problem: M6 stays at 6400 iso

[imported_reinierv]

Can anybody tell me what the probable cause is for this problem I have with my M6. Everything is working just fine but I can't modify the ISO value, it seems to stay at 6400 eventhough I can move the dail.

If I remove the pressure plate, can I then access the dail mechanics?

[andybarton]

Originally Posted by imported_reinierv

Can anybody tell me what the probable cause is for this problem I have with my M6. Everything is working just fine but I can't modify the ISO value, it seems to stay at 6400 eventhough I can move the dail.

If I remove the pressure plate, can I then access the dail mechanics?

Taking the camera apart doesn't sound like a very good idea to me

When I first got my R8, it was permanently set to 100 ISO. In order for me to get it to set via the DX Code, I found (with help from the kind folks here) that I have to go right to the top of the scale, to ISO 10,000 and then one step more brought back the DX code setting.

I don't have an M6, but this something similar may be occuring there.

Have you tried speaking with your local Leica office, or the person who sold you the camera?

[marknorton]

The Film Speed Dial is a potentiometer - which is just like an old style volume control. This has three connections to the camera which are made when the film loading flap is closed.

First thing to do is to check that the 3 gold contacts contacts are sprung - they should move in when you press them and spring back freely when you let go. Then the contacts on both the flap and the camera should be clean. If in doubt, use a Q-tip dipped in lens cleaning fluid to clean them.

If that all seems fine, you need to do some resistance checks. Borrow a voltmeter - you can buy them from hardware or electronics shops if you do not have one - and measure the resistance between the pins.

With the flap open, counting the top connection (furthest from the hinge) as 1 and the bottom one as 3....

Set to ISO 6 (!):

1 to 3: 29.5k Ohms
1 to 2: < 100 Ohms
2 to 3: 29.5k Ohms

Set to ISO 6400:

1 to 3: < 100 Ohms
1 to 2: 29.5k Ohms
2 to 3: 29.5k Ohms

You can see that as you move the ISO dial from one end to the other, pin 1 moves from being connected (low resistance) to pin 2 to being connected to pin 3.

If you don't get similar figures, the resistive track is probably cracked and will need replacing.

[imported_reinierv]

Thanks Mark

I will give it a try but that seems to be the case unless a wire got loose...I have an electronics background so this should be easy for me, I have a resistance meter at home ;-) The gold springs were the first ones I checked, they are ok and CLA's only 6months ago. It occured after I slid down a bumby snowfield in the alps last week, camera in its own bag on the side of my backpack, so indeed something may got broken as the dail was pushed a little inward.

I guess it is thus easy to remove the film-pressure plate to check the wireing and the potentiometer. Does Leica send parts to individuals for repair? If so who should I contact.

[marknorton]

I think the problem will be that if even if you were to replace the potentiometer yourself, the meter will need re-calibrating...

[imported_reinierv]

well I openend the camera and checked...all values stayed at infinity.

I opened the iso setting mechanics and indeed the ceramic plate had a crack...so I'll have to send it out for repairs...

thanks

[areshuan]

Dear all:
I have the same problem . And I wonder if you had any good results replacing the resistor.
Thanks

Alex

[marknorton]

Well, it's not just a resistor, it's a ceramic substrate with a carbon track deposited on it. In theory it's a user replaceable item (if you are reasonably capable with small tools) but the light meter likely needs re-calibrating after replacement, so it's back to Leica (or another repairer). See my comments above.

[areshuan]

Thanks Mark:
I have contacted some Leica repairmen . I got this from one of them:

"there's probably a loose wire or other open circuit in the ASA circuit of the backdoor. If you want this repaired it'll probably be $30.00 plus return shipping, the backdoor comes off the camera quite easily by lifting the door up, push the cross-head screw just to the right of the left hinging pin towards the center of the door & that left hinged area will free it's self & take the door off the camera
-------------
Sounds like both LED red triangles work so that's a good sign. I've seen this problem many times before so I really think that's what the problem is. There's a smal ceramic circuitboard inside the backdoor & I'be never seen one that needed replacing. My computer goes back to the year 2000 & I show that I repaired 892 M6 cameras & none of them had a broken backdoor circuitboard."