Frigidaire LGUB2642LF2, Service Manual

Page: 40 / 187

Electronic Control
3-18
Variable Capacity Compressor
Electrical Components
The new series of very high efficiency compressors are
equipped with a new electrical power input electronic
control, also known as the Inverter, to replace the
standard start package. The solid state power input
electronic control (Inverter) contains:
1. Low voltage power supply.
2. EMI Filter and Voltage Suppressor Circuit.
3. AC-DC Converter
4. Three-phase Inverter Bridge
5. Serial communication.
6. Microcontroller or DSP Controller Protection.
7. Voltage Sensor
The Inverter replaces the solid state relay, the overload
protector and the run capacitor. The Inverter has 115
Volt AC current supplied to it whenever the refrigerator
is connected to line voltage through the service cord.
The inverter receives a DC signal from the main control
board located under the refrigerator in the left front
opening behind the bottom grill.
To Check/Replace the Inverter
1. Use your Multimeter or a good volt meter set on 300
volt AC to test the voltage going into the inverter
from the product service cord. Do not disconnect
the molex connector. Slide the probes from your
meter along side the wires until you connect with
the terminal itself. You should read 115 or 127
(depending on local codes) Volt AC +/- 10%. If
less, check service cord and supply voltage.
NOTE: It is recommended for best results that the meter
used for this test is a TRUE RMS MULTIMETER. A
voltage test for both the RMS Meter and a standard
Multimeter will be provided.
2. Remove the lower power board from under the
front of the product. (See Section 6 for detailed
procedure). You will use connection J2 terminal 3
(RED/BLK) and terminal 4 (BLK/WHT) on the lower
control board to test the voltage. (See Figure 3-9)
Do not disconnect the molex connector from the
board. Slide the probes from your meter along side
the wires until you connect with the terminal itself.
Set your RMS Multimeter to DCV/HZ setting. You
should show from 50 to 155 HZ on the meter.
With a standard Multimeter, first set the meter on
ACV. You should show 10 to 15 Volt AC. Next set
your meter for DCV, you should read 2 Volt DC or
less. If voltage is outside the listed range, replace
the main control board. If the voltage is good
proceed to step 3.
Low Voltage
Power Supply
EMI Filter and
Voltage Suppressor
Circuit
AC-DC
Converter
Three Phase
Brushless DC
Motor
Three Phase
Inverter Bridge
Voltage
Sensor
Microcontroller or DSP Controller
Protection, sensors, arithmetic,
communication, additional functions
Serial
Communication and
speed reference
To electronic circuit
Double or Basic Insulated
DC Voltage output
Applicable Standards
50/60Hz
AC Input
Power Limit,
Over-current Protection
DC
Voltage
1
2
3
4
Red/BLK
White/BLK
J2
Figure 3-9
Figure 3-10