DIY: modifying the Yongnuo RF603N wireless remote flash trigger

Next guest post by Otto Peter is on how to modify the Yongnuo RF603N wireless remote flash trigger (available on eBay) to fit non-Nikon flash trigger sources, like light meters, or any camera with a PC socket

The Yongnuo RF603N is a nice, cheap wireless remote flash trigger for Nikon cameras. It does well what it is designed for, but its flash capabilities can only be used when it sits in the hot shoe of a recent Nikon camera. I want to be able to trigger my flashes from a light meter, from my F2, or maybe even from my Linhof (which, admittedly, I have not taken out of its case for a decade).

Each Yongnuo unit consists of two components: a shutter remote and a flash remote. Each component can operate either as a receiver or as a transmitter. The shutter remote is a receiver by default, it turns into a transmitter when you press the button. The flash remote is a transmitter when it's installed on a Nikon hot shoe (flash transmitter mode LED is on) and it's a receiver when it's not in a hot shoe. As a flash receiver, it outputs its trigger signal to its own hot shoe and to its PC terminal.

Obviously, what is needed is a way to switch the flash remote into transmitter mode without shoving it into a hot shoe. I said 'switch' because that's how I implemented it - with a switch: I did not want the flash remote component to be permanently in transmitter mode. I wanted the flash remote in its original condition in one switch position and to make it act as a transmitter that can be triggered from the RF603N's PC terminal in the other position. If you don't care about that, you can leave out the switch - see below.

Opening the RF603N is easy - there are just three cross-head screws. Circuit board, hot shoe, power switch, button and PC terminal are in the upper shell, the connector that goes into the camera's hot shoe is in the lower shell. The circuit board does not have to be removed, which simplifies matters, as the RF603N hot shoe and with it the upper shell is soldered directly to it. The bottom connector has three wires - ground (green), which is the hot shoe's metal frame, flash trigger (white), which is the large center contact and a control line (yellow), which goes to the small contact towards the lens. This last wire carries some digital signal from the camera to the flash and is pulled to 5V at least part time. I tried to connect it to the plus pole of the battery through a resistor (few kOhms) and it worked: the flash transmitter indicator LED of the RF603N lit up and I could trigger a flash on another unit by shorting the center contact of the connector to the metal frame (or white to green). Almost there. Problem: If the resistor is just connected to the battery, it will draw power even if the RF603N is turned off. I needed to find the power supply after the on-off switch and I found it - a thin circuit board trace coming from the right hole where that switch sits on the other side of the board:

Yongnuo RF603N before the modification

Yongnuo RF603N before the modification

Yongnuo RF603N after the modification

Yongnuo RF603N after the modification

Now we are ready to step through the modifications:

1 ‑ Find a suitable switch. Two poles and two positions are needed, and it has to be quite small. I used a Multicomp MC5SED1S105M2RES, available from Farnell for less than €3 in Europe (order number 2008805) and removed the metal clip and water proofing hood.

2 ‑ Cut and/or file a notch into the upper shell only (the one with the board in it). Don't destroy the circuit board! I kept the piece I cut away and glued it in as lateral support for the switch.

3 ‑ Carefully chafe away few square millimeters of the lacquer covering the power supply trace on the circuit board. Don't overdo it - it's easy to remove the trace as well.

4 ‑ Unsolder the center contact of the PC terminal and solder it to one of the poles of the switch. This is a thick wire, stiff enough to keep the switch from being pushed into the case but a bit short, so I added a bit of extra wire to bridge a millimeter or two. Glue some small pieces of plastic to the shell to keep the switch from sliding sideways - I used liquid, solvent based plastic glue.

5 ‑ Connect a resistor (33kOhms or 47kOhms) between the switch and control contact of the hot foot. Connect all wires according to the circuit diagram and photographs. I suggest using a thin, lacquer isolated wire for the connection between switched power and switch as it's more difficult to cleanly solder stranded wire to the thin trace on the board and the thin, supple wire does not rip off the trace too easily.

6 ‑ Close the case, see if it works.

I beg you not to over-estimate your abilities. It's easy to ruin the circuit board by cutting into it, ripping off a trace, or peeling it off with too much heat for too long a time. I do not take responsibility if you turn your RF603N into electronic garbage. That said, here is what you have to do with a transmit-flash-only unit:

1 ‑ Carefully chafe away some square millimeters of the lacquer covering the power supply trace on the circuit board. Don't overdo it - it is easy to remove the trace as well.

