HP 5065A Operating And Service Manual page 306

Model 5065A
Circuit Diagrams, Theory, and Maintenance
LOGIC ASSEMBLY A14 THEORY
Logic Assembly A14 monitors various circuits and con­
trols front panel CONTINUOUS OPERATION and
INTEGRATOR LIMIT lights. These two front-panel
lights give a constant indication of instrument oper­
ation. A14 Functional Diagram is a diagram of theA14
Logic Circuits.
The separate logic functions fed to A14 are listed,
together with the normal and abnormal conditions
which control the CONTINUOUS OPERATION and
INTEGRATOR LIMIT lights, in the table of A14 logic
inputs.
With a normal "on frequency" condition, CR13 input is
" H " with CR13 conducting, Q18 conducting, and the
CONTINUOUS OPERATION light on. At this time, all
stages connecting to CR13 input are nonconducting.
When Q4, Q14, or Q7 conducts in response to a "no go"
logic input, CR13 input goes "L" and stops conducting,
Q18 turns off and the CONTINUOUS OPERATION light
goes out.
Q14 is noninverting so that a " H " input in normal oper­
ation corresponds to a " H " at Q14 output which con­
nects to CR13. Correspondingly, Q15 input is "L" for
normal operation. Summarizing, the conducting tran­
sistors for a normal "on frequency" condition are: Q5,
Q9, Q6, Q8, Q10, Q12, Q3, and Q18; CR13 also con­
ducts. Nonconducting transistors for a normal "on fre­
quency" condition are: Q16, Q4, Q15, Q14, Q2, and
Q7.
The cell oven and lamp oven inputs are the voltages at
the inputs to the cell and lamp oven heaters. Since these
heaters are connected to the dc supply voltage (+22 to
30 volts) these inputs go "L" with an increase in heater
current and "H
1
with no heater current.
With a cell oven "no heater" condition, the cell oven
input is near zero volts and Q5 is turned off inpressing
an " H " signal on Q15 and the CONTINUOUS OPER­
ATION light is turned off.
The lamp oven input works in a similar manner as the
preceeding for a "no-heater" condition with Q10 and
Q12; and for an "over-heat" condition with Q9.
The 2nd Harmonic input to Q3 is a positive dc voltage
when "on frequency" resulting in a normal "L" input to
Q15. When the system is not operating correctly and
2nd harmonic drops out, Q3 input is "L" and a resulting
" H " at Q15 input turns off the CONTINUOUS OPER­
ATION lamp.
The Synthesizer lock signal input is only present when
there is no phase lock in the Synthesizer Assembly and
consequently the synthesizer output is "off" frequency.
The Synthesizer "no go" input is " H " which causes Q16
to conduct, delivering a "L" input to Q14 and the CON­
TINUOUS OPERATION light is turned off.
The light disable function that comes from the FUNC­
TION switch is developed when the FUNCTION switch
is placed in OPER connecting +20 volts to C2. The re­
sult is a short-duration positive pulse at Q4 input. Q4
A14 Functional Diagram
LIGHT r
DISABLE ., I
FROM -2-f
FUNCTION '
SWITCH
5
LAMP 3
OVEN
^ + 2 0 V
I
r
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i
8-60