Could not find any issues with the VCF voltages, tried going in the VCF input and also checking the output of U1440, looks like good variable voltages.
I wanted to see if the triangle buffer, sine wave shaper, and square wave generator worked. What I did was put paper under all the contacts of the time base switch so I could go into Q1725 clean. I used an externally generated triangle waveform. I found that the triangle buffer was OK.
What happened when triangle function button was pressed was the triangle made it to the front output BNC. When switched to sine, the output was also a triangle wave, but
barely noticeable was a small curve to the wave. Since the sine wave shaper is a goesinto-goesoutta circuit, I think that also has an issue, but we'll put that aside for now because it's not causing the main problem.
What came out when the square wave function was selected was ... nothing. I found that there was no signal at the output of U1700A into the flip flop. I found that the reference at pin 5 of U1700A was not correct, so that no output of the comparator was possible. In the circuit description it states that at the input of U1400C p12 should be ~400mV (it was), and this is simply buffered out. But what was at the output was -19 mV.
I isolated the output p14 by removing R1711 and pulling J1611, but the output did not improve. Since I had R1711 pulled I connected a ~400mV adjustable voltage to p5 of U1700A and lo and behold the output started producing highs and lows in accordance with the triangle wave input and the output responded to the voltage being adjusted. If this part of the circuit does not work no square waves are generated and no loop back goes to Q1531/Q1433.
So as of this afternoon I believe a problem lies in the U1400 chip - a CA324 quad op amp. I also believe that the sine-shaper has a serious issue - perhaps the CA3045 NPN transistor arrays.
Any comments are welcome.
And now it's Miller Time.