This means that the input voltage on one of the receivers is beyond the acceptable range of the A/D converter. Try lowering the current output of the SuperSting™, lowering the voltage of the transmitter or increase spacing.
How to lower the current output of the SuperSting™:
Go to Menu 6. After entering this menu, press 1 on the keypad.
How to lower the voltage:
Go to Menu 6. After entering this menu, press 4 on the keypad.
Change Electrode Spacing, current or voltage:
Increase narrow (<<1m) electrode spacing or lower the current or voltage
NOTE: There are 3 error codes your SuperSting™ can generate: HVOVL, TXOVL, and INOVL