Why is the ATS48 integral display (on the front of the Soft Starter) blank?


28 July 2022

ATS48 integral display is blank

Product Line:
Altistart 48

All models

Integral red LED display does not illuminate.

Follow the troubleshooting procedure below.

Is there control power?

Measure CL1 - CL2 for 90 - 270Vac.

Blown fuse? May indicate a shorted power supply on the power board or a problem with other devices (relays, pilot lights, etc) connected to the control power.

Measure DC Voltage between +24V - COM.

If 24VDC supply is OK (24VDC +/- 25%):

  1. Remove power from the Soft Starter.
  2. Remove the control board to gain access to the power board. Verify that all wire plug connectors are seated properly. 
  3. Pay particular attention to the flat ribbon cable that connects the control board to the power board.   If this cable is loose (usually at the power board), it can be reconnected by first ensuring the collar (see attachment) is loose, then insert the ribbon cable and "snap" the collar down to hold the cable in place.
  4. Reinstall control board and apply power to see if the display now works.

If 24VDC is not OK:

  1. Remove power from the Soft Starter.
  2. Remove the control board to gain access to the power board.
  3. On the power board, unplug the connector at plug J6.  This is the connector with 4 wires on it, 2 pair, both white and black.
  4. Apply voltage to CL1 and CL2.  Be sure to use appropriate PPE.
  5. At the J6 plug, measure pins 5-6 for 24Vdc, +-25% ( used for local display ). Measure pins 1-2 for 10Vdc ( used for the remote display).
If either power supply is bad, replace the power board, part number based on ATS48 unit. It is also recommended to replace the control board as well, VX4G481, if a surge is the suspected cause of power board failure.

If J6 measures good, and the ribbon cable is properly installed but the display remains blank, replace the control board.
If another ATS48 is available, you could verify there are no other issues in the Soft Starter by swapping control boards.
Note that the programmed parameters are stored in the control board, so changing or replacing the control board will require reprogramming.

See attached file for the wide ribbon cable connection port on the power board.