Points in Focus Photography

Control TL PocketWizards and Canon 580EX II Flashes


I’ve received at least one email, and now a comment about sudden flash death induced by or related to LPA design’s Control TL PocketWizards. Moreover, a recent post on Canon rumors has a link to a paper, purportedly produced by LPA Design employees summarizing their investigation into flashes failing.

LPA design claims to have received reports from 120-140 customers that their 580EX II flashes, has been damaged within the past 18 months with similar symptoms. The symptom specifically is the inability for the damaged flash to produce controlled bursts. Lacking the ability to control the output, the flash will make a full power discharge all the time, even for TTL pre-flashes.

TLDR, The Brass Tacks

  • The potential exists with at least Canon’s 580Ex II and possibly Nissin’s Di866 (I’ve received a report of a Nissin Di866 being fried in a similar manner) flashes that a failure can occur.
  • The failure doesn’t appear to be related to heat buildup, so AC-5 soft shields aren’t a problem.
  • The failure appears to be strongly related to an electrical arc formed between the flash tube and the flash’s reflector, eventually frying the controller.
  • Replacing the fired controller, doesn’t fix the problem, and the flash will die again, even if it’s never used with a PocketWizard.
  • LPA Design claims that failures have happened to less than 0.5% of the MiniTT1/FlexTT5 units, and less than 1% of 580EXII flashes connected.

From my interpretation of the LPA design report, the problem lies in the flash and not the PocketWizards.

Moreover, it seems that if your flash exhibits defects that lead to the failure use becomes a consideration. In LPA Design’s tests, the arcing occurred randomly, even in HSS discharges where you would expect to see it in every “pop”.

Finally, it’s entirely likely that as many 580EX II flashes are failing on users who aren’t using PocketWizards at all, but we’re not hearing about it since they either aren’t being used as much or simply are being considered a case of random broken equipment by the users.

A Deeper Analysis

The LPA investigation tracked down the problem to 2 main areas. First, the failure is ultimately noticed when the insulated-gate bipolar transistor (IGBT) that controls the actual flow of current to the flash tube dies. Secondly, it appears that the IGBT dies due to repeated arcing between the flash tube and the reflector behind it.

Before I go any further, I want to take a moment to talk about how this stuff all works. The IGBT is used like a switch. It allows the flash’s onboard microprocessor, which run at considerably lower voltages, to accurately and quickly start and stop the flash’s discharge as needed without being fried. The IGBT is designed for this kind of work.

The big picture view is something like this. The camera or Control TL PocketWizard, talks to the flash using a defined set of signals, this is the ETTL protocol. These signals could say things like “set power to 1/2” or “Fire.” The exact meaning of these signals is defined by the protocol, and this is what everyone has to reverse engineer to produce Canon or Nikon compatible flashes.

The diagram below shows a simple example of how this plays out in a flash during a full TTL pre-flash and exposure cycle. The diagram shows time progressing from top to bottom. The first set of arrows (from left to right) represent the TTL commands sent to the flash by the camera. The step wave form under IGBT drive voltage, shows the control voltage applied to the IGBT by the microprocessor (this maxes out usually between 2.5 and 4 volts, and switching several 100 volts). Finally, the curvy lines on the far right, show the flash light output intensity (towards the right) and time (top to bottom).

The camera sends a series of commands to the flash’s microprocessor, as a digital (1s and 0s) signal. These settings tell the flash’s microprocessor what the desired power is and when appropriate instructing the flash to fire. The flash’s microprocessor converts these commands from power levels into how long it should leave let the flash fire.

When instructed to fire, the microprocessor’s changes the voltage on one of its low voltage signal lines, which in turn causes the IGBT to allow current to pass to the flash tube. When the desired amount of flash power has been emitted the microprocessor stops providing a signal to the IGBT which in turn stops allowing current to flow though the flash tube.

It is important to understand that in the scheme of things, neither the camera nor the PocketWizard has any direct control over the IGBT. The camera or PocketWizard can only tell the flash’s microprocessor what settings it needs, and when to trigger the flash.

In short, this means that it’s possible that these failures would have occurred even if PocketWizard’s never entered the equation.

Further, from my reading of the report, it appears to me that the problem with the failed/fired IGBTs is at least partially directly related to the flash tubes arcing to the reflector, which they shouldn’t be doing. This uncontrolled electrical arc can seriously alter the current levels the IGBT has to deal with or even propagate directly to the IGBT in a way it isn’t designed to deal with.

