View Full Version : Compur Electronic 1 - stuck in T mode?

5-Apr-2017, 13:31
Hello, I have in front of me a Compur Electronic shutter - which is a shutter I know nothing about! It seems (to me) stuck in T mode, i.e with the shutter time scale set to T, it functions as it should, operating the black release lever opens the shutter, operating it again closes it... The small red flag next to the T is up - which I assume indicates that the shutter is in T mode. When I turn the shutter time selection ring to any of the other times (which is freely possible) the red flag does stay up, the shutter still opens when the release lever is pressed, but stays open, until the cocking lever is spanned, which closes the shutter. There is no difference to this behaviour between running the shutter with or without 4.5V supply connected.

So, is this shutter likely toast, or is there a procedure to take it out of T mode to operate it timed? Thank you for any advise!

Bob Salomon
5-Apr-2017, 13:35
Are the batteries good?

5-Apr-2017, 13:46
I'm running it off a regulated supply at the moment, just to exclude batteries and the contact pins as a potential issue.

5-Apr-2017, 13:48
P.S.: Thank you for the quick reply Bob!

5-Apr-2017, 13:51
...what would be the normal procedure to take these out of T-mode? Just turn the timing ring to a fixed speed setting, and the red flag should disappear?

5-Apr-2017, 15:55
I don't know about Compur 1 Electronic shutters, but the red flag on Copal 3 shutters goes up to indicate that the lens is cocked. It goes down when the shutter is fired. I have a Copal Elec - No. 1 shutter, but no batteries. That shutter doesn't have a T setting, and when no power is supplied, it fires at a fixed speed probably 1/250th or 1/400th.


Paul Ewins
5-Apr-2017, 23:24
The Compur Electronic shutters are an electronically timed mechanical shutter. With no power the shutter should fire at its fastest speed. If it is behaving as if it is set to T regardless of the speed selected then it sounds like a mechanical issue rather than an electronic one. All I can think of is that the shutter speed selector ring is not connected. When I checked one of my own Compur Electronic shutters I found that I could use the T setting regardless of whether the shutter was cocked. If it was cocked, however, then it stayed cocked while on the T setting when I used the release lever to open and close the shutter manually. If I then turned it to another speed it would fire normally. So it sounds like you shutter is cocked, but stuck at the T setting internally.

6-Apr-2017, 00:18
So based on what I learned here, I can imagine two different problems. The red flag never fully disappears, and I imagine this will be controlled mechanically... So either the shutter is stuck in T mode somehow - which sounds like a mechanical problem. Or, maybe more likely, there is something wrong with the part of the mechanism or control circuit which is responsible for closing the shutter in fixed time mode - so when set to fixed time, the shutter simply never closes until it gets re-cocked - which seems the case, since with fixed times only recocking the shutter will close it. So that still sounds more likely to be mechanical I imagine, though less sure. Looks like I have to open it up, which I can't say I'm looking forward to...

18-Apr-2017, 14:17
Just thought I should post a final comment, in case anyone comes across this thread in a search for a similar problem. I opened up the shutter, and it was indeed a mechanical issue: inside the shutter, the lip from the shutter release lever which is meant to get pushed down by a remote cable release had broken off, and got stuck under the spring drum which in fixed time mode opens and then closes the shutter. This still allowed the shutter to open but prevented it from closing, when set to fixed times. It was in fact quite easy to 'fix', and I didn't find the inside of the Compur Electronic as daunting as I expected - at least the mechanical side seems pretty straight-forward. So I now have a shutter which is working, both in T mode and with fixed timings - although with the little lip inside missing, unfortunately it can't be triggered by cable release.

18-Apr-2017, 14:20
...and just to confirm, yes as with other shutters, the red flag simply indicates that the shutter is cogged - as Kumar suggested.