Measuring the voltage changes when spin the VFO dial, steps?
J01(P06)
From pin C164, C165 ...
1khz, 2khz, 4khz, 8khz, 10khz, 40khz, 60khz, 80khz, 100khz.
Same lsb and usb on 3.7Mhz.
No hz changes, only khz in frequency.
tiistai 26. tammikuuta 2021 Mat Breton <
i.m.n8tw@...> kirjoitti:
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!!!
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-Mat Breton, N8TW
