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Table 2-3. Voltage Checks (Power On)­Model 03
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TB-9-2920-225-34-1 100 AMP Regulator (Solid State) Manual
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Figure 2-10. Vap-Air model 26440001-04.
TB 9-2920-225-34-1
If the regulator still does not function correctly
Table 2-4. Substitutes for D1-Model 03
it will be necessary, if local skills permit, to test
each component. All the parts should be checked
with an ohmmeter and the capacitors checked with
a capacitance meter. The circuit board traces
should be checked with an ohmmeter to make sure
that there are no cracked traces. Traces with hair-
line cracks will show good at lower temperatures
and will tend to show open circuit at higher tem-
peratures. If the board seems good at room tem-
perature, but the regulator still fails, this could
be the cause.
Section IV. VAP-AIR MODEL 26440001-04
2-8. General. Figure 2-10 is a plan view of the
if cracked, broken or missing. Coat washers with
insulation compound per MIL­S­8660, NSN 6850­
regulator with the cover off. Figure 2-11 is an
end view of the regulator showing the receptacles
00-880-7616.
and the voltage adjustment points. Figure 2­12 is
c. Diode.
an exploded view of the diode mounting. Figure
(1) Remove four screws holding transistor
2­13 is a relay location. Figure 2­14 is a view of
and circiut board mounting plate, and move plate
the circuit board and transistor heat sink. Figure
to one side.
2­15 is a view of the circuit board showing the
(2) Place negative ohmmeter probe to the
electrical test points. There are 12 electrical test
topside of diode D4 (see fig. 2-12).
points. Figure 2­16 is an electrical schematic dia-
(3) Place positive probe to the bottom of D4.
gram of the regulator. Table 2­5 lists the resist-
Meter should indicate low resistance.
ance checks, and table 2-6 1ists the voltage checks.
(4) Reverse probes. Meter should indicate
Table 2­7 is a transistor substitution list.
2-9. Checkout and Repair.
(5) If other readings are obtained replace
a. Voltage Adjustment Rheostat (Rz) (Power
diode D4 (MR1122), NSN 5961­00­103­1519 (see
Disconnected).
(1) Place ohmmeter test probes to terminals
d. Relay.
of the rheostat (see fig. 2-10).
(1) Place ohmmeter probes across relay coil
(2) Rotate rheostat fully clockwise, reading
terminals (see fig. 2-13).
should be approximately 250 ohms.
(2) Place ohmmeter probes across terminals
(3) Rotate rheostat fully counterclockwise,
(see fig. 2-13). Meter should read infinity (open
reading should be less than 5 ohms.
circuit).
(4) If other readings are obtained, replace
(3) If other readings are obtained, replace
rheostat.
relay, NSN2920­00­735­9542.
b. Transistors.
(4) Reinstall transistor and circuit board
(1) Remove transistors Q4 and Q5 (see fig.
mounting plate.
e. Detailed Circuit Checks.
(2) Position transistors as shown in figure
(1) Table 2­5 contains "power off'' resistance
2-1, and check them separately (see fig. 2­2).
checks of the circuit (see fig. 2­15 for test points).
(3) If resistance values cliffer from the values
(2) Table 2-6 contains "power on" voltage
shown in figure 2­2, replace the transistors
checks of the circuit (see fig. 2­15 for test points).
through cannibalization or requisition transistor
f. Functional Check. Check the performance of
Q4, Vap-Air part number 26316033-12 (2N3441),
the regulator on the test stand and make final volt-
NSN 5961­00­054­4141, or transistor Q5, Vap-
age adjustments. Voltage output should read 28
Air P N 26316033­70 (2N3773), NSN 5961­00­
volts. If the regulator does not function properly,
929­5014 (see table 2­7 for substitutes).
perform the following:
(4) Check the mica insulating washers be-
( 1 ) Check wires and connections.
tween the transistors and mounting plate. Replace
2-13

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