HP 5065A Operating And Service Manual page 242

Model 5065A
Circuit Diagrams, Theory, and Maintenance
A5 MAINTENANCE
Troubleshooting Table
NORMAL OPERATION
Digital divider circuits provide one pulse-per-second
output ticks available at front and rear panel 1 PPS BNC
output jacks. The divider drive is an internally con­
nected 1 MHz signal from Frequency Divider Assembly
A6. Option 001 circuits also provide drive for front
panel digital clock.
OPERATIONAL CHECK
Complete operational check is given in Table 5-2,
item 7.
TROUBLESHOOTING
The entire digital divider assembly may be removed and
reconnected for troubleshooting. Extender board (HP
Part No. 05061-6073) furnished, makes circuit board
—components available for testing.
Digital divider power supply common is isolated from
instrument common. To observe waveforms and meas­
u r e divider voltages, divider common may be connected
to instrument common for troubleshooting with no ad­
verse effect. However, this connection must be removed
_when divider is reassembled.
Each circuit board inputs and outputs are available on
interconnection board assembly A5A5. Thus, trouble
_may be isolated to one specific board assembly before
disassembling the entire unit. Troubleshooting table
and schematic diagrams provide troubleshooting
information.
Periodic adjustments to divider circuits are not neces­
sary. When adjustable components or components re­
lated to adjustable components are replaced, the fol­
l o w i n g adjustments should be made.
a. A5A2T1 Adjustment. With instrument in
normal operation (frequency divider on) connect RMS
Voltmeter to A5A2T1 secondary. Adjust A5A2T1 for
maximum voltage indication on voltmeter.
— b. A5A2C9 Adjustment. With instrument in
normal operation (frequency divider on) connect oscil-
'oscope to A5A2Q6 collector. Adjust A5A2C9 for most
symmetrical square wave observed on oscilloscope.
c. A5A2C10 Adjustment. With instrument in
lormal operation (frequency dividers on) set TIME DE-
.AY thumbwheel switch to "000000" and 0-1 jisec TIME
"DELAY adjust to max. cw. Externally synchronize
digital divider circuits (Paragraph 3-23). Using an oscil-
oscope, compare external synchronization pulse with 1
__'PS output pulse. Adjust A5A2C10 for 10jisec 1 PPS de­
lay + 1 Msec.
Will not synchronize
to external pulse.
Incorrect output pulse
shape.
TIME DELAY switch
does not affect output
pulse time delay.
Check external pulse
characteristics (Table
1-3). Check sync cir
cuitry A5A2 (Q3, IC1,
Q5, andQ7).
Check output circuits
(A16) A5A4(IC1,Q1),
(Q7andQ10),and
13.3 V supply (A16).
Check each switch posi­
tion (Table 5-2, Item 7).
If symptom is in only 1
or 2 switch positions,
check preset circuitry
associated with those
positions including pre­
set coupling diodes and
the associated decade.
If symptoms are present
regardless of thumb­
wheel settings, refer to
Table 5-6.
If output stops only
when thumbwheel
setting is "999999"
trouble is probably in
A5A3(IC13,IC12B, or
IC2D).
MODULE REPLACEMENT
No adjustments required when Digital Divider Assembly
or circuit board assemblies are replaced.
O TO I SEC I
" — D E L A Y H
I PPS PULSES -=TL
T\.
MASTER
CLOCK
DELAY
PRESET
INFORMATION
PRESET
CLOCK
VARIABLE
DELAY
IPPS
DELAYED
"TICK"
PULSES
0 TO I /iSEC
U - D E L A Y - ^
I I
8-31