same on this B
line as on my other B line. The R4-B neon stay on no matter if the
frequency control is separate, rcvr, or xmtr. On the other B line, the
R4-B neon is off if using xmtr frequency control for transceive. A
minor item for sure, but which is correct?
All these problems are the same with or with out the T4X-B turned on.
Within the past week or two I did clean the switches and pots with
Caigs and replace the RF gain pot (10K).
In the event I cannot repair these on my own, is there someone in the
Madison, WI, area that does such repairs?
Thanks,
Jim
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