An electrical arc is like a miniature lightning bolt. Further, its ability to form is directly related to potential (voltage) between the surfaces that is forms between and how well that gap resists the formation (distance and conductivity). For example, an arc may from between two bare wires separated by air (as in a Jacob’s ladder) but insulate the wires and the arc will no longer form.

This brings me back to how a flash works, specifically that the voltage though the flash tube remains fixed and the timing is adjusted. In short, the PocketWizards can’t influence the voltage between the flash tube and the reflector, only the timing between when it turns on and off.

Moreover, it appears the gap between the flash tube and reflector is only at the threshold of spark formation, as, according to the report, it wasn’t seen in every test pulse, even if the power and discharge profile was kept the same. However, variations in alignment between the flash tube and reflector will change these characteristics and are specific to each flash made. Moreover, some flash designs, like the 430Ex II, have a much larger gap between the tube and reflector which makes it very difficult for the spark to form. This last part explains why some models of flashes are less susceptible to this failure than others.

The randomness of the spark means, the more the flash is fired the more likely it is for one that’s one that’s primed for failure to fail. This means, that using high-speed sync—one of the best reasons I’ve found for using the Control TL PocketWizard—raises the chances of failure due to the repeated firing of the flash over a single exposure resulting in more chances for arcing and thus frying the IGBT.

What this means for us as PocketWizard users

The real question to me is how do we, as PocketWizard users, move forward with this information.

My answer the first question, and while I can only speak for myself, is that I’m going to continue to use my Control TL PocketWizards. The potential failure seems to be directly related to the flash head (manufacturing and design tolerances) and not the PocketWizards.

I’ve had my two 580EX IIs in moderate use on my Control TL ‘Wizard’s for more than a year, and even longer using high-speed sync on camera. My feeling is if they were going to fail, they probably already would have; not that it would stop them from failing in the future. Further, since the PocketWizard’s high-speed sync mode isn’t driving the flashes any harder than a Canon EOS 40D would, and that’s what I used for most of their life, I’m not putting any more stress on them now, than I was before the PocketWizards.

That said; let me be clear about one thing, I don’t like the prospect of killing my rather expensive flashes. I’ve read LPA Design’s report, and while they’re the manufacture of PocketWizards, if you ask me, it’s in their best interest to fix any problems that exist or risk hurting the sales of their product. Moreover, their report is incurably detailed and technical to a point where I have a hard time believing they’re just trying to cover their own rears.

One thing to consider, if you are a Canon 580EX II user, who’s had their flash fail and is sending it off for repair, make sure the flash tube and reflector are inspected for damage and replaced if that is the case.

The LPA Design report can be downloaded from here and I’ve mirrored a copy here.



I have several 580EX II’s. They were purchased at different times, from different vendor’s. In fact, in different countries. I purchased PW FlexxTT5’s for my studio setup, that includes White Lightning strobes, and the 580 EX 2’s. AC9’s were purchased for the WL’s, and AC3 controller for the camera. I’m in deep.

I have used the 580 EX 2’s on and off camera extensively. Never a problem with flash performance. I set up the studio to do testing with the new PW’s. This included the 2 580’s connected to TT5’s and AC5’s. Both. Both were working for about 5-6 shots each. Within 10 shot’s both were exhibiting identical symptoms that I now know to be PW related.

How could 2 flash’s from different vendors, which worked flawlessly before, BOTH be ‘fried’ within a few shots of each other? The only new variable entered into this equation is PocketWizard. I could see how PW could hide behind the “you can’t prove it was us” theory is it were a single flash. But I refuse to believe that these 2 flash’s died together ‘coincidentally’. Now I have 2 expensive flash’s I can’t use. And $1500 of PocketWizard gear that I’m AFRAID to use, even when I get the flash’s repaired. Instead of behaving like this, PocketWizard should step up to the plate and do what’s right!

If it’s only .5 of their customers, what so they have to lose? TTL is coming out on many trigger brands thses days, We have choices, and with the whole AC5 catastrophe, do they want people to see them as an industry standard, or greedy corporate thugs? My entire studio format has had to change, but I lack the funds because it now sits in PocketWizard’s bank account. It isn’t acceptable, it’s their move to do something right.

The sad part is, the released the TT5, and it didn’t work properly with the 580 EX2, so they give us a jerry-rigged “fix” known as the AC5. So, I trust them, and now my speedlites are ruined. I jumped through their hoops because I trusted them.

