A few things can happen based a search of discussion threads on flickr strobist group.
- It will not power up.
- Flash powers up ok but it will not fire due to broken flash tube.
- Zoom head gets stuck.
- It keeps firing non-stop.
Many, including me, have come to the conclusion that the SB-600’s are fragile. Mine was recently knocked off a table and landed on oak floor hot shoe first. There was no sign of damage and I didn’t become worried until I couldn’t turn it on.
Since the warranty period was over, I decided to check it out myself. There wasn’t anything loose inside. Nothing appeared broken. Batteries made good contacts. Flash tube was intact. Without time to waste, I decided to send it to Nikon USA for service. The estimate for a service repair rank B2 (moderate repair with major parts replaced) came out to be $97 + S&H. It was an expensive repair but perhaps OK since it was only about half price of a new SB-600. So I authorized the repair.
When I received the flash back from Nikon service center in California a few days later, I was also sent a copy of invoice. A detailed list of repairs and adjustments were shown, including a line item that says “RPL MAIN PCB”. It is difficult to believe the surface mount components on the main circuit board will break since they are so light. Most likely the impact from the drop broke a Cu trace or a connector somewhere.
At the end, I have nothing more than this: Be careful with your SB-600 and don’t let it drop.
Keywords: Flash photography, Nikon, SB-600, Speedlight