TDK-Lambda LC1202, Instruction Manual

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83494001 Rev H Page 20 of 27
6 MAINTENANCE AND TROUBLESHOOTING
6.1 SAFETY PRECAUTIONS
The calibration and troubleshooting steps described in this section require operation of
the power supply with the top cover removed. Proceed with extreme caution as hazard-
ous voltages are exposed throughout the unit. Safety glasses must be worn to prevent
serious injury in the event of a component failure (e.g., power transistors readily explode
during fault conditions).
6.2 CALIBRATION
Calibration of the output is accomplished with trim pots located on the Control Board.
This pc board is horizontally mounted on top of the high voltage output assembly on the
right side of the unit as you face the front panel.
6.2.1 OUTPUT VOLTAGE LEVEL:
RP14. Slowly adjust clockwise to increase output voltage for a given V
PROGRAM level. Factory set for 10V = rated voltage.
6.2.2 OVERVOLTAGE TRIP POINT:
PP17 (12 turns). Slowly adjust clockwise to increase trip point. Factory set at
10% above rated voltage.
6.3 MAINTENANCE
No maintenance is required under normal operating conditions. Occasional vacuum or
blowout of the chassis may be required when operated in extremely dirty environments.
The oil-filled HV assembly must not be opened. The oil and components have been
specially cleaned and vacuum impregnated at the factory and the assembly hermetically
sealed. Opening the assembly may compromise performance.
6.4 TROUBLESHOOTING
First check for obvious trouble such as input power, output connections, control connec-
tions and signal levels. In particular, the interlock, the INHIBIT and the ON/OFF signals.
If there is no load connected, the power supply will sense an open circuit and immedi-
ately shut down indicating a LOAD FAULT. If there is a short circuit or overload condi-
tion on the output, the power supply will operate in a 50% duty cycle protection mode
and indicate a LOAD FAULT. An overload condition can occur if the INHIBIT signal is
missing and the discharge rep rate is too high to allow the capacitor to fully charge to V
PROGRAM.

If the power supply is making high voltage but does not appear to be functioning
properly in a specific application, the problem may be application related. Consult
the TDK-Lambda Americas Inc. customer service department.

If the power supply is not making high voltage, the problem is usually either failed
HV output diodes or a problem on a pc board. Refer to the schematics provided in
this manual.

Check the DC bus voltage on the SWG C1 - C2 and SWG C3 - C4 on Inverter
Board. Should be 250-350 V.

Check for failed power transistors or diodes on the Inverter Board.

Check the +15V and -5V on the Control Board.

Check the output and inputs of the main OR-gate U2-2, 3, 4, 5 and u11 pins 3
and 4. A high level will disable the power supply.

Check the output of the latches U28-1, U31-1, U37-1, U12-1 and U41-1.