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Model 5065A
Circuit Diagrams, Theory, and Maintenance
g.
Connect oscilloscope vertical channel through a
50-ohm feedthru to A10P4. Oscilloscope display should
be 5 MHz, .2 V peak-to-peak. Remove oscilloscope and
reconnect A10P4.
h. Set CIRCUIT CHECK switch to 2ND HAR
MONIC. Adjust OSC FREQUENCY X10-
10
control maxi
mum
clockwise,
maximum
counterclockwise,
and
return to 250. CIRCUIT CHECK meter should track with
control movement.
i.
Disconnect cable from -EFC on oscillator as
sembly. Connect dc power supply common lead (-) to
-EFC on oscillator assembly. Connect positive lead (+)
to chassis ground. Slowly adjust dc power supply to -5
volts. CIRCUIT CHECK meter should track with power
supply. Disconnect power supply and reconnect -EFC
cable.
j .
Set CIRCUIT CHECK switch to OSC OVEN, 5
MHz, SUPPLY, and observe CIRCUIT CHECK meter
indication at each position.
Meter indications should
agree with Table 3-1. This completes the oscillator
circuit checks.
OUTPUT VOLTAGE AND WAVEFORMS. In addition to
the circuit checks, the following checks can be per
formed, using equipment listed in Table 5-5. To observe
5 MHz output voltage and waveforms:
a. Terminate rear panel 5 MHz output jack with
50-ohm termination and connect an RMS voltmeter to
front panel 5 MHz output jack. Output level should be
at least 1 V rms. If it is not, use adapter cable provided
with instrument and connect ac voltmeter with 50
load
to A10J3 ("1 V"). Signal should be
1 V rms.
If this
signal level is ok, troubleshoot 5 MHz signal path from
A10 oscillator assembly to front (or rear) panel.
If
signal level is less than 1 V rms at A10J3, realign output
crystal filter as described below.
b.
Remove 5 0 f i load and, using the adapter cable
connect ac voltmeter to A10J4 ("DIV").
Voltage here
should be greater than 60 mV.
If output from A10J3
("1 V") as measured above is
1 V rms and output from
A10J4 ("DIV") is less than 60 mV rms A10 assembly is
probably defective and should be replaced.
Realignment of Output Crystal Filter.
a. Remove ac and dc power from instrument.
b.
On bottom deck unsolder 115 Vac connection to
A10 assembly. See adjacent Figure for location of these
terminals.
c. Tape the ends of these wires so they cannot
short or make contact with the chassis.
d.
Remove the 4 screws which secure the A10
assembly to the instrument chassis.
e.
Check to see that the wires removed in step 2
are properly insulated.
f.
Reconnect
ac
power,
allow
instrument
to
warm up.
g.
Connect ac voltmeter with 50£2 load to A10J3.
8-52
h.
Lift A10 assembly up so that holes on front are
accessible. Then, using a non-conductive screwdriver.
adjust "5 MHz filter ADJ" (see adjacent Figure) for maxi
mum on meter. This should be 1V rms or greater. If it is not
replace A10 Assembly with restored unit 00105-6034.
i.
Remove ac and dc power and reconnect 110 V
leads to bottom terminals. Replace protective cover or
110 V terminals, replace 4 hold-down screws, and cable
on J3.
~
.*TM5?*'
C7 OSCILLATOR FREO
COARSE ADJ
CIO 5MHZ FILTER ADJ
-TO A3 MULTIPLIER
_ . . _
TO A6 FREO
' ' ' * \ _
\ v y g r
DIVIDER
ijv* V - * T r ^ W ^ T " a-* Mil
DC CONTROL
, „
VOLTAGE
fe
ll 7AC SUPPLY
TO OVEN FAST
HEATER
T
T
T
T
1
f
1
NOTE
If Standby Battery Option 002 is installed,
—
remove instrument top cover.
Remove ac
power and fuse F4 located on instrument
deck.
MODULE REPLACEMENT
~
To remove Oscillator Assembly A10, proceed as follow
a.
Remove ALL operating power.
b.
Remove bottom cover and disconnect all elf -
trical connections.
c.
Remove 4 screws holding oven assembly in
place.
d.
Remove oscillator assembly from instrument.
e.
Replace
oscillator
by
reversing
the
above
procedure.
f.
After replacing the new oscillator assemL,',
perform turn-on and operational check.
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