Stereo Sweetener for a 1/8" Sync Mod

A Strobist reader who cryptically goes by "bleeblubleeblah" last year posted may what well be the nicest walk-thru to date of hacking a Nikon SB-600 speedlight to get a remote 1/8" sync jack.

And as sweet as that looks, someone has hacked the idea to make it significantly better.

How to improve your 1/8" DIY jacks, inside.

Nikon omitted the crucial external sync jack on the SB-600 and then did it again on the new, more expensive SB-700.

But then reader Edward Morris steps up to the plate a couple weeks ago and improves the above mod with one simple step: Connecting the unused third wire from the stereo 1/8" jack to the TTL "quench pin" of the SB-600. This makes the flash both externally synchable and able to have its power controlled remotely by the RadioPopper JrX Studio triggers.

Before you click over to the how-to discussion page of the two mods, understand this: If you do not know what you are doing, crawling around under the hood of a speedlight can be dangerous. This is because of the potentially high voltages stored in the capacitor even when the flash is turned off.

Which is to say that getting zapped with 350v from a capacitor can quite literally shock the crap out of you. Or worse.

But if you are a solder junkie and want to try it, it is here. This "third rail" mod, for lack of a better term (and to extend the danger metaphor) is possible on many flashes. Most TTL models except for the newest ones work on the quench pin principle. (Sadly, my guess is that the SB-700 is like the '900 and will not.)

But if your flash uses the TTL quench pin and you want to get full usability from Studio JrX's without the RadioPopper add-on hot shoe jacks, it is a pretty sweet setup.

Not a solder junkie? If you have an SB-600 (or any other, jackless flash) and want to mod it externally with little to no danger, check out this AS-19 foot PC mod post from the archives.


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Blogger testing said...

you can also mod all chinese made vivitar 283s to work with radiopoppers jrX. I have made three now.

November 04, 2010 3:47 AM  
Blogger scott-c said...

I use these hot shoe syncs with a jack ( from this store ( Perhaps they too could be modified. Also, to power your speedlight you could use one of these power packs that takes 8 x AA batteries (

November 04, 2010 7:31 AM  
Blogger Joe Holmes said...

Cool! But Radio Poppers -- and not my Pocket Wizards?

November 04, 2010 7:40 AM  
Blogger Two Jack Studio said...


I actually have an SB-600 and have always used a hotshoe to PC adaptor. This makes it much better.

Now, if you can show me the same kind of mod for my Metz 44-AF4C, which I cannot get to fire off camera at all, then I'd be really happy.

Thanks D, you're awesome!

November 04, 2010 7:49 AM  
Blogger James said...

Nice modification, looks like it came from the factory that way (which it should of, and on the 700)

November 04, 2010 8:17 AM  
Blogger Dashney said...

How sad is it that you have to do sub $5 mods to drastically improve pieces of triple digit tech? I had to glue a 4 cent washer around the protruding buttons of my Skyport triggers and receivers to keep them from draining themselves in my bag. I'm literally very close to going the Honl route and putting out my own line to stop some of the insanity. $10 - $15 (in Canada) for a spigot?!

November 04, 2010 9:43 AM  
Blogger Aaron said...

I've been using something similar for a little over a year now:

Take a Nikon AS-E900 and a small stereo jack. Remove the screws from the hot shoe, and remove all of the internals, leaving just the 3 wires that go to the contacts on the top of the hot shoe. A soldering iron is helpful to remove the extra wires.

Cut the "wings" off of the stereo jack, to make it smaller, and solder the contacts to the 3 wires on that go to the jack (I don't remember the color codes off hand, but the quench pin goes to the ring on the jack). Use heat shrink tubing to cover the exposed contacts. Put the halves back together, and put the screws back in. There will be two holes left from the second port and the cord. Use one of those to fill the inside with epoxy, to hold the jack in place. The result: a Nikon AS-E900 hot shoe with 1/8" TRS jack, which will allow remote power control for any flash except the SB-900, for around $8.

November 04, 2010 10:35 AM  
Blogger freak said...

