Danfoss Turbocor TT Series, Service Manual

Page: 270 / 294

12. Verify the DC Bus voltage through the test harness. Refer to Section 4.21.2 DC Bus Voltage Verification
on page 167.
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If DC Bus voltage is correct, proceed to Step 13
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If DC Bus voltage is not correct, verify the SCRs
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If the SCRs pass test, replace the Soft Start, then repeat Step 12
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If one or more of the SCRs test faulty, replace all three of the SCRs then repeat Step 12
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If the 15VAC is present, proceed to Step 14
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If the 15VAC is not present, replace the Soft Start then repeat Step 13
13. Isolate the compressor power as described in Section 1.8 Electrical Isolation on page 22.
14. Remove the DC-Bus test harness and re-install the J2 (250VDC) and J3 (24VDC) (Potted DC-DC) or J4
(24VDC) (Open Frame DC-DC) outputs to the DC-DC Converter.
15. Install the top covers. Refer to Section 4.1 Compressor Covers on page 52.
16. Remove the Service Side Cover. Refer to Section 4.1.3.1 Service Side Cover Removal and Installation on
page 54. and remove the Service Side Cover.
17. Apply compressor power.
18. Verify the 250VDC and 24VDC test points on the Backplane.
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If both voltages are /- 10%, all supply voltages are good
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If either voltage is not /- 10%, proceed to Step 19
19. Isolate the compressor power as described in the Section 1.8 Electrical Isolation on page 22.
20. Wait for the LEDs on the Backplane to turn off.
21. Remove all connectors from the Backplane, leaving only the J6 (Inverter cable), J4 (250VDC) and J24
(24VDC) inputs connected.
22. Remove the Serial Driver, BMCC, and PWM. Refer to the following sections:
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4.26.4 Serial Driver Removal and Installation on page 218
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4.27 BMCC on page 220
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4.28.4 PWM Removal and Installation on page 228
23. Apply compressor power.
24. Verify the HV+ and the +24 VDC test points on the Backplane.
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If all voltages are /- 10%, proceed to Step 27
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If either voltage is not /- 10%, isolate compressor power and wait for the LED’s on the
Backplane to go out, then disconnect the J4 and J24 connectors from the Backplane
25. Apply compressor power.
26. Verify the 250VDC and 24VDC at the J4 and J24 DC-DC Converter output connectors.
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If either voltage is not /- 10%, replace the DC-DC Converter
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If all voltages are /-10%, replace the Backplane
27. Verify the +17V, +15, +5 and -15 VDC test points on the Backplane.
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If all voltages are /- 10%, proceed to Step 28
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If any voltages at the +17V, +15, +5 and -15 VDC test points are not /- 10%, replace the
Backplane
28. Isolate the compressor power as described in the Section 1.8 Electrical Isolation on page 22.
29. Wait for the LEDs on the Backplane to turn off.
30. Install all connectors.
31. Install the PWM, BMCC, and Serial Driver to the Backplane. Refer to the following sections:
Page 270 of 294 - M-SV-001-EN Rev. H 1/23/2023