Topic: 24V reading is low
When using phantom power for high current draw Condenser Mics on Nions with all four I/O slots populated with ML II cards the +/-24V power voltage may drop a little. This is because on some Nions the 24V power supply current limit is slightly low. This voltage drop is sometimes sufficient to trigger the voltage warning: the ATTN button will flash, and pressing it will bring up the voltage monitoring screen, with the +/-24V measurements highlighted.
This voltage drop should not have any functional effect under most conditions, because the full 24V is actually substantially more than the cards require. The 24V supplies feed local regulators on the cards which generate a substantially lower voltage for the analogue i/o circuits - this decouples the analogue circuitry from variations in the 24V supply.
The problem can be worked around by using less power hungry microphones or by removing one of the ML II cards from the unit. If you can't do this, contact your local Nion service agent.