fredag 19 augusti 2011

DIY Nikon SB-80DX flash tube replacement

In this post I will explain how to replace a broken flash tube in a Nikon SB-80DX strobe. The tube used was bought really cheap on eBay and was said to fit the SB-600 and SB-800. They have about the same guide number as the SB-80 so it should be ok.

Tools you need:
A small electronics screwdriver
Soldering iron
Volt meter

Start with removing the two screws on the strobe head.
Then peal off the rubber covers on the joints on both sides of the head. Watch out for the metallic lever and spring which might snap out of its slot. There are four screws on each side holding the two halves of the head.

You can now take the head apart and reach the inner screws holding the cover of the capacitor. There are four screws on each side. Though, it is only necessary to remove the two screws marked with red arrows on each side.

To be able to disassemble the capacitor cover you have to remove the head from the body of the strobe. This is done by removing the four screws at the bottom of the strobe and two screws on the top. In order to reach the top screws you have to turn the head 90*.
The front cover of the body can no be removed and you will be able to pick out the head. By removing the four screws holding the metallic ring the cover of the capacitor can be lifted off. WARNING! You are now exposing the capacitor contacts which hold about 300 V. Beware not to touch any of the contacts inside the cover or you hurt yourself or damage the electronics of the strobe.

You should now drain the capacitor. This can be done through the volt meter by touching the capacitor pins with the probes, as is shown in the picture. However, if it's a digital volt meter it might take somewhere between an eternity and forever.
A quicker way is to use a discharging resistor between the two capacitor contacts. You may need to do this several times as the capacitor has a tendency to recharge spontaneously.
You are now free to continue working without the fear of being zapped.


To give yourself some space to work it's recommended that you remove the internals of the strobe head. Start by removing the two screws for the zoom flaps, to reach the screws holding the reflector device.

The flash tube zoom device can now be picked out and by removing the small press button PCB, the cover can be removed completely and you'll have better access to the flash tube.

The flash tube is held to the reflector only by three wires. If the tube is broken in half, like mine, you can just pull it out from each side and remove the solder. If it is still in one piece, you will have to remove the solder at one end first (preferably the end with only one wire) and then pull the tube out.


It's important not to touch the new tube while handling it or the grease from the skin will most certainly cause the tube to break prematurely. The easiest way is to use gloves but I didn't have any so I just held the tube by the small wire already attached by the manufacturer.
Solder the pin at the end with the wire to it's corresponding (white) wire. Insert the tube into it's holder without touching the actual tube.

Now solder the second pin to the pink wire.
Probably you should apply some melting glue for insulation of the tube pins but I didn't have any so I just left it as it was. Since everything is made of plastic I figured the risk of a short circuit should be minimal once everything is installed.
Finish off by soldering the third (white) wire to it's pin on top of the reflector device.

Voila! You're done. I would recommend to do a test assembly first, to make sure everything works, before installing all the screws. Also make sure there are no touch marks or dirt inside the reflector. This could affect the function and perhaps also damage the flash tube.
If the strobe works it's just to assemble everything in the reversed order.

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