Table of Contents
Advertisement
4-28 PROTECTION CIRCUIT
4-29 This circuit prevents the high voltage doubler
from exceeding approximately 4kV which might oc-
cur if the feedback loop were to malfunction.
Diodes CR37 and CR38 are connected directly
across the control winding and rectify (monitor)
the voltage across this winding.
The rectified
voltage charges capacitor C24, and when
it
ex-
ceeds a predetermined level, neon tube VR3 fires.
The resulting positive going voltage turns on Ql 7
which in turn shorts the control winding of trans-
former Tl, thus, reducing the output of the high
voltage doubler.
Overvoltage control R71 deter-
mines the level at which VR3 will fire and, there-
fore, controls the maximum output voltage of the
high voltage doubler.
4-5
4-30 REFERENCE REGULATOR
4-31 This circuit supplies regulated de bias volt-
ages to the voltage input circuit and +15Vprogram-
ming voltage to the voltage control circuit.
Diodes
CR22 through CR25 and capacitor Cl6 rectify and
filter the 4 3 Vac developed across the secondary
of T2.
The 56 Vdc is regulated by transistor Ql2
which is controlled by Ql3 and VRl.
The +15V
programming voltage is developed by constant cur-
rent amplifier Ql4-Ql5 which is connected to the
-40V reference voltage.
Resistors RSI and R52 are
selected to provide precisely the correct program-
ming current.
Procedures for selecting these re-
sistors are included in the adjustment and calibra-
tion paragraphs in Section V, Maintenance.
Advertisement
Table of Contents
Troubleshooting
