Equipment For Troubleshooting; Safety; Parts Replacement - Hobart 90 C 20 Operation And Maintenance Manual

OM-2031
NOTE: Reference symbols (S9, etc.), used in the Trouble Shooting Chart, are identified on Schematic
and Connection Diagrams.

3. Equipment for Troubleshooting

A good quality multi-scale volt ohmmeter is the only instrument required for trouble shooting. At least two
"jumper" leads with "alligator" clips and test prods will be required. The 12-V, engine electrical system may
be used as a 12-V DC power source. If a test box, part number 388318-2, is available, tests may be made
more quickly and accurately, however, the test receptacle connector (31, Fig. 1) may be used by inserting
the test points of a volt ohmmeter into proper terminals of the connector. Refer to Fig. 8.

4. Safety

WARNING: EXERCISE EXTREME CARE TO AVOID CONTACT WITH HIGH
VOLTAGE LEADS AND COMPONENTS WHICH COULD CAUSE SERIOUS
SHOCK AND INJURY IF TOUCHED WHEN TROUBLE SHOOTING OR OPER-
ATING THE EQUIPMENT.

5. Parts Replacement

To lessen end item "down" time and to get a faulty machine back "on-the-line" as quickly as possible, the
"black-box" concept of parts replacement is reflected in the trouble shooting chart. For example, if a com-
ponent in the protective relay tray is defective, the quickest way to remedy the situation is to replace the
complete tray assembly and send the old tray to stock.
Assemblies which lend themselves to this concept are:
Generator control tray
Over-undervoltage module
Protective relay tray
Over-underfrequency module
Voltage regulator
Overload module
Protective monitor module
Electric governor control "box"
Governor actuator
The above items are in addition to normally replaced items such as fuel pump, injectors, relays,
etc.
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August 5/89 Revised