Compur electronic #1 acting strange?

[koh303]

I know this is a long shot, but perhaps someone has had this experience and can help out?

I have a compur electronic #1 shutter.
Installed fresh battery but the shutter does not fire consistently. It will fire once or twice at the set speed, and then will not fire again. If i wait a few minuted, i will get one or two more correct shots, no matter what the setting, then nothing.

Any ideas?

[Paul Ewins]

I don't have a diagnosis, but perhaps can spark some ideas. The 0,1 & 3 electronics all work the same basic way. The shutter fires at the same speed every time (the highest) but there is an electronically timed delay between the shutter opening and closing. i.e. 1/500 = 1/500 + no delay, 1/250 = 1/500 + 1/500 delay, 1/125 = 1/500 + 3/500 delay and so on. The delay is regulated by resistance. This is achieved by a semi-circular circuit board with a range of resistors mounted on it. As you move the speed selection lever around it moves from one resistor to the next. If it was just one speed or range of speeds not working then I would look at the resistors. Since it is an intermittent fault it could be that the solenoid that holds the shutter open (i.e. delays the closing) is somehow faulty and is sticking open. If it wasn't working at all then I would expect it to fire at the highest speed only, which is what happens if you don't have a battery.

[Old-N-Feeble]

Paul may be right but I'd suspect a faulty capacitor or dirty/worn switch.

[EdSawyer]

Don't these also use a capacitor, that requires a charge-up time from the battery? If so, that could explain why it gets consistent exposures when given time to charge up. Also, if it uses the rare 4.5v battery like a Compur 3 electronic, chances are it's not really *fresh*. Those sit on shelves for ever since no one buys them. Try wiring up 3 1.5v cells in series and see if it fires better with that. Actually any battery in the 3-6v range should work fine, these are often run off CR23s and the like. (smaller, cheaper, easier to find, work just as well, etc.)

[Old-N-Feeble]

If you try a battery of slightly higher voltage just make sure the circuitry can handle it. Specifically, capacitors may pop or leak if subjected to voltages higher than their ratings. And, Ed's right too... you may have a weak battery.

[koh303]

I don't have a diagnosis, but perhaps can spark some ideas. The 0,1 & 3 electronics all work the same basic way. The shutter fires at the same speed every time (the highest) but there is an electronically timed delay between the shutter opening and closing. i.e. 1/500 = 1/500 + no delay, 1/250 = 1/500 + 1/500 delay, 1/125 = 1/500 + 3/500 delay and so on. The delay is regulated by resistance. This is achieved by a semi-circular circuit board with a range of resistors mounted on it. As you move the speed selection lever around it moves from one resistor to the next. If it was just one speed or range of speeds not working then I would look at the resistors. Since it is an intermittent fault it could be that the solenoid that holds the shutter open (i.e. delays the closing) is somehow faulty and is sticking open. If it wasn't working at all then I would expect it to fire at the highest speed only, which is what happens if you don't have a battery.

Thats all true, however, i did neglect to mention that when the shutter does not work properly it does not fire at all. I can hear the mechanical release and the solenoid clicking but the shutter remains closed.
What should i clean the solenoid with? It is tiny, and not easy to get at without splashing or breaking anything else (including many tiny solders running along on either side, completely unprotected...)

[Old-N-Feeble]

A weak capacitor or battery can do that.

[Stanislav Briza]

Hello, I´ve just got nice xenotar 135/3.5 however mounted in Compur Electronic 1 shutter... I did some research and generally it seems to be a bit pain in the ass this shutter. Anyway, I cleaned the pins from corrosion and connected two CR2032 3V Cell batteries. Shutter seems to work with times longer than 1s but anything faster up to 1/500 fires at default 1/500. I reckon something is wrong inside, does anybody know what to check next? Or is there any tutorial, video or so? Thanks!

[Jeff Keller]

I don't know anything about the Compur Electronic shutter but many photographic items used mercury batteries because they kept a very steady voltage. Neither 1.5v alkaline batteries nor rechargeable batteries have the same voltage. Production of mercury batteries stopped years ago because of the toxicity.

Good luck sorting out the issues.

[Stanislav Briza]

Thanks for advice, I fixed it yesterday. I sprayed WD-40 contact spray inside which was like a miracle - short times started to work! After I soldered two LR44 bateries, secured it with hot glue and put it in my graflex. It fits perfectly.
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