Mecc Alte ECO-ECP Série Manuel D'instruction Et De Maintenance page 22

d) Replacement of diode bridge
The diode bridge varies according to the model of the generator. It
can have three separate sectors with two diodes fixed on each
sector (T30), or one circular body (T18) with 6 diodes. The first
type (T30) is used in the alternator models 34-38, whereas the se-
cond one (T18) is used in the 40,43 and 46 versions.
Diodes can be easily inspected with a multimeter: simply discon-
nect the wire of the particular diode and check its resistance on
both directions. A perfectly functioning diode will show a very high
resistance in one direction and a very low resistance in the oppo-
site direction. A faulty diode will show either a very low resistance,
or an infinite resistance in both directions. Once the whole sector,
or the whole bridge, is replaced, remember to tighten the screws
with a suitable tightening wrench and to strictly comply with the
polarities and the diagrams indicated by Mecc Alte.
Generator versions 28-31-32.
Procedure to check the diodes of the exciter rotor.
Necessary equipment :
12V battery
12V-21W lamp (or alternatively 6.8Ω-30W Resistance)
Voltmeter (for instance, multimeter on scale VOLT d.c.)
Warning: before performing the following actions, it is
necessaty to disconnect the 2 cables connecting the main
rotor to the diode bridge (+and-).
TEST OF THE DIODES ON THE "NEGATIVE"
Connect the equipment, as it is pointed out in the picture A
(table 26 page 45)
Fix the cable connected to the lamp to the negative terminal of
the bridge, as it is pointed out in the picture A (table 26 page
45)
Connect the terminal "Probe" to the point A1 (it is checked the
diode 1), then to the point A2 (it is checked the diode 2) and
finally to the point A3 (it is checked the diode 3); check the
readings on the voltmeter in relation with what is reported on
the table (table 26 page 45).
TEST OF THE DIODES ON THE "POSITIVE"
Connect the equipment, as it is pointed out in the picture B
(table 26 page 45)
Fix the cable connected to the negative terminal of the battery
to the positive terminal of the bridge, as it is pointed out in the
picture B (table 26 page 45)
Connect the terminal "Probe" to the point A4 (it is checked the
diode 4), then to the point A5 (it is checked the diode 5) and
finally to the point A6 (it is checked the diode 6); check the
readings on the voltmeter in relation with what is reported on
the table (table 26 page 45).
ECO - ECP MANUAL
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MAINTENANCE
IMPORTANTE
ECO-ECP iMANUAL December 2013 Rev. 03
ENGLISH