Nikon SB-104 Nikonos Manual page 40

Heat alert light blinks.
When the interior of the 88-104 overheats
due to successive firing of the flash or
other factors, the heat alert light blinks.
Operation of the 88-104 stops
automatically.
- The flash can be used again after it has
cooled down and the lamp has stopped
blinking .
Electrical alert light blinks.
If one or both flash tubes did not fire, the
electrical alert light blinks to alert you .
-Bring the Speedlight to a Nikon service
center to have it checked.
+Note
40
Each time the flash is fired, the SB-104
checks to be sure both flash tubes have fired
normally. If both flash tubes fires abnormally,
the Flash Abnormal ity lamp blinks after firing.
If the lamp blinks even though the SB-104
has fired , one of the two flash tubes is
defective.
If the shutter is released before the ready-
light goes on , the flash will not fire and the
flash abnormality lamp will blink. However,
there is no abnormality in this case.