[frsimen]

Your measured voltages on the phase detector board all seem to be reasonable now.

The measurements on the logic board are encouraging. Pin 17 will only have a very brief spike when you operate the switch, so I wouldn't be too worried about that for now. Pin 13 should change from high to low or low to high as the direction of the spin wheel is changed. If you only turned the spin wheel one way, or only pressed the up or down button, the voltage at pin 13 wouldn't change.

I would go back to the phase detector board and check for waveforms at the various test points on that. For clarity, you will need to be careful to say TP for a test point or a plain number for one of the termination points, otherwise things will get very confusing. A rough measurement of the frequency (or period) of any pulses would be helpful too.

If you can use the following settings it will make it easier for your results to be checked against a working unit:

Tuning speed: Fast
Range: 128-256MHz
Steps: 25kHz

Your 50MHz oscilloscope won't be able to display anything useful from the input to the dividers, as the 128MHz to 256MHz is well outside its bandwidth. Further down the chain you should see trains of pulses.

There is also a useful looking 37.5kHz reference signal on pin 18 that should be checked.

These checks should help to identify if the signal from the VCO is being divided down and fed to the phase detector.

I wrote the above before seeing Peter's reply. Do his checks first, they are likely to get you to a successful outcome quicker than my method!

Paula