Farm Fans C-2120A, Руководство оператора, Страница: 52 / 68

problem is due to some other cause. Check for a break
in the power train (broken chain, drive key, clevis pin,
coupler, etc.).
NOTE: In freezing weather, the meter rolls may be
loaded with frozen grain. Operate lower burner for sev-
eral minutes to thaw grain, then reattempt to operate
meter rolls.
TO LOCATE THE JAM
To determine which meter roll is jammed, whether
drive-side or driven-side, feel the tension in the top and
bottom sections of the meter roll crossover chain (see
Fig. 6-11). If tension is equal in both sections, the drive-
side meter roll is likeliest to be jammed. If lower section
of crossover chain is extremely tight and the tension
will not equalize when attempting to deflect the bottom
section, the jam is likely to be in the driven-side meter
roll.
TO CLEAR JAM FROM METER ROLL
Make certain power is OFF and locked out. Loosen the
chain tightener and remove the crossover chain.
CAUTION: Keep hands away from sprocket
teeth to avoid injury from chain backlash as a
result of any torsional buildup in the system
(as caused by the jam).
With crossover chain removed, place a pipe wrench on
the sprocket hub of the jammed meter roll and attempt
to turn the meter roll. Rotate backward and then for-
ward several times in an attempt to dislodge the object
and clear it through the roll. If this is not successful,
have an assistant turn meter roll and at tempt to locate
jam by sound. Once location is determined, first seal
off grain flow by inserting the Grain Column Cut-Off
Damper service tool from inside the plenum as
described in Fig. 6-16. Then from outside the dryer,
open the meter roll access door to remove any foreign
object.
SCR MOTOR CONTROL
When installing a new SCR motor control, check torque
switch setting, control voltage jumper position, and
armature voltage jumper position. Set as shown in Fig.
7-10.
ADJUSTING SCR MOTOR SPEED
1. Max Pot Adjustment
With dryer unload circuit energized, set the SCR Speed
Control knob on the ASC panel to 100%. Using a small-
blade screwdriver, adjust the Max pot to obtain 155
VDC across the DC motor armature terminals A1 and
A2 on the Woods SCR motor control board. When this
adjustment is completed, the Unload Rate meter on the
ASC panel should indicate 100%.
2. Min Pot Adjustment
Set the SCR Speed Control knob on the ASC panel at
the 10% setting. Adjust the Min pot to obtain 15.5 VDC
across the DC motor armature terminals A1 and A2.
When this adjustment is completed, the Unload Rate
meter on the ASC panel should indicate 10%.
3. Recheck Max pot setting (step 1) and readjust if nec-
essary. Repeat step 2 and readjust Min pot if neces-
sary. Rechecking the Max and Min pot settings one
time should be sufficient.
50
CONTROL
VOLTAGE
JUMPER - SET
TO 0-10 VDC
F1 FUSE - 15 AMP
250V ABC 15
SET MIN &
MAX POTS
(SEE TEXT)
IR POT - PRESET
AT FACTORY
ARMATURE
VOLTAGE
JUMPER
POSITION
(180V)
SUPPLY VOLTAGE
CONNECTION (230V)
TORQUE SWITCH
SETTING
(3/4 HP MOTOR)
WOODS.DSF
SCR MOTOR CONTROL 415-2302-8
ON
OFF
A B C D
L1 L2 F1 F2 A1 A2
Fig. 7-10 Woods SCR motor control board and
settings