FLOW CHART NO.4 When the output voltage fluctuates. Does the secondary side photo coupler circuit operate normally? Yes Does the primary side photo coupler circuit operate normally? Yes Replace IC1001. FLOW CHART NO.5 When buzz is heard from the vicinity of power circuit. Check for short-circuiting of rectifying diode and circuit in each rectifying circuit of secondary side. (D1003, D1030, D1008, D1009, D1013, D1016, Q1002, IC1002, Q1007, Q1010, Q1011, Q1014, Q1004, etc.) FLOW CHART NO.6 The fluorescent display tube does not light. Is the supply voltage of 5V fed to pin(6) and pin(24) of IC2001? Yes Is the supply voltage of -24V fed to pin(15) of IC2001? Yes Is there 500kHz oscillation at pin(26) of IC2001? Yes Check the signal lines of FIP DA, FIP CK, FIP CS of IC2001 and IC601? Yes Are the filament voltage applied between (1), (2) and (38), (39) of the fluorescent display tube? Also negative voltage applied between these pins and GND? No No Check the EV 5V line. No Check the circuit and replace the parts. (IC1001, IC1006, D1048, D1015, etc.) Check the circuit and replace the parts. (IC1001, IC1012, D1024, etc.)
No
No Check the -FL -24V line. No Check R2001, IC2001 and their periphery.
Check or replace IC2001 and IC601.
No
Check the power circuit, D1017, Q2023, Q2024 and Q2025.
Yes No Check the fluorescent display tube and its periphery? FLOW CHART NO.7 The key operation is disabled. Is key switch contact and installation state normal? Yes Is the control voltage normally into the pins(3), (4), (7), (8), (9), (10), (11), (12), (13), (14) of IC2001? No
Check that the fluorescent display tube is free from damages such as crack.
Replace key switch.
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