GSI Outdoors PNEG-630 - Manual (Page 57)

Portable Dryer Troubleshooting
56
• If 220 volts AC is present across input of
the SCR drive board (L1 and L2) then
check for voltage across the output of the
board. Change your voltmeter to check for
DC voltage at a range above the 200 volt
scale. Put the leads across A+ and A-. The
voltage across these two points will vary
depending on where the speed control poten-
tiometer is turned. Also try turning the poten-
tiometer up and down. The voltage should go
from zero to approximately 180 Volts DC. If
zero voltage is present across the A+ and A-
terminal, first try to disconnect the wires from
these two points and then check for DC volts
again. If the voltage returns, suspect a bad
motor or a problem in the wiring to the motor.
If the voltage does not return, suspect a bad
DC drive board.
• The DC drive system on the portable
dryer is used to control the output of grain
from the dryer. It is adjusted from the
front of the control box using the high and
low metering roll potentiometers. Compo-
nents used in this circuit are the SCR
contactor, SCR drive board, DC motor/
gear box, and the input/output board from
the Electronic Monitoring Control System.
• All voltage for the drive system comes
from terminals 1-(L1) and 3-(L2) of the
SCR contactor. There should be 220 volts
AC across these two points even if the
unload system is turned off. If this voltage
is zero, check your incoming main power.
• When the unload system is turned on you
should be able to observe the SCR
contactor energizing. The power to the
contactor should turn on and off with the
unload switch. You can check for power by
putting an AC voltmeter across terminals
A1 and A2. Across these points you
should read 120 Volts AC. Also on the top
of the contactor you can see a plunger pulling
in whenever the contactor coil gets power. When
the contactor is energized, power is transferred
from terminals L1 and L2 to terminals T1 and
T2. Understand that L1 and L2 are the Input
of the SCR contactor and T1 and T2 are the
Output of the contactor.
• The wires attached to A+ and A- go directly to
the DC drive motor on the dryer. You may
remove the top cover of the motor and check
for the same DC voltages mentioned above at
the motor. If the voltage is not present try to
disconnect the wires, then check for DC volts
again. If you do not get any voltage then look
for a broken or loose wire between the motor
and the drive board terminals.
• If the voltage is present suspect the motor
or the gear box. Removing the motor from
the gear box and trying to run the motor only
is one way of narrowing down the problem, or
you may want to remove the chain and see if
the metering rolls are froze up. Using a pipe
wrench is an easy way to try and rotate the
metering rolls.
Symptoms: Metering Roll will not turn,
dryer shutdown-"Metering Roll Drive Failure"
DC Drive Metering Roll System
• Next if all the above checks out okay, put
your voltmeter across terminal L1and L2 of the
SCR drive board. You should get 220 Volts AC
across these points when the Unload Switch Is
Troubleshooting Tips
in the 2 Speed position. If this is present
then the SCR contactor and input/output board
are okay.
Metering Roll Operation
Check the SCR Drive Board
Check the Motor