2 - Connect a resistor (33kOhms or 47kOhms) to the control contact of the hot foot. Use thin, lacquer isolated wire to connect it to the trace from step 1. I recommend not to solder the resistor directly to the trace as there is extreme danger of ripping off the trace.

3 - Unsolder the center contact of the PC terminal and connect it to the same board contact as the center contact of the hot foot (white wire) with a piece of wire. Be careful to prevent it from making contact with any other point on the board by putting a piece of electrical tape on the board.

4 ‑ Close the case, see if it works.

I have no idea about the Canon version of the RF603. It is likely that modifications are quite similar, but you'll have to check for yourself.

Disclaimer: I do not take responsibility if you mess up - judge your abilities realistically. And while I usually know what I am doing in the realm of electronics, there is always a chance for error - you modify your RF603N completely at your own risk.

Yongnuo RF603N schematic

Yongnuo RF603N schematic

Yongnuo RF603N switch drawing

Yongnuo RF603N switch drawing

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  • like diy tips
    thanks for posting

  • That’s the trigger I use!

  • Yusuf Yudhistira

    Use the YuongNo 602 then. It has separate receiver & transmitter. Not transceiver like YuongNo 603.

    • Otto Peter

      Seems to be an option – but… quote from the RF602 manual:
      Trigger through PC port
      In order to achieve this function, you need to purchase LS-PC/PC and AS-20.
      And then, there is this awkward, expensive CR2 battery for the RF600 transmitter. I prefer not to buy new stuff that is – I have been told – incompatible with what I already have, if I can fix it otherwise. And lastly, making things do what I want is fun.

  • Opinion…

    I’m interested in the Linhof bit of the description but I’m not sure if I have enough skill to implement all the changes. So does it mean that I could use Linhof (Technika IV) to trigger Nikon SB900 flash?

    • Otto Peter

      Of course you can – with or without modified RF603N. I don’t know what kind of shutter(s) you are using on your Technika, but they will all have a PC sync terminal (set to X if the shutter is ancient enough to provide a choice). You can either connect a sync cord from there to the PC terminal of the SB900 (side, opposite of battery compartment, under a small cover), or use the SB900 on one RF603N, and connect the shutter to a second, modified RF603N.

      • Opinion…

        It was very dumb of me to ask such a question knowing that the shutter in on the lens, not the camera but thank you for understanding:). I’ll try to modify one following your instructions. At the end of the day they are not that expensive. Thanks.

  • JD

    I’ll never buy that cheap shit again. I had four RF-603 receivers and one transmitter. I think the transmitter still work – but I can’t test it, since the receivers all died. Three of them died after the first photoshoot, the last one just died sitting on the shelf inside my apartment…. In other words: worst piece of junk I’ve ever owned in terms of photo equipment. AVOID at all terms if you don’t want to get burnt.

    • I gotta say, I have had completely the opposite experience. I have 4 RF603s as well. They work great, sturdy, never had a problem at all. Great range, reliability, battery usage the whole bit. I can’t believe how great a value they are. I don’t baby them, since I figure I can always just buy another pair, and they take the abuse well. Perhaps I just got agood batch! They’ve been banging around in my camera bag for 6 months, through weddings, commercial work and portraits, and they are still great.

      • JD

        Indeed doesn’t sound like my experience. Mine were reliable – on the first and only shoot they worked. Great range then, fired off reliably.

        I can still switch on every single one of mine – but they can’t fire a flash, and neither will they blink when signal is sent from transmitter. So, I’d guess the ones from my batch were built with cheap decaying components. Can’t see much other reason why the last receiver would just stop working while being stored in the shelf.

        I’ve been burnt enough to not waste any money down this hole anyway. It’s either pocket wizards or Nikon CLS from now on. Had it been 1-2 receivers out of 4 that had failed, I would have had some trust left. But 4/4 is just too bad.

        • Marco Santa Cruz

          might they all be on different channels?.. was looking to see if anyone trying this hack, and saw this comment.

      • JD

        Out of interest: when did you buy yours?

        I bought mine January 2010 and three of them died during a photoshoot already the same month. Noticed the death of the fourth one when I picked it up for some testing during the summer.

        • I bought mine January this year, off an eBay reseller out of newyork. Bright yellow packaging. Perhaps QC has improved dramatically.

