CCWN ! 76:82           
                               
PETIT LOGIC SYSTEMS
DIAGNOSTICS FOR THE PCF-1 COHERENT CW FILTER

1. TIME BASE PORTION: Trigger the scope from TP5. Place vertical
   inputs at TP3 and TP4, with 5volts/cm gain. Apply power and
   the 1 Mhz freq. std. signal.
   SCOPE GETS NO TRIGGER SIGNAL: CONTINUE BELOW
   SCOPE GETS TRIGGER: SKIP TO STEP 2
   Examine waveform at IC1 pin 1~ with a 10 Megohm probe and d.c.
   coupling It should be a l-MHz squarewave at least 2 volts
pk-pk
   and centered at ground potential.
   
   Examine IC1 pin 11: 100 kHz, unsymmetrical square wave.
   
   IC2 pin 11: 20 kHz
   IC6 pin 12 with S2 in 40 bits/sec position:   4 kHz
         20 bits/sec                             2 kHz
                  10                              1 Hz
                   5                            500 Hz
                   2                            200 Hz
                   1                            100 Hz
   
   Set S2 at 10 bits/sec. Examine IC6 pin 12: 100 Hz pulses.
   Examine IC5 pin 12: 10 Hz pulses.
   Set up according to the beginning of this step and verify
trigger
   signal to scope.
   
2. With S2 at 10 bits/sec, TP3 and TP4 should show positive
pulses
   spaced 100 milliseconds apart. The pulse from TP4 should lead
the
   pulse at TP3. As S1 is rotated both pulse chains should
advance
   or retard in 10 millisecond steps with respect to the trigger.
   Rotating S2 should increase or decrease the repetition rates
of
   the pulses; the rate at each setting must be equal to the
setting
   in bits/sec.
   If any of these tests fail, replace or repair circuitry or
components
   IC5. IC6. IC7. S1 and S2.