Homemade 5-pin Olympus Flash Connector Plug

Many of the Olympus digital cameras (C2100, C700, etc.) have a 5-pin connector for attaching an external flash, but the proprietary Olympus cables are prohibitively expensive, at least in my region. Typically an FL-CB04 is used to connect a non-dedicated external flash, and I was wanting a cable similar to this, but with a 2.5mm phono connector on the end.

My first attempt used a cut-down mini-din connector, but this could only allow connection to two pins of the socket, and so was not mechanically robust, but did work adequately.

The connector described here is much better, and also easier to make. It is based on 5 standard turned-pin wire-wrap socket pins. These could be extracted from a socket strip or a wire-wrap IC socket (an 8-pin socket would give a few spares). You would use standard solder pins (not wire-wrap), but these are a lot shorter and so harder to handle.

The Method

If the IC socket connection is deeply recessed, it may be a good idea to file a bit off the top of the socket strip before removing the pins. That can also be done individually later, or on the final manufactured socket.

After removing the pins from the plastic socket, the top lip of each then needs to be turned down to match the diameter of the body of the pin. This is easiest done by inserting the base of the pins into a small drill, and then running it gently against a file. It is working like a lathe, so you want to keep to a fairly low drill speed. The type of drill or pin-chuck used to drill PCB holes would likely be appropriate. Doing it this way, it would only take a few minutes to do them all.

Once the top lips are removed from the pins, they can be inserted into the connector on the camera. With the socket pins in the connector I then soldered them all together at the ends of the pins so they would be held in position. If you do this, make sure the camera is off, and be careful not to transmit too much heat into the camera connector. Once this is done, you have a group of 5 pins connected that can be inserted into the socket in the camera. They should not touch at all except via the solder join.

After they are joined, the pin area of the connector can be potted in epoxy. I placed some heatshrink around the thick section of the group of 5 pins and gently shrank it to fit. Then I placed the connector with holes-down, onto the top of a glue-stick. (That's a glue stick designed for gluing paper together) The glue-stick forms the bottom of the mould, and other materials such as wax could equivalently be used. You mainly need to ensure that epoxy does not enter the pin shafts.

With this arrangement in place, the heatshrink can be filled with epoxy to form the plug body. 5 to 10mm of depth should be adequate. I don't recommend individually heat-shrinking the pins for the whole depth because the epoxy may not stick as well to them. Once the epoxy had set, I was easily able to remove the large heatshrink that formed the mould

Once the epoxy is set, you can de-solder or cut off the ends of the pin tails, so they will no longer be electrically connected. The cable can then be soldered to the two appropriate pins. I made mine a right-angle entry so that it wouldn't interfere with my nose when using the right eye in the viewfinder. I had the cable pointing to the base of the camera, and this also serves to indicate the correct plug orientation. Note though that different olympus models may have the socket oriented differently, so if you use it in different cameras, you may want to go to a bit more trouble in the epoxy moulding stage so that it will only fit in the correct orientation.

After soldering the cable, more epoxy can be cast in place to form the connector shell and cosmetic heatshrink could also be added.

Connections

All 5 pins of this connector may be connected, but for a normal flash sync you just need two of them. These are the two shown in blue box to the left of the connector. The other three pins are for TTL communications, and some guesses at their usage is also shown. They are only educated guesses though, and there is a big job ahead if you want to make use of them anyhow. The side view of the C-2100 is given. Use the location of the three locating lugs to determine the pin definitions in other camera models.

Acknowledgments

Mandatory disclaimer: Remember if you try following these instructions, you do so at your own risk and I am just describing what I've done. If it breaks your camera, you get to keep both pieces.