One or more resistors in divider
Check resistors, replace if
network (R6 through R18)
Partial failure of bridge rectifier
Check output of bridge
(CR1 through CR4)
rectifier(par 6-11b). If
a. Transistor Checks. Use the data below to check the operational parameters of transistors Q1 and Q2 (out of
Q1 or Q2
a. Collector-to-Emitter Sustaining
5 made; Ib =
Voltage (V,,) (sus)
b. Collector-to-Emitter Saturation
250 made; Ib =
Voltage (V,,) (sus)
c. Base-to-Emitter Saturation
100 made; Vce
b. Circuit Voltage Measurement. Voltage measurements at several critical points in the circuit for the V/H panel
Point of measurement
Junction of R20 and C1 and ground
Junction of R6 and emitter of Q1
and ground (-)
c. Resistance Measurements.
(4) Tag and unsolder the leads to the circuit
breaker (9). Remove the nut (10) and the washer (11)
resistance measurement is the out-of-circuit resistance
securing the circuit breaker to the plate (17). Remove
the circuit breaker.
measurements are: 88 ohms maximum across terminals
(5) Tag and unsolder the leads to the light
1 and 2 and 60 ohms maximum across terminals 3 and
assembly (12). Remove the nut (13) and the washer
(14) securing the light assembly to the plate (17).
Remove the light assembly.
(6) Tag and unsolder the leads to the switch
To set the V/H calibrate control R4, place a voltmeter
(15). Remove the nut (16) securing the switch to the
(dc) between the junction of R6 and the emitter of Q1
plate (17) and remove the switch.
and ground. Adjust potentiometer R4 for a reading of
(7) Tag and unsolder the leads to the
100.6 +0.5 vdc.
613. Disassembly and Reassembly (fig. 6-3, 6-4, 6-5,
connector (3) and the terminal (32). Remove nut (33),
washer (31), terminal (32) and connector (30) from the
(8) Remove the screws (18) securing the
plate (17) to the chassis (34). Remove the plate and the
(1) Loosen the two captive screws (2)
securing the cover (1) to chassis (34).
(9) Tag and unsolder the leads to the filter
(2) Pull out the component board assembly
(20). Remove the four screws (21) securing the filter to
(4). Remove components as required (fig. 6-3 and 6-
the chassis (34). Remove the filter.
4). To remove heat sinks from transistors, refer to
(10) Remove the screws (23), and the nut
figure -6 for attaching parts.
plate (24), connector (22) and grommet (25) from the
(3) Remove the setscrew (6) and the knob
chassis (34). Remove the contacts from the connector
(5). Unscrew the light assembly (12). Remove the four
with extracting tool MS24256-R20.
screws (8) securing the faceplate (7) to the chassis.
Remove the faceplate.
Change 1 6-7