I have put stereo jacks into 4 Canon 540ez flashes. These flashes only do aTTL and not eTTL - ie they are not compatible with Canon's digital line up. The 540ez can typically be found for $80-$100 and their power can be decreased to 1/128. I know I wasn't the first to do it. Great flashes, great build quality, and there are always some available. Again I've never paid more than $110 for one of them, so I have 4 manual flashes that can be triggered from my CyberSyncs that I got for about $400. I love Strobism.

November 04, 2010 11:20 AM  
Blogger Doug said...

Forgive the obvious, but can't you just remove the batteries to eliminate the risk?

November 04, 2010 12:10 PM  
Blogger David said...


Capacitors carry a grudge even after being removed from a power source. And your finger will make a fine discharge circuit in a pinch.

November 04, 2010 12:45 PM  
OpenID Goode Photography said...

I did this as soon as I saw this post this morning. Works perfectly!! Thanks for the link and the info David! :-)

November 04, 2010 4:14 PM  
Blogger Edward said...

oh wow, that's me..... haha... cool
you can modify any flash from any manufacturer that uses ttl quench to work this way, assuming you can fit the miniphone jack inside the case, some digital Vivitar flashes even have a three pin jst connector on the front of the hotshoe that I suspect may be used for this purpose, I'm not positive though.

I have also used the AS-E900 and i like them, probably even more than opening the SB-600, I only opened this one because it was out of warranty

November 04, 2010 7:18 PM  
Blogger Tom said...

That's beautiful and elegant! I wish I weren't afraid of opening my SB600 and breaking it. So for others folks like me - afraid of cracking open electronic stuff that's working. I did a DIY for an external RadioPopper Cube that provides TTL power control. Its really just documentation of what others with more smarts than me put together in the Flickr Discussion groups but it's an easy alternative and doesn't risk touching the "third rail". Here's the link for anyone that would like it. RadioPopper cube DIY


November 04, 2010 9:33 PM  
Blogger Che said...

Just did the Mono Version of this mod to 2 SB600s Now I need some pocket wizards.
High Voltage DC hurts but won't do any serious damage to you. What you need to be very very careful of is shorting out the capacitor with a soldering iron or screwdriver or anything metal. That voltage on a capacitor could easily weld the tool to what ever it touches and fry lots of electronics in the process.

November 04, 2010 11:05 PM  
Blogger Bieber said...

I did this to my SB-25 and SB-26 a couple months ago, and it's great. In those, I had a lot of trouble finding a place to put the jack, so I finally settled on ripping out the auto-flash sensor in the front, drilling a hole in the plastic cover there, and mounting the jack behind it. My next project is to build the circuit to make them work with Canon strobes and mount it inside my 580EX along with a 3.5mm jack, if it'll all fit.

And to the guy who said that the capacitors in the strobes won't hurt you: yes, they will. Before working on mine, I always do a full-power pop and immediately open the battery lid (I keep it slid out and pressed down while I push the button) so they can't charge back up much at all. If you're ever working around the capacitor itself, discharging it with a high-impedance resistor would be a very, very good idea.

November 05, 2010 12:16 AM  
Blogger freak said...

@Che + others
When modding one of my 540ez flashes, I left the power switch on with the batteries out. I found out the hard way about capacitor discharge. On the 540s it appears as if I was able to release the charge just by looking at it, not to mention touching it with my finger or a small screwdriver. I did both :s

November 05, 2010 10:01 AM  
Blogger Obi-Wan said...

Cool writeup. I did similar mods to a few of my off-brand flashes just recently. You can read about it and see pictures here:

November 05, 2010 11:46 AM  
Blogger Aaron said...

After my previous comment, I had a request to document how I put a 1/8" jack inside a Nikon hot shoe, so I wrote it up. It can be found here.

November 05, 2010 10:52 PM  
OpenID Zack said...

Any idea on whether power from these modded flashes can also be controlled remotely with a Cyber Commander?

November 07, 2010 10:09 AM  
Blogger Edward said...

the cyber commander can only control flash units with the paul c buff control port, someone may figure and adapter eventually but there isn't one now as far as I know.
The standard cyber sync receivers with the miniphone jack will trigger a flash unit modded this way but will not control it

November 07, 2010 8:24 PM  
OpenID Zack said...

