Adjustment Of Vfo Circuit - Fujitsu M2361A Customer Engineering Manual

6.7.4 Adjustment of VFO circuit
The following describes how to adjust and test the VFO (Modulator and
Demodulator) circuit (PCB 550204U) in case none of variable resistors have been
adjusted. Refer to Table 6.7.5 and Figure 6.7.17 for monitor point and
location.
Table 6.7.5 Variable Resistors in VFO Circuit
Item
I
RV No'1 Test point
I
Specification
t---V-C-O-F-r-e-e---r-u-n-n-~ng
----- -: -- RV5
------~~_oI·~-~f~~tO·
(0-
Frequency
I
Reference
p~~~: W~~t;
r
·~~3-
t
,
~-------------
...-----_._--
Phase Adjustment RV4
(1) VCO Free-running Frequency (RV5)
W7
WB
WI0
Refer to (2)
Refer to (3)
Connect CN2-24 (Connector 2, Pin 24) to ground, and adjust RV5 so that the
pulse period or frequency of WIO matches Figure 6.7.20.
Disconnect the cable between CN2-24 and ground after adjust or confirm the
the item.
WlO
-t . - . - --50% _\'-----150%
Tl
T
J
=
SO.9ns±O.Sns
(f]
=
liT]
=
19.6608MH1.d'fr)
Figure 6.7.20 VCO Free-running Frequency Adjustment
(2) Reference Pulse width (RV3)
\---
Read or write any data, and adjust RV3 so that the pulse width of W7
matches Figure 6.7.21.
W7
Eel Vl
T
2
=
lSns±O.Sns
Figure 6.7.21 Reference Pulse width Adjustment
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