Danfoss Turbocor TT Series, Service Manual

Page: 220 / 294

4.27 BMCC
The BMCC is the central processor board of the compressor. Based on sensor inputs, it controls the bearing and
motor system and maintains compressor control within the operating limits.
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The BMCC uses +5VDC, +15VDC, and -15VDC power supplied from the Backplane
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The BMCC relays compressor information over RS-485/RS-232 via Modbus communication
Figure 4-246 BMCC
4.27.1 BMCC Connections
The BMCC is connected to J2 and J3 on the Backplane. Refer to Figure 4-238 Backplane Connections on page 212.
4.27.2 BMCC Verification
4.27.2.1 BMCC Power Verification
1. Remove the Service Side Cover. Refer to Section 4.1.3.1 Service Side Cover Removal and Installation on
page 54.
2. Measure the voltages at the +15V, -15V, and, +5V test points.
3. Isolate compressor power and wait for the Backplane LEDs to go out.
4. Remove the BMCC from the Backplane.
5. Turn ON the AC input power and measure the voltages at the +15V, -15V, and +5V test points. The
measured voltages should be similar to those measured when the BMCC is installed.
4.27.2.2 BMCC Communication Verification
This section requires the use of the SMT. Refer to the Service Monitoring Tools User Manual for guidance.
1. Using the SMT installed on your computer, connect to the compressor using the Compressor
Connection Manager tool over RS-485 & RS-232.
2. If the system is able to connect, the BMCC is able to communicate with the user interface.
3. If the system is not able to connect, verify:
a. The BMCC is properly connected to the Backplane.
b. The I/O cable connection between the Backplane and the Compressor I/O Board is properly
attached.
c. The cable connection between the Compressor I/O Board (RS485 or RS232) and the user interface
(user PC or chiller controller) is properly attached.
d. Inspect Backplane for indication of damage.
Page 220 of 294 - M-SV-001-EN Rev. H 1/23/2023