@ Edward
Noted. Thank you Sir. I realize I was hoping for a lot, to be able to control the output on a bunch of different stuff with a single controller.

November 09, 2010 8:11 AM  
Blogger MaCanuck said...

Question for Testing (or anyone who had got the 283s working with the RPs): what are you doing? Trying to get this to work and it is not....

November 28, 2010 6:51 PM  
Blogger Paul Adams said...

I hope this isn't a stupid question -- if I do the "stereo" modification, for the possibility of using a RP JrX system in the future, will I still be able to use a "dummy trigger" (like a PW, Cybersync, etc.) that only uses a "mono" cable? In other words, will there be a problem having the "quench pin" and the negative (rail) contact essentially jumpered?

Side-note: if you can locate the large capacitor inside the Speedlight, I think a safe way to discharge it is to get a decently high-resistance resistor (not sure what size you should use, as I don't know the capacity of the capacitor) and put it across the cap (side A of cap to side A of res, side B of cap to side B of res).

December 23, 2010 2:34 PM  
Blogger Edward said...

@ Paul Adams
no problem using dumb sync on the stereo jack, the two channels are not actually bridged when you insert a mono mini phone jack anyway

December 23, 2010 4:01 PM  
Blogger Paul Adams said...

@Edward -- Are you sure about this? I bought a stereo jack and inserted a mono cable, and my meter shows that the ring and shield contacts are thus jumpered.

Anyway, since it seemed like having the quench pin always tied to ground would be the best way to have my flash not fire, and I still wanted to have the ability to do either a dummy trigger or the power-adjust (via quench pin) at some point in the future, I added a toggle switch to the bottom of the flash and made it recessed enough that it would take an effort to toggle.

December 27, 2010 11:09 PM  
Blogger Edward said...

While it can sometimes be possible to jimmy or twist the jack such that the two poles touch they shouldn't under normal conditions... in any case the toggle switch probably protects against any weird malfunctions.
I have used a mono-miniphone cable to dumb sync a SB-600 with a stereo-miniphone jack embedded

December 27, 2010 11:43 PM  
Blogger Paul Adams said...

@Edward -- With due respect, I think the ring and sleeve of the stereo connection will be normally connected when a mono cable is inserted. See the Wikipedia page (about 1/3 down the page):

I posted the pix of my SB600 and SB800 mods with the 1/8" jack and switch:

January 01, 2011 5:14 PM  
Blogger Edward said...

hmm, very interesting. In any case your implementation of the switch into the hot-shoe is quick thinking and pretty slick.

January 02, 2011 12:44 AM  
Blogger Greg in Fort Mac said...

WARNING: I did the mod on an SB600, just after It fell over on a lightstand and broke/bent the shoe. The modded flash seemed to work using a PW PlusII plugged into the jack; then I sent the flash to Nikon Canada to have the bent shoe replaced. THEY WOULD NOT REPAIR THE FLASH. They said that since I had performed a customization on it, they could not assure me that they could return it to factory specs after the shoe replacement, so they wouldn't touch it.

January 06, 2011 10:56 PM  
Blogger Paul Adams said...

@Greg -- Good to know. I guess I'm not completely surprised. If you wanted to replace it yourself, you could get the part here: (SB600 foot assembly) for $50.

January 13, 2011 12:09 AM  
Blogger Rob said...

I know this is WAY after the fact, and not exactly on topic with this post, but I had a question about the SB-600 itself. You know those two copper (or gold, I dunno) contacts on the bottom, right next to the actual hot shoe plate? What on earth are they for? I've scoured my manual and the internet, and have no idea. I thought they might be for an external power pack, but when I've looked for them, they don't seem to exist. Any information would be much appreciated in alleviating my OCD, here.

July 31, 2012 4:49 PM  
Blogger Edward said...

They power the AF assist light in te sc-29 remote cable

July 31, 2012 8:14 PM  
Blogger Rob said...

@Edward, thanks for that. Now I know the only way to use external power is to mod it.

August 01, 2012 8:44 AM  

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