Troubleshooting Blank Screen / Display; Temporarily Switching From Closed Loop To Open Loop - Hitachi P1 Basic Instruction Manual

TROUBLESHOOTING BLANK SCREEN / DISPLAY

If the VFD's screen / display is blank it usually means the internal 24v power supply is shorted or damaged. In most cases if a
connected circuit is causing the short, disconnecting that circuit will restore 24v power to the screen / display.
• Check for power on the VFD's L1 and L3 input power terminals.
•
Disconnect the encoder wires from the VFD's main body control circuit terminals A, B, COM, CM1.
•
Disconnect all wires from the VFD's main body control circuit terminals related to 24v, (COM, P24, P-, P+, CM2)
• Contact Detroit Hoist for further assistance.

TEMPORARILY SWITCHING FROM CLOSED LOOP TO OPEN LOOP

In the case of an encoder failure, it might be required to switch from closed loop to open loop in order to lower a load.
DO NOT continue to operate the hoist in open loop mode unless for troubleshooting purposes without a load suspended.
Operating a closed loop hoist in open loop mode other than for the purpose of troubleshooting without a load suspended or lowering
a load is HIGHLY DISCOURAGED since all safety features will be disabled.
mode with a load suspended or the load may fall, use other means to remove suspended load.
To switch from closed loop to open loop change parameter AA121 = 08 SLV for high torque output.
No other parameters are required to be changed. All safety functions will be bypassed automatically, and the encoder limit functions
will be ignored. The brake release circuit will be switched over to the open loop brake control using brake release and set frequencies.
Function
VFD Control Mode
IMPORTANT! – If an E51 fault was occurring, DO NOT switch to open loop mode with a load suspended or the load may fall, use
If an E51 fault was occurring, DO NOT switch to open loop
Parameters
AA121
other means to remove suspended load.
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Value
10: Closed Loop Vector
08: Open Loop SLV