Danfoss Turbocor TT Series, Service Manual, Page: 115 / 294

Figure 4-96 Open-Top Soft Start Connections
Table 4-23 Open-Top Soft Start Connection Identification
No. Component
1 J7: Soft Start Temperature Sensor connector
2 J3: Thermostatic Fan Control connector
3 J1: AC Inputs
4 J8: DC Link
5 Ground
6 J2: SCR Gate Signal connector
4.14.2 Soft Start Verification
4.14.2.1 Verifying Soft Start Voltages
1. Before verifying Soft Start voltages, ensure that the correct 3-phase main AC voltage is present at the
Mains Input terminals.
2. Using the DC bus test harness (refer to Section 1.10 DC Bus Test Harness Installation and Removal on
page 25.) with power applied to the compressor, verify that the expected DC bus voltage is present for
the application. Refer to Table 1-2 Expected DC Bus Voltage on page 29.
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No DC voltage may indicate that the Soft Start is not controlling the SCRs, or an open fuse on
Closed-Top Soft Starts
3. Using the DC bus test harness with power applied to the compressor, verify that the 15VAC to the DC-
DC converter is present. Output can range from 12 – 25VAC, depending on primary input voltage.
(Closed-Top Soft Starts only)
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No 15VAC may indicate an open fuse on Closed-Top Soft Starts
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If the 15VAC supply is not present at start-up, the Potted DC-DC converter will not function
M-SV-001-EN Rev. H-1/23/2023 Page 115 of 294