Signal Checks - HP 5065A Operating And Service Manual

Model 5065A
Circuit Diagrams, Theory, and Maintenance
Table 5-3. Circuit Checks (Continued)
CIRCUIT CHECK
Switch Position
5 MHz
CONTROL
ERROR
2ND HARMONIC
1 MHz and 100 kHz
Normal Indication
38 to 42
with no load at
front or rear
5 MHz jack
-50 to +50
Zero
20 to 40
38 to 42
with no load con­
nected to front
and rear jacks
Nature of Meter Indication
Meter signal comes from A13
Buffer Amplifier through A17(10)
to S4(L). Signal represents 5 MHz
output; is less when loaded.
Meter signal comes from A9 Inte­
grator Amplifier through A17(11) to
S4(M) and also to rear panel CON­
TROL jack. This signal represents
the frequency correction voltage
that steers the A10 Quartz Oscil­
lator. When this meter signal ex­
ceeds about +2.5 V or -5.0 V,
INTEGRATOR LIMIT light will come
on. When this occurs; setOSC
FREQ ADJ COARSE control for
zero indication on meter.
Meter signal comes from A8 Phase
Detector (filtered from the A12
photo diode output and amplified
in A7 (AC Amplifier). This signal is
thefundamenntal 137 Hz ac error
signal that is zero when "on
frequency".
Meter signal comes from A14 Logic
Assembly through A17(13) to S4(P).
This signal represents 274 Hz volt­
age level from A7 AC Amplifier.
These signals represent the amount
of 1 MHz and 100 kHz at front and
rear output jacks. 1 MHz signal
routes from A6 Freq. Div. through
A17(14)toS4(R). 100kHzsignal
routes from A4 Freq. Div. through
A17(15)toS4(S).
Checks to Make if Reading Abnormal
If signal is low, but not zero: (1)
Check front and rear jacks for
loading (meter reading is estab­
lished with no cables or other loads
connected).
(2) Perform "Output Voltage and
Waveforms" check described in
Figure 8-20.
If signal is zero: Check 5 MHz
signal path from A10(1V) to A3J2,
from A3J3 to A13J1, and from A13J2
and J4 to front and rear 5 MHz
jacks. Check 5 MHz meter circuit
in A13 Buffer Amplifier.
Should be reset to zero with OSC
FREQ ADJ COARSE (cw to make
meter go-). If meter does not re­
spond, set FUNCTION switch to
LOOP OPEN. Meter should zero;
1) if it does, perform signal check
in Table 5-4, 2) if meter does not
zero, check FUNCTION switch
circuit, meter circuit, and A9
Integrator Assembly (see foldout,
Page 8-33).
If reading is not normal, switch
CIRCUIT CHECK switch to CON­
TROL and make "Control" checks
above.
If meter reading has slowly dropped
to less than 20, refer to instructions
in Paragraph C of PERIODIC
MAINTENANCE, Section 5-7. If
meter reading has suddenly dropped,
indicating a possible trouble in RVFR
or RF sections of servo loop, see
Table 5-4, SIGNAL CHECKS.
Check front and rear jacks for loads.
Push START-AUTO START switch
momentarily to START and then
release. Signal should come up to
proper value. If not, check A4
or A6 circuit as required.
5-9