Paul -
Have you tried another tube?
Have you re-tightened the socket and PC board mounting screws?
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-B, C-Line&
TR-4/C Service Supplement CDs
<www.k4oah.com>
[email protected] wrote:
Has anyone run into a problem with intermittent tube socket
contacts on an R-4(*)? I have an R-4A that apparently makes
intermittent contact on a pin or pins of V4. When first turned on the
receiver works fine but after it runs for a while an S-9 signal will
suddenly drop to S5 for a moment or two, then jump back up. Diddling
with the pins from underneath using an insulated wand will make the
signal come and go but I see nothing loose and no sign of a cold
solder joint (not that appearances always show them).
I used Deoxit on the pins and even used a round toothpick with the
tip soaked in Deoxit to "spin" by hand in each pin to remove
residue. I tried a couple of different tubes and even cleaned the
tube pins with Deoxit but it's still flaky. I tried making the pin
sockets a little tighter by gently pressing the sides in but the
problem persists. I also loosened and re-tightened the screws that
hold the socket down to ensure decent grounding. (NOTE: The chassis
of this R-4A is quite shiny, in fact remarkable condition, so I'd be
surprised if corrosion is a problem).
My next approach will be to re-heat all of the pins to eliminate
any cold joints and also to reheat the connections on the PCB that
feeds those pins.
Any other suggestions welcomed - and yes, I do need to measure
voltages (B+, etc.) on the tube when the signal drops and will do so
tonight.
73/arf,
Paul, K4MSG
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