OK, I have an idea. But first a few basics:
1. The VFO frequency is driven by a microcontroller controlled PLL into the 1st mixer. The scheme is pretty complex and is shown on page 49 of the tech supplement.?
2. The Microcontroller controls this PLL via a 21-bit wide digital bus.
We don't know if the problem is in the PLL or the microcontroller (or the connectors/wiring between), so let's first divide the problem in two.
Using a multimeter, check the VFO board connectos P07 and P08. P07-Pin 1 is the LSB, and P08-Pin13 is the MSB. As you spin the VFO dial, you should see the lower level pins toggle back and forth in BCD-like fashion (pin 1 toggles every 10 hz, pin 2 toggles every 20hz, pin 3 toggles every 40 hz, and so on).
Give this a try and let us know if the uC signals are getting from the CPU board to the VFO board!!!
--
-Mat Breton, N8TW
Mat Breton N8TW