  • photo-Jack

    Actually I was interested to buy a set of the Yongnuo RF603N but wasn’t really sure of the value of this equipment. As far as I understood there is no CLS transmission. And using the SB 9oos in a lastolite softbox or Umbrella I can’t even use any flash automatic since the flashes sensors are not turned towards the object and thus can’t receive the objects flashlight reflection.
    Bottom line I just get just radio triggering instead of an optical trigger, without being able to use any of these flashes automatics, right?

    Second though was about how to utilize off brand flash trigger equipment to make a Fuji X-Pro1 trigger Nikon Flashes using as much of the automatic functions of Nikon SB as possible. (don’t like to invest in Fuji flashes as I own a couple of Nikon SBs) Anyone have an idea?

    • Otto Peter

      Alas, you are right – no automatic exposure with Yongnuo remote triggers. That’s probably one reason why they are so cheap.

      I doubt that you can use anything but manual or A mode (i.e., the exposure sensor in the flash) with non-Nikon cameras. The communication between camera and flash follows a complex digital protocol (google for something like ‘nikon camera flash protocol’). Camera manufacturers protect their own business by carefully making theri cameras incompatible with flashes of other brands. There might also be patents lurking in the dark…

      • Otto Peter

        corection: no TTL automatic exposure with Yongnuo triggers – A mode is, of course, available

        • photo-Jack

          “A mode is, of course, available”

          As far as I can see, I can switch the SBs in A-mode, but it practically doesn’t work when the flash is used with an umbrella or softbox since the flash’s sensor then is receiving anything but the light-reflection from the subject. Thus practically it doesn’t work either, right?

          In other words, no need for sophisticated flash guns – every 100 bucks thing with sufficient power will do, since I’ve to meter each flash anyway and adjust fully manual.
          In this case I should be able to fire any SB with a X-sync port from any camera brand with a X-sync port, right?

          • Otto Peter

            I’d guess that any setup with more than one flash won’t work in A mode, and you are right about not needing high end flashes in soft boxes. Almost – it might be that reducing the power of a cheap flash changes the color slightly (less power -> more blue), but I could not find evidence for that in my SB900 specimens.

  • Spy Black

    I guess this is cool if like like to hack things up, but really a much simpler solution is to buy a $30 trigger set that will work with any camera. I use such triggers all the time to trigger multiple lights from any camera with a hot shoe or PC socket. Total cost of a 5-trigger system was about $100.

    • sultanabran1

      this is the solution i was going to use. i have a leica m9, i was wondering if any flash cord would do the trick?

  • Tom

    Thanks for sharing your expertise in adapting the RF603s.

    I would like to adapt a 603 to work for TTL pass-through, placing it between my Nikon D90 and a SB700 flash. I would also like it to trigger remote manual flashes at the same time.

    I’m confident in my ability to dismantle, solder and reassemble, etc, but would simply making all the pins connect through to each other work?

    If I could connect all of the pins, would this be likely to affect the ability of the 603 to trigger remote manual flashes? Could the battery life be affected.

    I would appreciate any information and am happy to risk turning at least one 603 into junk if there is a chance of success.

  • songo

    Many thanks for this post! It works like a charm and turns RF603 into something *really* useful. Kudos!

  • Steve

    I did the second method, turning it into a permanent transmitter so it would work with my Fuji X-E1. I probably got lucky with my shoddy soldering skills but it works just fine. Thanks for taking the time to post this.

    • Steve

      Should also add i had to remove all of the hot-foot pins except the centre one too

  • TesX

    I bought these 603 triggers for canon and noticed when trying out that there is no possibility to trigger by coord from an old camera.

    After reading this description I opened one of mine. The canon looks exactly the same in the interior.

    First I soldered a small wire to the Battery+
    I cut the connecting wires of a 120k-Ohm resistor and connected this with the wire.

    Then I decided that I no longer need the hot-shoe-foot and I cut off all three wires at the end there. It is easier to solder at the end of a wire than to solder at the small spots of the ground plate.

    I soldered the resistor to the yellow wire and made a first test.

    Yes. The trigger is now always *awoken*. Another test was to connect the white wire (trigger) with the green wire (ground) and this triggers the gear.

    Now I totally removed the wire from the PC-Connecter middle pin and I soldered the white wire there.