For them to blame Canon, without any proof betrays their true intent, it’s selfish and careless. If this was common in the flash BEFORE the FlexTT5, then where are those complaint’s? There seem to be none. But now, even if there were, I know in my heart, the AC5/TT5 are culpable for my damaged flashes (and therefore PW). How could we all have EXACTLY the same damage? How could I get 2 flashes to damage at the same time?

Who can help me? Are they concerned at all? This is devastating for me.

V. J. Franke | admin

@ Russell,

Let me just say, I sympathize with your situation. All my Speedlites are 580Ex IIs and are therefore susceptible to this problem. It’s certainly not a reassuring feeling to know that your flashes could spontaneously die and your out more money to get them fixed. Let alone die on a job when you actually need them.

I would also like to reiterate the advice given in the article. If you send the flashes back to Canon to have them repaired, insist that the flash tube and reflector assemblies are inspected for burns and arcing, or simply outright replaced. If they aren’t then the issue will reoccur in short order, regardless of whether you use the flash on a TT5, Canon camera, or any other triggering method.

As to your specific situation, so far as I’ve been able to determine, the problem is not endemic to a specif production run or production line but rather the product itself. Unfortunately that means that, spreading your purchases out won’t reduce the probability of getting defective flashes.

Further, I think it’s pretty clear that PocketWizard is neither hiding or proffering baseless theories about this. The problem, data supporting it, and images of the damaged flashes are all contained in the linked report. For that matter they’ve been more forthcoming about what the problem is and how they’ve diagnosed it than any other camera, or camera related, company I can think of.

I’ve tried to clarify the problem in my article, and the LPA Design report goes into considerably more detail. If you have specific questions about something in the article or report that you don’t understand, I’d be more than happy to try and explain it, if I can, in the comments here.

In any event, I would encourage you to contact LPA Design/Pocket wizard either by email or phone and report your issue. I’m not sure if they can offer you any help; I don’t speak for them, but they may be interested in whatever data they can get about your specific case. In addition, I would reiterate what I said above if you choose to get the flashes repaired, make sure the flash tube and reflector assembly is inspected and replaced if there are signs of arcing.

I’m sorry that you’ve had problems with your TT5s and 580Ex IIs, it really sucks and no amount of rationalization or explaining is going to make you any less frustrated or disappointed.


Hi, thanks for your advice. Unfortunately, my problems is not about getting a defective flash. It’s about getting 2 in the same go. Now, if that can be ignored, then I suppose any thing can be. The point of mentioning my flash’s were purchased at different vendors it’s to stress that they aren’t from the same production run, whether that be a factor, or not. But if we are to address this problem SERIOUSLY, then we can’t just overlook facts. How can two Canon lights go out at the same time, with the same symptoms, and it be Canon’s fault? I tried to be meticulous in my previous post so that my experience could help shed light on this problem. It’s all over the internet, and it is always 580 EX2’s and AC5’s + FlexTTL’s.

Again, because I was able to pin down the exact time these two flash’s went out, just moments after adding the AC5, it allows us to observe, photo by photo, the sequence of events. I’m unable to think of a single scenario where two flash unit’s from two different vendors can go out simultaneously, and it be a default with the flash. That is insanely to much coincidence. No, you take that coincidence and throw in all the complaints ton the internet that match my situation. I’m sorry, but if PocketWizard hasn’t stepped up to do the right thing, then they are effectively spitting in the faces of those who supported them. And again, if it’s such a small percentage, then why not eliminate suspicion? Why not instill confidence?

I appreciate your reply, and especially your advice on repairing the units, but unless you take these points to heart, companies will continue to behave in this manner. Unless you consider all the facts that I have mentioned here, then it will be misinformation that is spread. I have no idea if there are vested interests, and I suppose it doesn’t matter, but how does their research explain my situation with the 2 flashes lost at the same time? Coincidence? Unexplained phenomenon? The fact that so many incidents are documented rules out any silly things like that. So many, that PW had to address the problem. Come on now, why should we look so hard for a difficult answer, when the obvious one is in plain sight? Occams razor, and all, ya know? I will follow your advice on the flash repairs, thank you kindly for the details.

    V. J. Franke | admin


    Re: using the AC5s, that does raise a question in my mind, did the flashes work fine on the TT5s Prior to using the AC5s or did you not use them that way?

    I’ll be honest with you, I don’t care for the AC5s, and I don’t use them unless I absolutely have to and even then I cringe a bit. So much so that I’ve been considering buying AC7s, getting a couple more OC-E3 (or cheap knockoffs) off camera cords, or having my flashes filter modded (my preference) to avoid the issue completely.

