Danfoss VLT HVAC Drive FC 100 Service Manual page 99

6 Test Procedures
An incorrect reading here indicates the soft charge rectifier is shorted. The rectifier is not serviced
as a component. Replace the entire soft charge card in accordance with the disassembly proce-
dures in Section 7.
An incorrect reading here indicates the soft charge rectifier is shorted. The rectifier is not serviced
as a component. Replace the entire soft charge card in accordance with the disassembly proce-
dures in Section 7.
6
If all tests indicate correctly while isolating between the SCR/diode modules and the soft charge
card, the SCR/diode modules are suspect. Before reconnecting the cable at MK3, return to the
Main Rectifier tests and repeat those tests. Put the power card temporarily back in place to retest
the main rectifier. Replace any defective assemblies in accordance with the disassembly proce-
dures in Section 7.
Figure 6.7: Soft Charge Card Connectors
380–480/500V: Blue MOV & 8 PTCs
1
2
6-8
5. Reverse meter leads with the positive (+) meter lead to the positive (+) MK3 (A).
Connect the negative (-) lead to MK1 terminals R, S, and T in sequence. Each reading
should show open.
6. Connect the positive (+) meter lead to the negative (-) MK3 (C). Connect the negative
(-) meter lead to MK1 terminals R, S, and T in sequence. Each reading should show a
diode drop.
7. Reverse the meter leads with the negative (-) meter lead to the negative (-) MK3 (C).
Connect the positive (+) meter lead to MK1 terminals R, S, and T in sequence. Each
reading should show open.
1
MK1
MK2
MG.90.L1.22 - VLT
High Power Service Manual for VLT
2
3
4
525–690V: Red MOV & 6 PTCs.
3 MK4
4 MK3
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FC Series
Adjustable Frequency Drives