The Nikon SB-900 Speedlight is a rather powerful flash unit. When fired rapidly, it can get hot. The flash has a built-in heat sensor called the "Thermal Cut-out" that is designed to protect it from overheating. The "Thermal Cut-out" can disable the flash for several minutes if it heats up from being fired rapidly. If you are shooting a wedding or important event, it may be a disaster to have the flash suddenly stop working. For this reason, Nikon has provided a means to override the "Thermal Cut-out," with the understanding that the warranty on a new SB-900 is void if the flash is damaged from overheating while the heat sensor is disabled. Let's examine use the menu system of the SB-900 to disable the "Thermal Cut-out."
Instructions
1. Turn on the SB-900 flash unit and wait a moment while it initializes.
2. Press and hold the "OK" button for about one second until the user menu appears.
3. Turn the "Selector Dial" (scroll wheel) clockwise and notice how the user's menu highlight bar moves downward. Scroll down approximately 14 clicks from the top of the menu until you highlight the icon that looks like a thermometer. To the right, you will see an On/Off menu selection.
4. Press the "OK" button once, and you will notice that the On/Off selection becomes highlighted. Turn the "Selector Dial" until you have "Off" selected and press the "OK" button to lock in the setting.
5. Press the small unlabeled "Mode" button (next to the green dot) under the "Exit" label. It is the first button on the top left, just under the LCD display. This exits the user's menu and places the flash unit back into normal operation. Now you can take pictures without the flash shutting off from overheating. The flash will warn you with an error message on the LCD and a beeping sound, if it gets too hot. Don't ignore this condition for too long or you may damage the flash unit and void the warranty.
Tags: Thermal Cut-out, flash unit, from overheating, user menu, fired rapidly