Chuck -
The S-Meter being pegged full scale indicates that V5 may not be drawing
it's intended current. I'd start with a close mechanical inspection and
ohmmeter check of R69, and possibly R43, and push on them gently with a
probe. These resistors can often break in half, under overload, and not
show until a little pressure is applied.
IF one of them IS cracked, there may have been an internal short in the
tube in V5, or a breakdown inside T10. If not, then V2 or V4 stages are
drawing excessive current and will require further investigation.
There is very little DC on the stage before the AF GAIN control, (the
dual diode Product Detector.)
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Chuck Pool wrote:
Hi to all:
A couple of days ago there was a very loud crack, pop or bang then
some continuous crackling that came from the speaker. I was in the
next room when this happened.
At present, the receiver will not receive. The S-meter is pegged to
the right. When turning the radio on the S-meter smashes against the
right side of meter. Normal characteristics of the S meter, in the
past during warm up, has been a slow rise to the right and a gentle
lowering to the the left. The S meter would then settle to S-zero if
a dummy load was connected. The crystal calibrator cannot be heard now.
When moving volume control there is lots of crackling or scratching
noises.
I replaced all tubes in the radio and the above symptoms are
still present. I did not see any smoke or fire. During visual
inspection on top and bottom of chassis I did not see any burnt
components.
What should I do next?
73,
Chuck - AA5WG
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