HP 8562E, Service Manual

Page: 412 / 482

For YTO main coil spans, the YTO is locked at the beginning of the sweep and the sweep
ramp is summed into the main coil tune driver.
1. Perform the YTO adjustment procedure in Chapter 2, “Adjustment Procedures.” If the
YTO adjustments cannot be performed, continue with step 2.
2. Set the spectrum analyzer to the following settings:
Start frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stop frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9
3. Verify that a -1.2 V to -4.8 V ramp (approximately) is present at pin 2.
4. If this ramp is not present, troubleshoot the main/FM sweep switch. See function block H
of Al4 frequency control schematic.
5. Measure the output of the main coil tune DAC at pin 3. At the frequency settings
of step 2, this should be -2.48 V. If the voltage is not -2.48 V, troubleshoot the main coil
tune DAC. See function block E of Al4 frequency control schematic.
In YTO FM coil spans, the YTO loop is locked and then opened while the sweep ramp is
summed into the FM coil. The FM coil sensitivity is corrected by changing the sensitivity of
the FM coil driver.
1. Perform the YTO Adjustment procedure in Chapter 2, “Adjustment Procedures.” If the
YTO adjustments cannot be performed, continue with this procedure.
2. Set the spectrum analyzer to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sweep time
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ms
3. Check for the presence of a 0 V to -10 V sweep ramp at pin 14 (input to the
main/FM sweep switch). Refer to function block H of Al4 frequency control schematic.
4. Check for the presence of a 0 V to V sweep ramp at pin 6 (YTO FM coil
driver). Refer to function block M of Al4 frequency control schematic.
5. Check the state of the Main/FM sweep switches as indicated in Table 11-15.
6. The rest of the procedure troubleshoots the YTO FM coil driver.
Refer to function block M of Al4 frequency control schematic.
Table Settings of Sweep Switches
Switch Switch State
Closed
Open
Closed
Open
Switch Control Line
1
8
9
16
Control Line State
High
Low
Low
High
1 Synthesizer Section