TM 9-4910-730-14&P
TROUBLESHOOTING
c. When disconnecting wiring, always tag wires to
5-1. GENERAL
facilitate reassembly.
5-2. Failures and malfunctions may often be traced
to relatively simple causes. Before troubleshooting a
malfunctioning tester, check for available electric
p o w e r supply, loose broken or frayed wires or
tester. The numbers on the schematic refer to the
broken or slipping drive belt.
figure and index number in the Parts List (Section 7)
for the appropriate component.
5-7. TROUBLE ANALYSIS CHECK CHART
5-4. When troubleshooting this or any electrical
equipment, observe the following precautions;
the distributor tester. The chart contains the most
a. Always use a meter range higher than the larg-
common troubles that may be encountered, prob-
est expected voltage when making voltage readings.
able cause of the trouble, and action that may be
b. Connect meter leads with the tester turned off.
taken to correct the condition. Refer to the parts list
Turn on tester to read meter, then turn tester off to
for parts replacement.
disconnect meter leads.
Corrective Action
Probable Cause
Trouble
Electrical power switched off or disconnected.
Connect or switch on power.
Tester will not start
Replace
Drive belt broken.
Defective switch.
Replace
Replace
Worn or defective drive belt.
Output rpm low
Defective tachometer.
Check Tachometer accuracy.
Repair distributor and retest.
Speed adjust does not
Overload due to defective distributor being
vary speed
tested with frozen or tight bearings.
Replace
Damaged speed adjust mechanism.
Replace
Defective meter.
Tachometer does not function
Replace
Defective sensor.
Defective vacuum gauge.
Replace
Vacuum system does not work
Replace
Defective regulator.
Replace
Defective vacuum pump.
Defective test lead or clip.
Replace
Dwell meter does not work
Defective meter.
Replace
Defective circuit board.
Replace
Select STD DIST or PULSE GEN as
Selector switch in the wrong position for
Stroboscope does not work
required.
the type of distributor being tested.
Repair or connect as required.
Defective or unconnected test lead.
Replace
Defective strobe lamp.
