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Vasko
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 27, 2005 - 08:08 am: | 
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Hello,
I have a friends camera with the shutter firing at same speed at any setting. it looks to me as if it is stuck at 1/60. the camera fires nicely but at same speed all the time, the battery seems fine. I tried moving the manual shutter speed dial and the ASA dial just to check if there was something stuck but no luck, it does not matter what setting the camera is at, manual or shutter priority. the aperture works fine.
Thanks |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 27, 2005 - 11:35 am: |
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Camera has defaulted to the mechanical sync speed of 1/60th. The battery test circuit working is no guarantee that the power circuit is working. Check that the feed leads from battery box are not corroded/exhibiting high resistance. There is only one discrete transistor in the AE-1, It is a PNP and is situated on the right, front top of the pentaprism (camera in normal operating alignment). This transistor supplies battery voltage to the three IC chips on the flexi circuit. Voltage is only present when shutter button closes main switch - Check that the switch contacts under shutter button are clean and making proper contact if battery voltage not detected at power supply transistor.
Note before starting to remove the controls and top plate of AE-1 - set shutter speed to B and ASA to 3200. This will release most of the tension in the Tungsten Coupling Wire. Remove top with great care - breaking the coupling wire is the most common error in stripping the AE-1. |
Doug Wilson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, December 27, 2005 - 09:41 pm: |
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Are you sure about the 1/60? If the second curtain release magnet coil craps out, the second curtain will release the instant the shutter button is depressed. This will happen at all speeds; Bulb-1/1000. Check resistance at the coil, should be around 200-220 ohms. |
Doug
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 28, 2005 - 01:03 am: |
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Hello
I agree with Doug, I have had a Canon A1 with the same problem, it was the release magnet had gone open circuit. |
Vasko
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 28, 2005 - 02:16 am: |
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Thanks to all, before I start dissasembling the camera I have a few more questions:
how likely is it, any of these parts can be replaced by non AE-1 part? Mind you I am from Macedonia, a small country with no real Canon service, the dealer for Canon returned the camera with an excuse their repair person is ill and never even tried to diagnose the problem.
I downloaded some repair books for AE-1 program, they are pretty detailed, do you think I can rely on them to open AE-1?
my experience with camera repair is mainly with mechanical cameras (simpple ones, yashica mat, Olympus 35, russian cameras) but I have electrical background so I understand what you are talking about anyway.
and finally since the camera is so well kept and beautifull, I feel very reluctant doing anything on it. on the other hand, there is a person that repairs Nikon cameras older ones FE F2,F3... should i give it to him?
Thanks again |
Don
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 28, 2005 - 09:25 am: |
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If it is firing at 1/60th at all speeds then suspect the ccc contact, (the lower of the 2 plates in front of the eyepiece)is shorted to ground. |
Glenn Middleton
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 28, 2005 - 09:51 am: |
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Vasko,
So you are now indicating that your 1/60 was a guess based on the sound alone and not by viewing the shutter blinds through back of camera.
As you have electrical background, you should be able to check the resistance of the second curtain coil very easily. As Doug Wilson indicates if the coil on magnet goes open circuit all speeds will sound the same, as both curtains release simultaneously. Do check if the shutter is opening though, the power distribution from battery to circuit 'boards' is different in AE-1 to other A Series.
AE-1 Program manual is no help in removing the top plate and resetting the exposure meter linkage etc. It will help you locate the position of the magnet coils as basic shutter is the same across the A series, although the Program makes use of Delrin for shutter gearing.
As for part interchange; basic magnet/coils are same but early AE-1 do not have or have different protective covers. There are also various issues of circuits. In practise this means if you are replacing a magnet/coil that is mounted on a rigid circuit board and you replace whole assembly - check the values of the individual components on the boards, otherwise just swap the magnetic 'switch'.
If you are used to working on/soldering modern electronic devices and take care, you will solve the problem. However I strongly advice you to get a copy of the AE-1 repair manual issued by the American National Camera organisation. This manual is based on their Area Repair Seminars/Courses and gives detailed instructions. Anybody who is familiar with the official Canon Manuals will soon realise that they are basically an 'aide memoir' for service personnel who have attended a Canon training course. eg in A1 manual it just says 'Remove Shutter Button' - no indication how or with what. What was OK for the official Canon repairman can be a bit of a worry for the tinkerer 30 odd years on, looking at a mint A1 door stop.
You could always have a word with the Nikon man if you feel uneasy about doing the repair or do not have the correct equipment.
Glenn. |
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