Sunday, February 5, 2012

Cullmann D4500-C fail and teardown

 This story is about one of my definitely worst experiences at eBay.
Recently bought a Cullmann D4500 photo flash in order to have a second flash (in addition to the Canon Speedlite 580EX II) for lightbox photography. That didn't require a very high quality item, and the D4500 seemed suitable for the task. In addition to spend some light, it has focusing capability, a built-in wide angle bouncer and - which was important for my use - could be used as a slave flash unit. Didn't want to use cables anyway. The market price for this unit was around 180 EUR, but it is no longer manufactured. I placed my bid at 80 EUR successfully.
I chose the "C" model that is said to be compatible to Canon DSLRs and also capable of managing E-TTL.

Bought from a private seller which taught me a lot again. In Germany, you have to exclude warranty and return explicitly, which you can do only as a private seller. If you don't, civil law makes you responsible to almost a professional-seller level. In this case, I did not see any such statement which reassured me a little that in case something is wrong, I could use this against the seller.

The flash was said to have been stored unused for almost 2 years because the seller has changed to Nikon.
In the eBay item, nothing seemed wrong, it was advertised as being in a perfect and rarely-used condition. As it arrived here, everything seemed okay, not much wear and tear, and I wanted to give it a try on rechargeable batteries which worked perfectly in the Speedlite. 1.2V at 2650mAh, fully loaded.
Powering up the unit, I could hear the focusing motor working with a rather low and inconstant noise, and the rising frequency of the charging circuitry could also be heard pretty well (in extreme contrast to the Canon Speedlite that is instantly ready to fire and does not make a sound at all). The READY LED (that is the TEST button at the same time) would light up, but pushing it would not do anything. The high whistling sound would stay audible and not change its frequency any longer, suggesting that the charging had finished. Nonetheless, no light.
Then I thought the rechargeable batteries which deliver 1.2V might deliver too weak a voltage for the unit to work properly. I chose a set of fresh Alkaline 1.5V batteries instead. The power-up sound was much louder and the focusing went considerably quicker. Plus: the unit fired properly! WOW. But in contrast to the manufacturer's data, it took a whole lot longer than 9 seconds to recharge for the next flash. I waited for about a minute, then testing again. Another flash. Okay, I could live with that. Lightbox photography requires a lot of manual arrangement anyway, I would not have to take 10 photos every minute. So I waited again and pushed the TEST button from time to time to find out how long it actually takes for it to recharge.
The next event was about 20 seconds after the last flash, but no light was involved. Instead, the whole unit went BANG in my hand, then recharged! I switched it off as fast as I could. No damage was visible so far, and also no smoke, but a strange smell came from the unit ever since.
I removed the batteries and found they had become pretty warm, actually much too warm for a normal operation. Seems they have been on heavy duty in there. My battery tester told me they were only 70% of normal voltage already! After only two flashes and one explosion!
So now it was clear something was very very wrong about the damn thing. Later attempts of getting it to work all failed. It would behave like it did in the very beginning, focusing, giving the charging noise but never firing.
I had no success of getting to terms with the seller. He refused to accept that the unit was broken and I would return it, mentioning that he had excluded this explicitly which to this date I did not find in the eBay offer description. Later it became clear why I had not seen it. He hid this bit of information on the "delivery and payment conditions" page in a field that is reserved for a different purpose. This info is a separate "tab" on the eBay page and you have to click it first.
Either way he insisted on having sold a good unit and not accepting any of my complaints and offers to return it to him at no cost.
Another explosion happened a few days later when I gave it another try. As it was clear now that neither I would get my money back and get rid of this trash, nor would I be able to use it for my own photography, I decided to look inside to find out what has broken.
Maybe I had too high quality expectations for a device around 180 EUR. On the outside, I'd say the flash is mediocre. Nothing terribly wrong but the LCD display alread made a very cheap impression. It is one of these models where the dark segments of the LCD are half-transparent and very near to the front side of the glass, and they cast a shadow on the back of the display. That does not look so nice if the light is falling in from the side. The backlight is a bad joke. A weak green glow that only lights up the left half of the display at all, and again, due to the segments being anything but a clear black, it would not help much in recognizing anything on the display.

The buttons are made of rubber, actually it is one of these rubber "mats" as known from remote controls. They are rather small, and give no feedback at all, so you never know if pressing one of them was successful or not. Maybe that is the reason why a buzzer was integrated that would confirm every button pressed (at least after it is turned on with one of the rubber buttons).
The unit would forget all settings once it is powered off. Another dubious thing, but well, maybe normal at the price tag.
So, let's get inside. A lot of screws have to be removed first:

4 at the bottom

2 at the top right
another 2 at the top left

Now the first peek inside:

Ugh... that's not a nice scene. Colored wires all over the place linking multiple PCBs on which they are directly soldered. No pluggable connectors at all! How should this ever be serviced??
The lower part of the unit seems to contain most of the control logic, but nothing about high voltage, so the interesting part would probably be in the head of the unit.
The head link to the body is loose already after opening the lower unit. On the bottom side of the head, there is another set of screws:

Beneath the plate seen in the picture above:

Still would not open. Ah, more screws beneath the side covers, again four per side:

The first look reveals the mechanics to lock the flash head vertically:

And we're in:

Hmm, so finally we are reaching the high voltage parts. There is a coil (blue), the capacitor must be hidden in the cylinder on top.
Some screws later, here it is. The smell obviously comes from here, too:

Mind the dent:

So probably this is the part that was blown up.

