TROUBLESHOOTING
d. Do not connect test equipment (other than
multimeters and vacuum-tube voltmeters) out-
Tools and test equipment required for main-
p u t s directly to a transistor circuit; use a
tenance of Power Supply PP2309A/U are
coupling capacitor.
given in appendix II.
e. Make test equipment connections carefully
so that shorts will not be caused by exposed
test equipment connectors. Tape or sleeve
(spaghetti) test prods or clips as necessary to
Refer to TB SIG 357 for troubleshooting
leave as little of the tip exposed as needed to
techniques and precautions to be observed
when troubleshooting transistorized circuits.
make contact to the circuit under test.
Some general precautions to be observed are
f. Use only the multimeter authorized for use
given in a through f below.
on this equipment. If a substitute must be
a. Use a pencil-type soldering iron with a
made, do not use multimeters with a sensitivity
power rating of 50 watts or less and 40/60
of less than 20,000 ohms per volt, or ohmeter
circuit batteries in excess of 3 volts.
solder with a Iow-melting point when making
Soldering Connections to the transistors. Do
not use a soldering gun to replace parts in the
transistorized circuits:
When an abnormal symptom has been ob-
served in the equipment, look for a description
b. use a heat sink when removing or in-
of this symptom in the Symptom column of the
Stalling soldered transistors or diodes. Exces-
chart below and perform the corrective meas-
sive heat will damage a transistor or diode.
ures shown in the Corrective measures column.
c. If any of the test equipment does not have
If no operational symptoms are known, begin
an isolation transformer in its power supply,
with item 5 of the preventive maintenance
c o n n e c t one in the primary ac power input
checks and services chart (para 4-3) and pro-
circuit.
ceed until a trouble symptom appears.
