HP 8112A, Operating, Programming And Servicing Manual

Page: 219 / 406

-0 . ? V
- 1 . 6 V
�
7 0 n s
�
Figure 1 0.3-9. Period Generator ramp signal pin 20
3. Check the trigger output signal at pin 21 of U200 against
Figure 10.3-10.
4. Check the signal being sent to the delay generator IC220 at TPl
against Figure 10.3-10.
�1�----
l ms
�--�•1
OUTPUT � Pl� l 0
�
OUTPUT TO DELAY 50% 50%
GENERATOR ON TP I
-ZV
l ms
---•I
Figure 1 0.3-1 O. Period Generator output signals
5. Check the period generator operation against Table 10.3- 10 and
Table 10.3- 1 1 :
Table 1 0.3-1 0. Period Generator Operation
U200 Pin Mnemonic Description State
5
PERC Period control voltage input L
2 ERP Period error output signal L
10 PIC
Period input store select
See Table 10.3- 1
1 1
to 18 LD7 - LDO Data to be latched into See Table
10.3-2
the input store of U200
R212 PVC Period vernier current See Table
1 0.3- 1 1
6. Verify that voltage at U200 pins 1, 4 and 5 are at virtual ground
(
min. -40 m V max. 0 V
)
Servicing the Timing and 1 0.3-17
Slope Generators