TB-9-2920-225-34-1
100 AMP REGULATOR
TECHNICAL BULLETIN; CHECKOUT AND REPAIR PROCEDURES
NOVEMBER 1981
TB-9-2920-225-34-1 - Page 5 of 70
TB
9-2920-225-34-1
Figure 1–1.
100 AMP regulator.
1-4. Removal and Installation.
The regulator
1-5. Major Items Affected.
Because of the nu-
must be removed from the vehicle for testing and
merous vehicles affected, a listing of the vehicles
repair. The procedures given in this bulletin are
will not be supplied. Check the regulator’s NSN
for bench testing and repair only. Refer to the ap-
(2920-00-900-7993) or part number (10947439)
propriate vehicle manual for removal and instal-
in section IV of your vehicle’s repair parts manual
lation procedures for your particular vehicle.
for applicability.
Section II. FUNDAMENTALS OF SOLID STATE COMPONENT CHECKOUT AND REPAIR
1-6. Introduction.
a.
Checkout and repair of solid
state voltage regulators involves techniques dif-
ferent from those employed with mechanical volt-
age regulators.
b.
Before attempting checkout and repair of
solid state voltage regulators, follow the instruc-
tions of paragraphs 1–7 and 1–8,
1-7. Meters.
a.
The type of meter used to check-
out solid state components is critical and should
be limited to quality meters such as the TS-352 or
the Simpson 260 multimeters, or their equivalent.
When using an ohmmeter with unknown technical
specifications or characteristics, the following
checks can be made to determine if the ohmmeter
scales will cause damage to low power transistors.
(1) Check the voltage across the ohmmeter
leads as the ranges are switched. No scale should
be used if the voltge exceeds 3 volts.
(2) If the instrument is a combination volt-
ohmmeter, the positive voltmeter lead may not
be the positive ohmmeter lead. The polarity of the
ohmmeter leads must be known. Polarity can be
determined by connecting the ohmmeter to a
voltmeter. If the voltmeter moves up scale the
ohmmeter has the same polarity as the voltmeter.
1-2
If the voltmeter attempts to move down scale the
ohmmeter leads have opposite polarity, e.g., TS–
352 multimeter. If necessary mark the ohmmeter
leads positive and negative for reference.
b.
The ohmmeter readings obtained when check-
ing semiconductor devices depends on the internal
makeup of the meter, scale used, type of transistor
and its temperature. Therefore, exact resistance
readings are seldom given. Readings are usually
referred to as low resistance, which is less than
20
ohms; and high resistance which is more than 200
ohms. Occasional failures may occur which can
be detected by these tests. If readings obtained are
doubtful or operation of the regulator is not
proper, replace the transistors.
1-8. DOs AND DON’Ts For Circuit Repair.
a.
DO—When replacing solid state circuit
boards, clip the connecting wires, leaving a small
portion of wire with insulation to act as a refer-
ence for connecting points on the replacement
board.
b.
DON’T—Attempt to interchange circuit
boards between regulator models.
c.
DO—Use high quality resin core solder of
60–40 tin lead composition.
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