Chapter 10 537
Synthesizer Section
Unlocked Offset Lock Loop (Sampling Oscillator)
21.Check the end of L417 (nearest C445) with an oscilloscope. With the
oscilloscope input ac-coupled, a triangle waveform approximately 20
mVp-p should be present.
22.Short C441 with a wire jumper. (Connect the jumper from the end of
R462 nearest C441 to the end of R460 nearest C443.) This changes
the loop integrator into a voltage follower. Refer to function block AB
of A15 RF schematic.
23.Check the voltages at the following points:
24.If the voltages are not correct, suspect A15U408.
25.Remove the jumpers.
A15U408 pin 6 +2.5 Vdc (approximately)
A15X201 pin 1 +2.5 Vdc (approximately)
To Next Page
Loading...
