Vinman

Nikon D750 set to manual. Do I need to change any other flash settings. TTL, Command Mode Etc. To get it to trigger strobes.
(Should say Flash not Flask !!!)

Rick36203 Loc: Northeast Alabama

For a better answer, we probably need a bit more information about the equipment being used. If you're using a generic wireless radio trigger in the camera hot shoe, and a receiver is attached to the appropriate port on the light, all you need is to keep your shutter speed at, or below 1/200 sec., and the strobe should fire and the effects should be visible in your photos.

There are TTL studio strobes, but I believe they are a bit pricey, and should come with complete user instructions.

Vinman

Impact transmitter in hotshoe, Impact strobes. Works fine when I hit TEST and when I use Auto (it triggered the hot shoe). When I set to manual on camera it doesn't trigger the hot shoe.

Rick36203 Loc: Northeast Alabama

There should be no difference in Auto and Manual mode as far as "triggering" the flash with a radio unit in the hot shoe. If the D750 detects an active device in the hot shoe it will send a 'fire' signal when the shutter release is pressed.

If it does not detect an active device in the hot shoe in Auto mode (green), and the exposure needs flash, the camera will try to activate the pop up. At first I thought the pop up might be activating an optical sensor on your strobe in Auto mode, but it should not fire unless allowed to fully open. A faulty trigger that is not detected would block it from opening fully.

Make sure the trigger is properly seated in the hot shoe. Make sure the trigger and receiver are both on, and on the same channel/group.

I am assuming since this is your second thread on this problem, that the shutter speed in manual mode was at or below 1/200, and that the strobe was not firing at all in manual mode.