Good thing that it was covered at least by some plastic around it. God knows how far the explosion would have gone otherwise. Okay, more about this later. Let's take a view at the focusing mechanics:

Well, surely not highest quality, too. There is a very small conventional motor that drives the white spindle that you can see in the middle of the picture to move the flash bulb / reflector unit forwards and backwards. The lower PCB is to locate the position of the reflector, there are two parallel PCB lanes, one being the "ground" line and the other being subdivided into five stops. A contact between them is made by the metal slider that is attached to the moving part (see right below the flash tube's right end). This is where the motor controller gets to know where to move and when to stop.

I'll now take a look at the PCBs and eventually dismantle the capacitor to find out what has happened.

display / button PCB - this is actually the backlight unit, the LCD panel was removed

display PCB - mind the wires being "surface mounted" - what a mess! Often, the wire insulation would be cut away far from the soldering point, giving some chance for shortcuts.

backside of the display PCB - these "blob"-style ICs seem typical for cheap devices

bottom PCB. This is where the camera connector is attached (colored wires go to the unit's foot)
bottom PCB from another angle
high voltage PCB bottom view - this is the bottom PCB in the head unit. All wires from the lower unit arrive here
high voltage PCB top view - mind the badly arranged components. Not much in line there!
high voltage PCB rotated 180°
high voltage PCB side view. Component alignment is as bad as it can be
choke... this is the unit's bottom PCB again, with another unknown IC uncovered

The only thing I liked about the layout is the silk screen that indicates what most of the connections do.
Now for the capacitor, it's a photo flash specific build with 1000µF and 330WV. Pretty "capable" indeed. Here's the clothing:

And the capacitor without it. That dent is actually there, it's not bad optics or something! The blow took place right underneath:

Opening it is dangerous for your fingers in multiple ways! First the metal cup has pretty sharp edges once you pry the bottom neck open:

And then the electrolytic stuff in there sure isn't healthy. Better use gloves (unlike I did) or try to not touch it at all. Especially the more powerful capacitors are probably made of more powerful chemistry. Excuse my bad example here, touching everything with bare hands. Do not try at home!

Interestingly, there are more than two connections inside, actually two per polarity, going to different segments of the capacitor.
This is it, seen from the side where the dent was in the cup:

A capacitor is actually a wrapped long strip of metal sheet and a long strip of paper or plastic foil, so let's dig deeper. The explosion sure didn't take place on the surface, otherwise there would be burn marks or stuff. The first round unwrapped shows that there is actually a small hole going through all layers:

The hole becomes a crack one revolution deeper:

Then becoming a hole again:

It does not seem to stop!

Well okay, one meter or so inside the cap, and with not much wrapped up anymore, we find the center of the blowout:

Seen from the other ("paper") side. Does not smell to good. Let's get rid of it.

Hard to say if this was just a faulty component, or the explosion was caused by a voltage too high or the cap being overcharged by the device electronics. I might have fixed the problem by replacing only this capacitor, but a replacement part would have been pretty costly (around 35 EUR), and might not have fit exactly into the case. Moreover, the anti-service construction spoiled it. Lots of metal springs, small metal plates, contacts etc. fell right out during disassembly. No idea where they'd belong so I'd never have been able to put everything in its right place again. That wired nightmare is definitely not built to be repaired.
So that's it. The piece of trash, trashed:

In summary, the unit may be worth its money after all if you can live with the bad internal design. Maybe the capacitor was blown out before, and just exploded two more times when I had it here. I cannot prove it. Maybe the manufacturer did everything right and the thing was stored inappropriately. No idea, anyway, it didn't live long as it seems, and did not really live up to its purpose.
Eventually, I have dug the internet for more info and experience reports for this model, not finding much, and what I found was not positive mostly.
For instance, even if this had worked perfectly from a technical point of view, using it as a slave unit would still have failed because E-TTL II uses control flashes for the camera and flash units to communicate before the actual flash goes off along with the picture taking. But the D4500 would fire along with the very first flash, no matter if it is a control flash or the real deal. That would have spoiled it for sure because the D4500 would always flash too soon.
I have also contacted the Cullmann support to find out if they know about this issue. Actually that was before I decided to dismount it but it took so long for them to answer that I didn't anticipate any answer at all.
What they told me is expectedly disappointing: that I probably have bought a defective unit (aha) and that it is not compatible to the Canon EOS 7D unless it is less than two years old. Not offering any real support for my case, no repair instructions, service addresses, or anything else. Okay, again, why expect more after seeing all of this? The unit is cheap, and it is made cheap, and I'm sure they had to repair at least 50% of their units sometime if they are all of this quality. It seems only logical that support is also kind of cheap.
Another bad experience about all this: the missing manual. In contradiction to what the eBay item description stated, there was none delivered with the unit. Eventually I found one with Google's help, but it fails to explain what the F/STOP button does. Actually I had no chance to find out before it failed.

Lesson learned: bought a Canon Speedlite 430EX II now instead, and that's a different world in comparison. In the future, I'd rather buy the quality product right away even if it is three times more expensive. At least that gives you the chance to get something that meets your expectations.
Forget about Cullmann. Interestingly, they only sell camera tripods and tripod accessories today, no more electronics. I think that was a wise choice.


  1. thank you,
    with the help of this post i just repaired my flash (different problem)

  2. Hi Johannes. Do you still have the remainings of this flash? I'm have one fully functional but the mounting shoe is broken... Best regards. Sergio

    1. Dear Sérgio, I am sorry, all the parts were discarded a long time ago. Let me tell you, the original Canon SpeedLite 430 is so much better, and still pretty affordable, you might consider getting one of these. It's a different universe, really. You won't regret it.


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