MarelliMotori MEC-20 Manuel Utilisateur page 37

Possible failure causes:
- Mechanical damage due to impact/shock.
- Improper AVR resin application process.
Actions:
- Replace the AVR.
#2 - VISUAL / MULTI-METER CHECKS
CHECK D –Box/Terminals
(Plastic support/Terminals)
Visual inspection:
- The AVR must not show any sign of mechanical damage, or any broken component; in addition, terminals
must not be covered with resin.
Multi-meter check:
- None.
Check result:
- If the result of all the above checks has been positive, tick the ok box in section #2 of the report form,
Check D.
- Otherwise leave the box blank.
In case of component failure:
Possible effects on regulation:
- If the plastic support is broken, the AVR cannot be reliably and safely installed inside the terminal box.
- If terminals are covered with resin or damaged, it might be impossible to establish a proper connection
with the alternator. This may result in various AVR operating faults, depending on the terminals concerned.
Possible failure causes:
- Mechanical damage due to impact/shock.
- Improper AVR resin application process.
Actions:
- Replace the AVR.
#2 - VISUAL / MULTI-METER CHECKS
CHECK E – Free-wheeling diode
(Free wheeling diode)
Visual inspection:
- Check that the diode shown in the figure is not
damaged.
Possible damage types are:
1- Diode blown.
2- Diode broken.
Multi-meter check:
1- In the multi-meter, select the diode measurement
mode.
2- Connect the multi-meter probes to terminals - and
+ of the AVR.
Expected values are:
COM probe on +: 0.5 to 0.7V.
COM probe on -: open (OL).
If at least one of the above measurement is not met, the
free- wheeling diode is damaged.
963857154_U
Free-wheeling
diode
37