MarelliMotori MEC-20 Manuel Utilisateur page 36

In case of component failure:
Possible effects on regulation:
- The alternator output voltage is lower than the rated voltage and equal to the residual one.
You cannot set the proper value using the VOLT trimmer.
Possible failure causes:
- Mechanical damage due to impact/shock.
- Presence of resin on the fuse terminals and/or on the fuse holder blades.
- Not enough contact between the fuse and the fuse-holder.
- Improper connection.
- Exciter failure: check the insulation of the exciter with a megaohmmeter (insulation is appropriate if
resistance is >30MΩ).
- Short circuit between terminals + and -.
Actions:
- Replace the fuse and try restarting the alternator.
In case of any further fuse failure, replace the AVR.
#2 - VISUAL / MULTI-METER CHECKS
CHECK C –Trimmers/Dips
(Trimmer/Dip switches)
Dip-switches
Visual inspection:
- The AVR trimmers and dip-switches must show no sign of mechanical damage; in addition, they 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 C.
Otherwise leave the box blank.
In case of component failure:
Possible effects on regulation:
- If the trimmer is covered with resin or damaged, the trimmer rotor can no longer be operated for any
setting.
- If the dip-switch is covered with resin or damaged, it might be impossible to have the proper stability set-
up for voltage adjustment.
963857154_U
Trimmers
36