I have two Nikon SB-900 flash units that were both purchased in 2009. For years they both performed reliably, but about a year ago one of them started experiencing a power problem where the flash would turn on if the battery door was held just a bit ajar, but it wouldn’t turn on if it was fully closed. As I haven’t been doing as much photography as I used to, and I could always rely on a bunch of other Nikon flashes I own, or my Photogenic lights, it wasn’t a problem I spent a lot of time trying to fix. I did an initial search on the internet to see if it was a common problem, but came up empty.
Then last week while on location for a job, the second one started acting up in exactly the same way. So today I had some time to take a look at both of them again.
Doing an internet search this time I did come up with some hits that described the exact same problem. Only they didn’t have any solutions. But there were other people that had reported their SB-900s stopped working after batteries corroded the leads.
I checked the leads on both units and they appeared clean, and I had never experienced leaking batteries for these units, as I use rechargeable batteries (Duracell) in them and the batteries are usually taken out when I’m not using the flashes.
I decided to try cleaning the leads with a pencil eraser, and that’s all it took to get both units working again. Even though both units had bright shiny leads, there must have been just enough oxidation to prevent a good contact.
So if your SB-900s experience this problem, try a simple and quick cleaning with a pencil eraser before sending them back to Nikon for an expensive repair.