Merc-O-Tronics 98 - FIELD DISCHARGE DIODE CHECK; Field Discharge Diode Testing Procedure

8.
9.
If
the
reading
is
battery
voltage,
both
the
transistor
and regurator
resistor
are
burned
open.
The
transistor
and
resistor,
if
damaged,
must
be replaced
before
proceeding
with
the
remaining
checks.
10'
To
replace
the
resistor,
merery
unsolder
the
connections.
11.
To
replace
the
transistor,
disconnect
battery
and
all
regulator
leads
and
remove
regurator
from
junction
box.
Then
remove
the
two
transistor
attaching
screws
and
unsolder
the
two
transistor
con-
nections
inside
the
regulator
box.
NorE:
Do
not
reconnect
the
regulator
leads
until
after the
field
discharge
diode
and
suppression
diode
have
been
checked-
PI.ACE
APER
BTTWETN
CONTACTS
OHMMITER
OHMMTTER
CHECKING
FIEI.D
DISCHARGE
DIODT
FIETD
DISCHARGE
DTODE
The
following
tests
can
be made
on
the
Merc-o-Tonic
ana\yzer
selector
switch
position
No.
3
Meter
Sca-le
No.
3.
1.
To
check the
field
discharge
diode, plaee
a
small
piece
of
clean
white
paper
between the
voltage
contacts
to
insulate
them.
see
Fig.
3g.
2-
connect
small
leads
from
analyzer
to
the
,,F,
and
..BAT,'
(Fig.
3g)
terminals. (Note
the
readings).
3.
Reverse
the
lead
connections
to
the
,,F,'
and
!.BAT,'
(Fis.
3g)
ter_
minals.
(Note
the
readings).
4.
If
either
reading
is
very
high (infinite),
the
regulator
field
discharge
diode
is
open.
5.
If
both
readings
are
approximate|y
zero,
the
regulator
fielddis-
charge
diode
is
shorted.
6.
Remove
the
small
piece
of
paper.
7.
To
replace
the
diode,
merery
unsorder
the
connections.
CAUTION:
Excessive
heat
will damase
diode.
REGUTATOR
RTGUTATOR
ee