Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055 • 17
Checking Procedures
*Bridge Rectifiers
1.
Turn the power switch OFF and unplug the
machine.
2.
There are several type of rectifiers with different
types of terminal identification. Use the drawing below
that best represents the type oof rectifier you are
checking
3.
Remove all wires from the rectifier being checked.
4.
Set Ohmmeter to the diode check mode, if so
equipped. If your meter does not have this mode, use
the highest range ohm scale.
5.
Plug the red lead into the meter in the connection
marked ohms.
6.
Plug the black lead into the meter connection
marked common or ground.
7.
Place the black lead of your meter on the terminal
marked (+).
8.
Use the red lead of your meter to check to the
other two (2) AC terminals.
9.
The readings from these terminals should not rep-
resent a short (0.00). If at any time during this proce-
dure you obtain a reading that represents a short, the
rectifier must be replaced.
10.
Place the red lead of your meter on the terminal
marked (-).
11.
Use the black lead of your meter to check to the
other two (2) AC terminals.
*Optical Encoder (Code 44)
1.
Press and hold the SHIFT key and press 0. Then
press 4 followed by 4. Rotate the wheel, the readings
in the display window should change from 000 to 255.
If not check the shutter disc for blockage then check the
following voltages.
2.
When reading the voltages on the white & green
wires, turn the faceplate slowly by hand. The low volt-
age must be less than .7VDC. The high voltages must
be greater than 4.0VDC.
3.
Voltage readings are taken with all optical encoder
wires connected.
Lead Color
Voltage
Green to Violet (GND) - 2.4 ± .5VDC
Yellow to Violet - Less than .7VDC; greater
than 4VDC
Blue to Violet - Less than .7VDC; greater
than 4VDC
*Motor Circuit Testing
The following diagram will be useful when trou-
bleshooting the motor circuit of a 1004, 1050, or 6401
balancer (contactor style).
It allows you to troubleshoot just the motor using the
motor wiring diagram or the complete circuit using the
Forward or Braking diagrams. The readings may vary
slightly depending on your ohm meter but the three
readings should be consistently the same.
It may be useful to check the readings on a working
balancer so you will know what your meter reads
before trying to repair a nonworking balancer.
Solid State Balancer motors may be checked in a sim-
ilar manner by unplugging the motor connector and
reading across the three motor wires, you should have
the same readings across L1 to L2, L2 to L3, L1 to L3.
Remember to unplug the balancer before
using this procedure.
CAUTION
Direct Drive
Blk
Red
Red
AC
AC
+
-
OL
OL
Red
Blk
Blk
.45
.45
Blk
Red
OL
.45
OL
.45
Volt Leads
+
AC
AC
-
Typical readings,
your VOM
readings may
very slightly
Typical readings,
your VOM readings
may very slightly.