    I took an AC5’s hotshoe filter apart back when I first heard someone complain they thought their AC5 killed their flash. They are ingenious, but I have my concerns that there isn’t the potential to short out the communication pins, never mind there’s the copper plane the shield mates with is a nice big unimpeded path to ground that’s exposed to the world.

    Unfortunatley, given the limited electronic testing resources I have, other than verifying that the pins weren’t shorting out to any other pins, I can’t actually test them in a meaningful way.

    Also, as much as it may pain you, I think you really need to start a dialog with PocketWizard about this. Just because they’ve identified a problem with some Canon’s flashes that they feel isn’t related to their TT5 triggers, doesn’t mean that there isn’t a problem with the AC5, the interaction of the whole system, that your TT5s (one or multiple) could be defective or out of spec, or that it’s not something external (like static discharge thought the metallic cloth into hotshoe filter).

    I honestly hope you get your flashes sorted out and working. Unfortunately, like I said, I have no association with PocketWizard, so I can’t even offer a push in the right direction or light a fire under someone to get things rolling for you.

    Also, if you do find out anything from PocketWizard or when you get this whole mess resolved, I would appreciate it if you could drop a line back here letting me know how things turned out.


I think the remote cord is a simple, brilliant suggestion. How strange to find brilliance in our regression! But it’s true. The plus side of this whole ordeal, is that I’ve gone back to manually lighting, and it’s helped me improve.

Yes, I did use the FlexTT5 a few times before, and it was having reliability issues, which led to the AC5’s. I’ve had several enlightening discussions with my wife, she being the voice of reason in our family. It basically comes down to changing the flash model or changing the trigger brand. The AC7’s is just another cumbersome ‘fix’ that mean’s giving more money to PW, and since I do 50%+ of my shoots in the field (sometimes literally in ‘fields’) The AC7 is even less attractive of an idea than its use in the studio.

So, keeping the FlexTT5’s and going with 430EX2’s might be my choice. I was looking over the new Phottix Odin triggers E-TTL triggers, but honestly, it’s just not worth the expense. It would cost more to change trigger brands than to buy a few 430EX2’s. And, Having 2 set’s of triggers is no better than having 1, it’s a step backward, because I will spend the money, and still will only have ‘more’ triggers to show for it. But having a few more flash’s appeals to me as a step forward. To PW credit, the AC9’s and the AC3 have redeeming value. I’ve learned my lesson, and it will cost me, but it’s ok, I’ve accepted it.

As for PocketWizard, I’m presently in talks with them. I live in the middle east, so it’s a big problem conducting any investigation from here. I miss the states anyway, but it’s times like this that I truly miss home.

As for the testing of the AC5, I’m not sure where to start, however, I don’t believe the FlexTT5 is the culprit. Stating the obvious, the metal component of the sock is where I’d place my bets, but I have no idea how to test that without risk of damage to the electronics involved.

I know that you aren’t associated with PW, that’s why I chose to vent here! I appreciate your point of view. I really do. And you know, I feel much better. Communication has helped me organize the situation, in my mind. It’s in a clearer perspective, and it’s easier to see past this problem. It will have to be resolved, but we were taking photograph’s long before wireless triggers came along…no reason to not move forward.

I have a set of Yongnuo Chinese triggers (RF-602’s) that I’ve been using for years. They aren’t TTL triggers, but they are as reliable as any other equipment I own, Canon & PW included. I’ve used them in more situations that I can list, and never leave home without them, even when PW’s are being used. A set of four receivers and 2 transmitters cost me less than $80. They are tiny, lightweight, and reliable. I will just use these for now, along with some older flashes I have.

Since it will be manual anyway, I’ve pulled out my old Vivitar flashes, another reliable brand. Those flashes have been to Hades and back, and still fire every time. The do just fine for hair lights and separation lights… and background lighting too.

Hope Yongnuo offers up an E-TTL wireless trigger someday, as they already make E-TTL Flashes. I read recently that they updated the RF-602 triggers to be transceivers (RF-603’s) A set of four cost $61.50. Not bad, but what floors me is that my faith in a cheap Chinese trigger is leaps and bounds ahead of that for PW.

Thanks VJ, I’ll certainly share updates, good or not-so-good.

    V. J. Franke | admin

    Actually I found that page really useful, for the link on tightening the flash shoe, go figure. Diagnosed and fixed my one wobbly 580ex II that I never even realized was wobbly.

Our cookie and privacy policy. Dismiss