Canon A1 Shutter Speed Problem

[HarrietteD]

Hi,
I have recently acquired a Canon A-1 and it seems to have shutter curtain problem. From what I can see when I open the back, the curtain moves when you wind the film on and when you press the shutter it looks like it moves incredibly fast (I think probably 1/1000) but when you change the shutter speed on the Tv dial, the length of time the shutter curtain opens does not change and neither does the time that the mirror is up. It seems like the camera is stuck on 1/1000 sec, the same happens when you change to P, B or Av mode or when you switch to L and back again. I am increasingly thinking that it is an electrical problem, but I am not knowledgeable enough with it to know if this is the case.
Can anyone help me out?

 

[gone]

I assume you have a new battery in there (or at least one that is a full 6V) and that the contacts are clean? If that part is OK, then you may wish to try the fix described in the link below.

http://www.rangefinderforum.com/classics/forum/messages/2/25969.html?1355583245

 

[HarrietteD]

I have put in a new battery, the contacts are clean too and I've just had a go at the fix in the link you posted but I've had no luck. There doesn't seem to be anything coming off mg3 when I gave it a gentle clean.

 

[David Lyga]

You know, HarrietteD, I think I am a bearer of bad news. There is a shutter timer that, I think, is a chip. I have sometimes seen this problem when testing a camera at a trade show and it is not always with Canon. I cannot see how the battery has anything to do with it, as it does fire. I assume that the red diodes light up as expected? Did you try both manual and auto (and Program?). The same results? When you fire the shutter, have the back open and point the camera at a bright area. Then fire as you look closely at the film gate. Do you see a fleeting whiteness, indicative of that 1000th shutter speed? If so, somehow that chip is locked onto that speed. No solution from me but I have seen this before. - David Lyga

 

[zanxion72]

The odds are that the shutter speed oscillator is done! Check first to see if while changing shutter speeds in Tv mode you can see the readout in the viewfinder change accordingly. If not then the good news is that the dial on the top of the camera needs to be fixed. This one is cheap and easy. If not, then you need to replace the circuitry on top of the camera. This one is an expensive fix and buying another A-1, even partially working is the only source of spare parts.

 

[Xmas]

Well normally it is a sticky seloniod ie electro magnet can of silicone rubber treatment spray few cc into aerosol cap and drip on to electro magnet with darning needle.

Keep dripping contain any escape with qtip.

Repeat you are trying to dissolve gum...

You would be well unlucky if it is integrated circuit but Id not spray directly on to camera risk of static shock and mobility of old lubricant...

If the camera works, stop while ahead.

 

[HarrietteD]

Hi David, I've tried it on both manual and settings and its always the same. When you look through the back and point the camera at something bright you don't see any whiteness at all, a curtain (presumably the second) comes across when the shutter is fired and cocks back when you wind on. Could it be that the first curtain is somehow stuck? The mirror moves up and down fine and I know that that is supposed to trigger the first curtain, but maybe something is wrong there?

Actually, scratch that. It looks like both of the curtains are being triggered together, so they both come across at the same time and let no light through. I'm guessing this means it's definitely something pretty serious?

Zanxion72 - The display does change accordingly when you select different speeds on the Tv dial.

Xmas - What do you mean 'sticky'? The magnets seem to work smoothly when the shutter is fired and when you wind on the film.

 

[zanxion72]

Perhaps the first and the second curtain have been stuck together. It seems to you that it fires at 1/1000 because both curtains travel to one side with the high speed of the first curtain opening (the first curtain "drags" the second).
Try opening the back, partially wind the shutter until you get the seam of the two curtains somewhere in the middle and with a soft brush try some lighter oil on the seam.

 

[Xmas]

The 2nd curtain is controlled by a solenoid the solenoid is fired after an interval after the 1st curtain starts dependent on the exposure time required.

If the solenoid sticks open the blinds will run together if it sticks closed only the first blind will run?

note I don't have a Canon to hand

 

[John Koehrer]

The 2nd curtain is controlled by a solenoid the solenoid is fired after an interval after the 1st curtain starts dependent on the exposure time required.

If the solenoid sticks open the blinds will run together if it sticks closed only the first blind will run?

note I don't have a Canon to hand

*****What he said.^^^^^
except they're magnets, not solenoids.

 

[Xmas]

*****What he said.^^^^^
except they're magnets, not solenoids.

Hi John

Thanks for that.
My bad English, electro magnets then?
You could use Zippo lighter fluid instead but still darning needle qtips and patience.

Noel

 

[benjiboy]

I think your camera needs some professional attention, if you need it to work correctly again.

 

[HarrietteD]

I've had a go at lightly oiling the shutter curtains but have seen no change. Opening up the bottom, neither of the two magnets stick, they both connect when you wind on the film and then open together when you press the shutter no matter what shutter speed you set. I assume this means it is definitely a fault with the electronic control mechanism or could it be some corroded soldering? Some of the solder points look a little rough and corroded.

 

[Xmas]

Sounds like electronic problem unlikely to be solder joint.

Id find another body... a repair man may be more $.

 

[John Koehrer]

Something else that helps if the magnet's sticky, is an abrasive to clean the contacts.
I use a small strip from one of our dollar bills*. Maybe around 2mm wide. put some alcohol on it,
put it between the contacts; hold the contacts together and withdraw the paper.

*Please don't turn me in to the feds.

If both curtains are running together, the timing magnet isn't holding the second curtain.
The AE-1 had three magnets in it. I surely don't remember what the A-1 had.

The AE had a series of resistors under the speed dial, like a RC timing circuit.

Noel, it's not bad English, it's two peoples separated by a common language.

Hi John

Thanks for that.
My bad English, electro magnets then?
You could use Zippo lighter fluid instead but still darning needle qtips and patience.

Noel

 

[shutterfinger]

Techs use a burnishing tool.
http://www.amazon.com/GC-Electronic...id=1397787402&sr=8-3&keywords=burnishing+tool

 

[John Koehrer]

1/4" may be a tad bit large for the Canon.

 

[shutterfinger]

http://www.amazon.com/ADC-Medicut-S...UTF8&qid=1397882821&sr=1-28&keywords=scissors ?

 

[John Koehrer]

Yep, there's alway a way isn't there?

 

[Andrew K]

Take the top cover off and check for broken tracks on the main PCB. It's not unusual for 1 or more to break where they run over the prism. Running a jumper wire between 2 points on the track will usually fix the problem.

From memory the curtains running together is usuall a PCB or IC fault..

 

[John Koehrer]

Me again,
Another(or the same) thing to look at..........well, anyway.
If the curtains travel together it means that the magnet for the second curtain isn't holding the curtain and the magnets are more likely to fail than the circuit.
If you have a volt/ohm meter, check the coil for continuity. To do this you're going to have to isolate the magnet from the circuit.. Just unsolder one contact on the relay.
I wouldn't hurt to touch up the solder on them. Take the battery out before you use the soldering iron though.

You can also apply a momentary voltage(1.5V) to the mg to see if it pulls in or releases.