13
lead to the upper brush holder, black lead to lower holder,
and note the reading. Now reverse the connections.
*This test is not as conclusive as the Diode Test method
however, provided the first reading is a very high
resistance and the second reading far lower, then the test
is valid. Actual values will depend on the voltage
supplied by the particular meter for its resistance ranges.
The rectifiers are located in the small box on the back of
the Pacific body. To inspect them remove the four screws
and the plate. This has been sealed with polyurethane
sealant.
After removing the screws insert a thin blade to cut the
seal. The sealant must be renewed on re-assembly after the
mating faces have been cleaned.
Failure to do this can cause severe brush gear
corrosion in future.
Unsolder the commoning links between the rectifier
outputs and check outputs separately. If a new rectifier has
to be fitted, unhook the spring connections to the brush
holders in the lower body section noting polarity,
(Brown wire = positive output = upper brush holder)
and unsolder the four stator wires from the rectifiers.
ELECTRICAL SECTION
Note.
By far the most common cause of reduced output is
corroded wiring between Pacific and battery.
Before suspecting the machine, check any screw terminal
or crimp connections and all cable runs between Pacific
and battery.
Possible faults to consider if reduced output is suspected:-
a) Poor wiring connections.
Inspect all the screw
terminals in the Pacific circuit for signs of fatigue or
corrosion.
b)
Sticking brushes
or associated brushgear contact
problems. See Pivot Section.
c) Faulty Rectifiers.
The rectifiers and metal oxide
varistor should last the life of the machine.
The most likely cause for their demise is accidental
reverse polarity connection of Pacific to battery.
If this is suspected the rectifier diode bridges must be
checked. Reverse polarity connection can also melt the
solder on the brush holder spring connections, these can
be checked by removing the pivot and looking into the
lower body section.
A simple method of checking the machine's output is to
disconnect it from the battery and short together its output
leads whilst turning the shaft by hand. A marked increase
in resistance to turning should be felt as the shorting
occurs.
Diode Test.
This test will show if the rectifier diodes are
either open or short circuit.
If your multimeter has a diode check feature, select this (if
not select the highest resistance range) and having
removed the brush caps and brushes, apply the red meter
excess side play, if this is suspect replace the lower
bearing and "O" ring. Failure to do so may wear the pivot.
If the rectifier cover is removed,
it must be totally
resealed
before returning the Pacific to service.
Multimeter Setting
Lead Position
Diode Test
Red to
upper holder
No Reading
or Many
Megohms*
OK
Reading
or Low
resistance
US
Black to
upper holder
12V
(2 diode
or Markedly
less*
OK
No Reading
or High
Resistance
US
Ohms x 100 Range
Figure 10. Pacific 100 Internal Wiring
Summary of Contents for Pacific 100
Page 10: ...10 Fig 8 ...
