Adding a 1/8" (3.5mm) Miniphone Sync Port
to a Speedlight Flash
I love my flashes, thanks in large part to David Hobby. One of the things that David is constantly promoting is his preference for using 1/8" (3.5mm) miniphone audio cords instead of the older, standard PC-sync cords for syncing flashes. PC jacks are notoriously unreliable as well as ludicrously expensive. Miniphone jacks are both more reliable and dirt cheap. Even better, the Cactus V4 radio triggers that I use come with 1/8" sync ports built in. Unfortunately, none of my flashes have them. One flash (a Sunpak 544) came with a proprietary jack; the other three (Vivitar 283, Canon 430EX flash, and Promaster 5200) could sync through the hot shoe only. When the Sunpak's jack started to flake out on me, I figured it was time to add a miniphone plug to all of my flashes.
I bought a 2-pack of stereo 3.5mm jacks at Radio Shack (274-0249) for $2.99. These jacks require a 1/4" hole to be drilled into the surface where the jack is to be mounted, and require about 3/8" of clearance behind that surface inside the flash. In the case of the Sunpak 544, my plan was to locate the miniphone jack right next to the factory jack and wire the two of them in parallel. For the Promaster 5200 and Vivitar 283, I added a new jack and wired it in parallel with the trigger wires on the hot shoe. The Canon 430EX has no room inside in which to mount a new jack, so it will have to make due with the hot shoe. Michael Bass makes new shoes for Canon flashes that have a miniphone jack already in place, and that seems to be the only way to add such functionality to the 430EX and 580EX Speedlites.
Of course, once you get these spiffy new jacks, you'll want to get some inexpensive 1/8" audio cables to plug into them. Check out these options from All Electronics and Deal Extreme for short cables, or this Y-splitter from Deal Extreme.
Before I begin the instructions, a word about safety. The capacitor that powers a camera flash stores a huge amount of current and dispenses it at hundreds of volts. Once charged, the capacitor will store this electricity for a very long time, even if you turn off the flash and remove the batteries. If you happen to touch the capacitor terminals, you'll experience this first hand. At best, the jolt will really get your attention. At worst, it could cause physical harm or (some claim) even death. If you've got a bad ticker or use a pacemaker, don't go anywhere near the inside of your flash. It's simply not worth the risk. If you're able to pay attention to what you're doing and avoid touching exposed terminals, then read on to find out how to add a sync port to various flashes. It should go without saying that this procedure will void any warranty that may still remain on your flash. I've performed this procedure on my own flashes, and it all worked fine, but I offer no guarantee that you won't screw something up and render your own flash unusable. It happens to the best of us. Proceed at your own risk.
If none of the photos on this page load, email me. I need to go kick my firewall.
Promaster FTD 5200
I performed this mod first on my cheapest flash, a Promaster 5200 for which I paid only $4. I figured if something went wrong, I wasn't out much, and my more powerful Sunpak 544 would still be usable.
The Promaster has a detachable foot that allows the same flash body to be used with different cameras. Interchangeable feet specific to each camera manufacturer can be plugged onto the bottom of the flash. It's a pretty slick setup for 3rd party hot shoe flashes in this age of iTTL/eTTL lighting. I merely removed this foot (press the button on the right side of the flash) and made my mod to it without having to mess with the innards of the flash itself and expose myself to the dangerous capacitors.
|Next, remove the four screws (two per side) that hold the top panel into the main housing of the foot.|
With the board removed, you can solder your jack to the same terminals as the hot shoe. The tip of the miniphone plug should go to the center pin on the shoe (white wire), and the base (collar) of the plug should go to the rim of the shoe (black wire). It's easiest if you solder your new wires to the terminals on the back of the circuit board. I highly recommend that you use stranded wire for this, not solid. These new wires will bend a lot when you're reassembling the flash. I used solid wire because it's all I had, and I had to resolder broken ends more than once due to the stress I inflicted. Before you reassemble anything, now is a good time to test your soldering by putting an ohmmeter between the hot shoe's center pin and the tip of a miniphone wire, and between the side terminal of the hot shoe and the base of a miniphone wire. You should have connectivity between those two pairs, but no others.
Sunpak Auto 544
My Sunpak 544 is the flash that really needed this mod, since the factory sync port was starting to flake out on me and sometimes wouldn't fire until I wiggled the plug. Armed with the knowledge of how the Promaster flash worked, I proceeded to dismantle my "potato masher."
Use a knife or tiny screwdriver to remove the "sync" sticker from around the factory sync jack. This will expose a small nut. Unscrewing this nut will release the factory jack to the inside of the housing.
Reassembly wasn't as straightforward as I'd have liked. There are some
slots into which the circuit boards must slide, and they don't like to
stay there until the case halves are nearly closed. Be sure that your
new wires aren't catching on any circuit board components during reassembly.
Don't forget to replace the stickers over your factory sync port and the
bottom of the handle.
This section was later reposted on the Prairie Rim Images blog.
The Vivitar 283 was the easiest of the three to mod. I'd previously added a box to the front of the flash that contained a dial to continuously vary the power setting of the flash. Read about that here. The terminal which that box used to connect to the flash also contains terminals to fire the flash, and the box itself had plenty of room to add a sync port to one side.
I haven't actually modded my 283 yet, but I expect it to be the easiest of the three. Check back later.
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originally written 1 Nov 2010