Folks,
First of all, my Omni is a C model. I always thought that D was after
C, but it seems that the "D" was for digital, and C included the WARC
bands.
Following Mike's advice, I have studied the description on how the
counter works, and especially how the presets change the digits. I
habe also checked all diodes and transistors.
D5 and D6 plus Q3 enable the first digit for bands over 10 MHz, and it
was working OK.
The preset lines use two transistors and several diodes to "feed" the
preset inputs CA (for 1) and CD (for 8) in sync with the DD6 and DD5
display signals. In my case, the upper bands were short by 8 MHz,
which leads to a lack of CD signal.
When dismounting the board to check the bottom traces I have seen the
bottom pin was bent, so the connector was seated but with no contact
for CD. That was impossible to see from the top.
Lo and behold, once straightened right and connected, the counter is
working just fine.
The VFO, though, is gripped again, so I guess the easiest way to solve
the problem which does not require dismount the whole rig is to build
a external VFO with an Arduino, connect it through the back port, and
let the counter show the frequency...
Thanks for your help, Mike. It has been an educational experience.
jon, ea2sn / ae2sn
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