8x11 Flash with Minox EC - Need help

[tjwspm]

I have the following problem:
I mounted the Minox 8x11 flash on my Minox EC. Then I turn on the flash and hear the high-pitched buzzing sound as the flash charges. Then the following happens: As soon as the flash is charged, it fires immediately. I don't press the shutter button.
That's not what I expect. After the flash fired automatically, it recharges and immediately fires again.
This happens regardless of whether I set the camera's switch to "A" or "Flash". It doesn't matter whether the shutter is cocked or not.

What could be the reason?

I just bought the Minox EC as new and unused. Here's how I tested the camera:
- The battery test works.
- The automatic exposure mode works perfectly.
- If I set the switch to "Flash" but don't connect a flash, after cocking and releasing the camera the shutter opens briefly (it could be around 1/30 s)
- When I use the Minox FE-4 flash adapter and a flash cube, everything works perfectly: the flash fires when I press the shutter button

I bought the Minox 8x11 flash separately from the Minox EC and tested it as follows:
- I connect the 8x11 flash to a Minox A IIIs with the adapter
- When I press the shutter button on the Minox A, the flash fires as expected

Who can tell me why it doesn't work in the combination Minox EC with Minox 8x11 Flash?

 

[Chan Tran]

What if you don't mount it on the camera what happens? If it doesn't fire as soon as it's ready wihout the camera then the camera sync contact is shorted or because you mount it somehow not correctly and cause a short.

 

[tjwspm]

Thanks for your questions.

If I don't mount the flash and turn it on, it charges and the lamp lights up. Otherwise nothing happens.
If the camera sync contact is shorted, why does it work with the Minox FE-4?

Maybe I actually mounted the flash incorrectly, but how could I find out? Are there any other tests I could do?

 

[xkaes]

I'm probably wrong, but I thought the EC had a flash that was specific to it.

 

[tjwspm]

You're right, the Minox 8x11 flash was designed by Minox specifically for the Minox EC.
That's why it's so strange that the flash works with my Minox A, but not with the EC.

 

[xkaes]

As I recall, the EC flash has a unique three prong connection, and the Minox A (AKA, Minox II) does not even have flash synch.

 

[tjwspm]

As I recall, the EC flash has a unique three prong connection, and the Minox A (AKA, Minox II) does not even have flash synch.

Yes, but there is an adapter for Minox A IIIs,

https://juliantanase.com/wp-content/uploads/2022/12/DSC_3503.jpg

described here:

Minox 8x11 flash - Julian Tanase Photography

Minox designed a small electronic flash to accompany the small Minox EC camera. Small enough to go into the palm of your hand with room to spare, it is powered ...

juliantanase.com

 

[xkaes]

OK, my misunderstanding. You have a IIIs (1955-1969) not an A / II (1948-1955).

The fact that the flash works with your IIIs indicates the flash is OK. So I suspect the contact on your EC.

 

[tjwspm]

So I suspect the contact on your EC.

The question remains why the FE-4 adapter with flash cube works perfectly with this Minox EC.

One answer could be that the FE-4 gets the power for the flash cube from the camera battery. The middle of the three contacts is connected to the negative pole of the battery. Perhaps with the FE-4 only the middle and one of the two outer contacts are used, while with the 8x11 flash with its own battery perhaps only the two outer contacts are used, which it only uses as a switch.

I'm not very familiar with electronics, but maybe this explains why the camera can handle one flash but not the other, right?

 

[xkaes]

Could be. Too bad you don't have another EC to test with it.

 

[G1DRP]

When using the cube flash, the EC supplies the camera’s battery voltage to a filament, in the cube, which lights and ignites the magnesium wire. I assume that when using the electronic flash, it shorts two of the contacts. I’ll have to look into this as I’m quite curious about this myself.
Anyway, the EC is an incredibly useful camera and I obtain stunningly sharp photos using ADOX HR-50.

 

[tjwspm]

When using the cube flash, the EC supplies the camera’s battery voltage to a filament, in the cube, which lights and ignites the magnesium wire. I assume that when using the electronic flash, it shorts two of the contacts.

Since the contacts are easily accessible via the battery compartment, I took measurements. The two outer contacts have a resistance of approx. 10KOhm to each other. I would have expected them to be completely separate from each other.

 

[tjwspm]

Anyway, the EC is an incredibly useful camera and I obtain stunningly sharp photos using ADOX HR-50.

