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FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
Thread started 10 Mar 2018 (Saturday) 18:23
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Canon EOS40D

 
johny55
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Mar 10, 2018 18:23 |  #1

For 'the fun' i try to repair a EOS40D.
The problem is that the shutter doesn't open. Mirror goes up, shutter stays closed and message err 99 comes up.
With mode sensor manual cleaning the same. Shutter does not open.
I disassembled the camera already 2 times, mounted new shutter blades with no result.
Today i wanted the know the voltage that shutter and mirrror motor need. I used a oscilloscope to measure it.
The shutter motor becomes a 7,8 V pulse
The mirror motor becomes a pulse of -7,8 V .... MINUS 7,8V !!!
Can anybody from this forum tell me if thats correct?




  
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BigAl007
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Post edited 3 months ago by BigAl007 with reason 'extra info'.
     
Mar 10, 2018 18:57 |  #2

Having been an electronics tech in the RAF, I just want to double check with you that you are picking up your ground from the exact same point in the camera for each measurement? Also just to be sure you are using a ground reference that you are picking up from the camera? Preferably using the ground connector/sheild on a decent quality scope probe.

I remember how easy it is to make a simple unnoticed error. I remember once spending several hours working with a couple of other techs trying to calibrate some power supplies. We could not get the output voltages anywhere near correct, which was not good news as we were in the radar stations main timing generator. Turned out that someone had plugged the oscilloscope into the mains socket on the adjacent rack for convenience. The problem was they were taking the ground reference from the earthed mains input to the scope. Turns out that the two racks were on different earths and there was a difference of IIRC 70V between the two different ground references. It wasn't normally an issue, since the other rack they used for the power connection wasn't part of the timing generator. There was probably a total of 20 man years total experience working on that problem, and it still took two hours to figure out the trouble.

Also don't forget that there are a wide number of DC-DC converters now avilable in any number of voltage combinations and packages. I very quickly found this 5V in ±12V out 2W in a SIL package on the Rapid website (external link).

Alan


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johny55
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Mar 10, 2018 19:14 as a reply to  @ BigAl007's post |  #3

Hello Alan,
First of all thanks for your reply.

There are 2 motors as i mentioned before. Both have a red and black wire that go to different connectors at the main PCB.
Both black wires are not connected with each other i found out with a multi meter.
Thats why i tought both motors might have their own ground. Sort of separated power supplies.
In fact i was hoping somebody would reply by saying he/she had the same probolem, and there is something wrong with the powersupply from the mirror motor.
Both black wires are not connected with each other, but also not with any metalic part of the camera, or a connector.
If they wanted to let the motor turn the other way, they could have changed the wires on the motor side.
I am confused, but maybe there is a logic behind it.




  
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BigAl007
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Mar 11, 2018 08:33 |  #4

If they use the exact same motor in two different functions, assuming that are straight normal brushed DC motors, the simplest way to get them to rotate in opposite directions is to switch the polarity. If they are the same component then you are not going to swap the colours of the wires at the motor end, that would be silly since then you create two different components, where one would do.

The wiring colours are just arbitrary choices anyway. For example I always use pink insulation for off board connections of signal carrying interconnects when designing equipment. I choose that colour simply because the main radar system that I worked on when in the RAF, the AEI (later taken over by Marconi) Radar Type 85 used that convention, and I like it

If I were trying to do blind fault finding like this using a multimeter and oscilloscope I would use the negative end of the power source, in this case the negative end of the battery as my ground/0V reference. That should allow you to check that the power board is producing the voltages that you expect it to. Hopefully each of the power regulators will have some component identification that will allow you to look it up. If the PSU side checks out hopefully it won't be too much of a job following the circuit back through the drive stage for the shutter motor, although that will of course depend on the number of conductor layers in the PCB. Should be OK if it's only dual layer. A multilayer board will complicate matters, and you would probably need a full circuit diagram. With a bit of luck it will be a problem in the output driver that is fixable. If it's a problem in the actual logic then it's probably replacement board time.

Alan


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johny55
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Mar 11, 2018 09:33 as a reply to  @ BigAl007's post |  #5

Hi Alan,
Thanks for your detailed comment.

On the right side you can see the mirror motor, and on the left side is the shutter motor, that you can't see. Only the gear is vissable.
Downunder the red/black wires are vissible, and the connector dissapears behind the yellow tape.
Measuring on the ground from the batterie is possible, but i think it doesn't make any sence, because i wanted the know what power the motors need, and in my opinion can be achived with direct measurement at the motor.
In several documents i read so far, they are talking about a 'phase sensor from the shutter cocking unit'.
I have no idea where to find that sensor, tough it sounds logical that the computer from the camera should be informed what the position from the mirror motor is, when the mirror is up , and when the shutter can be opened.
I could imagine something is wrong with that sensor. When the computer tells the mirror motor to start and there is no information comming back that the mirror is up , so the shutter can be opened, this ends in a err99.
I understand you are a electronc man with a lot of experence, and i think you had also different 'attack strategies' by 'attacking' a electronic problem.
Since that sensor thing didn't bring me any further, i tought about checking the power on both motors.
Maybe another forum member is reading with us, and can bring light in darkness.


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