    After reassembling the device is now (and forever) only triggered by a coord in the pc connector and I am able to radio fire the flashes with my vintage equipment as long as there is a PC connector.

    I tested it with a Canon AT-1 and with a pre-war Super Ikonta and it works fine.


    • A_Beam

      Could you send me a picture of your soldering!? I want to do the same thing but I’m no good with electronics. Thanks.


  • A_Beam

    My god i did it. Thanks for the DIY! Works fine : )


  • Ben Di

    Hey guys

    I own the Sony Alpha 77 and 99 and bought those triggers together with the Yongnuo 560III flash which normally communicates with the RF-603. I made a modification connection the J6 with one side of the battery and a 130kO 0.6watt resistor in between. It works fine except that it can’t trigger the flash wirelessly. I have to mount the flash onto a RF-603 to fire it…

    Does anyone of you know if it would work with the solution above or does anyone have another solution?

    Cheers and thanks

    Benny 🙂

    • nbleak21

      I just completed this mod tonight… My fiancee purchased this trigger system when I still had nikon equip. and gave it to me for V-day, but since I’ve switched over to fuji over the past week, I decided do the mod. I can trigger my 560III wirelessly without having to connect it to anything. Are you sure that you have it on the right settings? (wireless slave trigger mode, and on the same channel as the trigger.)

      • Donavan Aarons

        What channel are you using? I am using sony and have the exact same problem triggering a YN560III from the hacked RF603. What channel are you using? What Is your exact dipswitch configurations?

    • Donavan Aarons

      Hi. I have the same problem have you solved it yet?

      • Ben Di

        Hi Donavan
        Yes I solved it 🙂 Yongnuo just released an updated version of their triggers, same price, and with them, I have no problem to fire the flash 🙂

        • Donavan Aarons

          Thanks, I also already ordered a set of version 2’s. I just wanted to know if I can get these to work while I wait. Can RF-603II trigger RF-603 one? Then Ill still have use for the old ones?

  • nbleak21

    Thanks, Otto!

    I received these as a V-day gift from my fiancee, but i’ve recently moved to fuji, so I figured it easier to do the mod, then deal with returning to amazon.

    Instead of hacking with a switch, etc. I just made it a straight transmitter by desoldering the J6 wire from the hot-shoe PCB, and ran the wire directly to the 3v+ (after scratching off the lacquer per your DIY,) soldered it in, and all is well! works with my second transceiver, as well as my 560III’s built in receiver!

    Thanks again!

    • Donavan Aarons

      I think you should be running a resistor in your connection

      • nbleak21

        I only run EneLoops in my flashes and triggers, which have a nominal voltage of 1.2v (2.4v in series) So I think I *should* be safe. I’ve logged approx. 10 hrs of usage since the conversion with no issues.

        Considering the above, would you still recommend running a resistor inline? If so, what ohm would you suggest?

    • Jim

      Hello sir I just want to ask if you just unsoldered the yellow wire from hot shoe and directly soldered to +3v source? without touching any other wires? im interested because Im using fuji also..thanks hope to hear from you.

  • Donavan Aarons

    Has anybody been able to successfully reverse this hack? I have now received my version 2 set and wanted to use my hacked one as a receiver again. I removed the resistor, but it will no longer trigger as a receiver. If I add the resistor againit still works in hacked TX mode.

  • I cracked the case on my Canon ones open this morning after realizing that I needed to make this mod. Wire layout looks the same so hopefully it will work out properly. I am really annoyed that this has to be modded to work like this since my friends all use the 602’s and have had zero issues with it.

    I am hoping to do this tonight and will let you know how it turns out.

    • It works perfectly well, although the resistors I picked up are pretty stiff and that trace is hard to solder too. The wire I bought was 22 gauge solid and probably overkill for what I needed but it was all I could find at Radioshack. Photo of the unmodified on the left and modded version on the right. I am looking for an epoxy or silicone sealant to hold the resistor from shaking.

  • RickGolt

    ok, i read through some of these comments but still couldnt figure out the solution to my problem. I am using a Yashica D and I want to trigger OCF with a Yongno RF-603N. I have a PC sync cord an it fires a flash when hooked from the camera directly to the flash. But no go when hooked to the trigger. I have tested the triggers and flash and they all work properly with my DLSR. Any suggestions or fixes for this problem. I have searched the internet at great lenght for help and this is as close as I have gotten.

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