Tecumseh ECV100 - 120 Technician's Handbook page 58

CHECKING THE SYSTEM: To check the system,
disconnect the plug and measure the D.C. voltage at the
red wire terminal (diag. 24). Measure the A.C. voltage at
the yellow wire terminal. With the engine running, the
minimum values should be:
3 Amp D.C.
2500 R.P.M. - 8.0 Volts D.C.
3000 R.P.M. - 11.0 Volts D.C.
3600 R.P.M. - 13.0 Volts D.C.
5 Amp A.C.
2500 R.P.M. - 8.0 Volts A.C.
3000 R.P.M. - 11.0 Volts A.C.
3600 R.P.M. - 13.0 Volts A.C.
If the above minimum values are noted, system is okay.
Check for defective lights, wiring or switches. If less than
above values are noted, pull back the protective shrink tubing
from the diode. Using an A.C. voltmeter, check the voltage
going into the diode from alternator, at the lead on the
alternator side of the diode (diag.25).
All Models
With the engine running, the minimum values should read:
2500 R.P.M. - 20.0 Volts A.C.
3000 R.P.M. - 25.0 Volts A.C.
3300 R.P.M. - 26.5 Volts A.C.
3600 R.P.M. - 29.0 Volts A.C.
If low or no voltage is experienced, replace the alternator. If
the alternator puts out the minimum A.C. voltage, replace
the diode.
7 Amp Alternator System Regulator-Rectifier
External to Engine
CHECKING THE SYSTEM: To check the system,
disconnect the D.C. or B+ wire at the switch end and
measure D.C. voltage between the lead and ground (diag.
26).
With the engine running, minimum values should read:
2500 R.P.M. - 9.0 Volts D.C.
3000 R.P.M. - 11.0 Volts D.C.
3600 R.P.M. - 14.0 Volts D.C.
If the minimum readings are noted, system is okay. Check
for defective ammeter, wiring, etc. If less than the above
readings, disconnect the plug from the regulator-rectifier,
and insert the A.C. voltmeter probes in the two outside
terminals (diag. 27).
With the engine running, minimum values should read:
2500 R.P.M. - 12.0 Volts A.C.
3000 R.P.M. - 14.0 Volts A.C.
3600 R.P.M. - 18.0 Volts A.C.
If the minimum readings are noted, the alternator is okay;
the regulator-rectifier is defective. If less than the above
readings, the alternator is defective. See Chapter 9 for
"Disassembly Procedure".
54
A.C.
B + TERMINAL WIRE
RED
YELLOW
25
D.C. VOLTMETER
REGULATOR/RECTIFIER
MUST BE GROUNDED
26
A.C.
27