Indeed. I can't see any differences in picture quality to the other Minox models. Minox EC with CineStill 50d:

 

[tjwspm]

Success! The mystery has been solved.

There was a short circuit between the flash contacts due to corrosion.

Here's what I did:
- all three cables desoldered (blue cable: battery ground, grey and black: flash contacts)
- the contact plates and the insulation removed from the housing
- Contact plates, insulation and housing carefully cleaned
- everything was reassembled and glued together (unfortunately these parts were not screwed, but fused to the housing with plastic pins)

The short circuit was not visible. Not even after removing the parts. The cables were undamaged.
The cables were extremely difficult to solder. Not just because of the narrow space. I had to sand the cables and contacts; flux alone wasn't enough.

I bought the camera as unused with the information that the battery had never been inserted. The battery compartment was completely clean. Nevertheless, the short circuit occurred.

Now the 8x11 flash works as it should:

 

[xkaes]

Job well done. Congratulations!

Now if we could only get that flash to be smaller!!!!

 

[koraks]

The cables were extremely difficult to solder. Not just because of the narrow space. I had to sand the cables and contacts; flux alone wasn't enough.

Yes, that's normal. Corrosion will build over time on copper wires. This needs to be removed and flux by itself often doesn't get the job done.

Btw, you might want to check this contact:

That's not a good solder joint; you may run into trouble with it in due course. Even if it works now, as soon as mechanical stress (vibrations of normal use) and corrosion get to it, you might be in trouble. It may not be noticeable if you use a flash unit that only relies on grey & black being shorted. If the battery negative/blue wire is used to ignite a flash cube, then this will definitely be a problem since the current carrying capacity of the connection is more important than with just a trigger contact.

 

[tjwspm]

Now if we could only get that flash to be smaller!!!!

That's true, though. The flash is bigger and heavier than the camera. However, I don't know of any smaller external flash than this one.

 

[tjwspm]

Yes, that's normal. Corrosion will build over time on copper wires. This needs to be removed and flux by itself often doesn't get the job done.

Btw, you might want to check this contact:
View attachment 364777
That's not a good solder joint; you may run into trouble with it in due course. Even if it works now, as soon as mechanical stress (vibrations of normal use) and corrosion get to it, you might be in trouble. It may not be noticeable if you use a flash unit that only relies on grey & black being shorted. If the battery negative/blue wire is used to ignite a flash cube, then this will definitely be a problem since the current carrying capacity of the connection is more important than with just a trigger contact.

Thank you very much for the tip! Can you give me a hint as to how you can tell that this solder joint is not ok?
I have now taken a larger photo of the contact:

The blue cable is the most important of the three, as it supplies the negative terminal of the battery to the camera. If this contact comes loose, the entire camera will stop working.

 

[xkaes]

That's true, though. The flash is bigger and heavier than the camera. However, I don't know of any smaller external flash than this one.

I know of several, but they won't work with the Minox EC because of the unique connection. My guess is the smallest goes to the LOMOMATIC. It's so small it makes me wonder how much power it has!

 

[koraks]

Can you give me a hint as to how you can tell that this solder joint is not ok?

Yes, there are two hints in this case.
Firstly, the blob of solder is matte instead of nice and shiny. A good solder joint usually has a perfectly shiny, smooth surface.
Secondly, the solder doesn't creep up against the wire, but forms a cavity around it. This shows that the wire wasn't properly wetted with solder (it probably had some corrosion left on it).

The solder I use the most is a rosin-core solder and depending on the task, I may use additional flux. Moreover, in repairs like these, I would generally cut off the corroded end of the wire and strip a fresh bit. If the wire/cable is too short, I'd usually replace it - or try the best job I can do with the cable that's there, but ensure proper wetting of the stripped end.

 

[tjwspm]

Moreover, in repairs like these, I would generally cut off the corroded end of the wire and strip a fresh bit. If the wire/cable is too short, I'd usually replace it - or try the best job I can do with the cable that's there, but ensure proper wetting of the stripped end.

Thanks. I will cut off the end of the cable and re-solder this contact. BTW this was the only one of the three cables where I didn't do that. Later I'll show another photo of it...

 

[koraks]

Yes, the other ones look fine! I noticed.

 

[tjwspm]

Yes, the other ones look fine! I noticed.

Now I have redone the middle soldering point. Is it okay like that?

 

[koraks]

Yes, that'll work - and reliably, too! Well done.

 

[tjwspm]

Thank you! Your advice probably saved me trouble later.