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Okto
Tinkerer
Username: Okto
Post Number: 1
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 18, 2006 - 01:25 am: | 
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So. I have a QL17 that my grandfather gave me back when you could still get mercury cells, that has been sitting around in my room for about that long. I recently dug it up to play with it and put a couple rolls through it after reading about it online and thinking, "Hey, I could use a rangefinder, especially one with a fast 40 on the front end."
Popped a 625 zinc-air in, along with an aluminum shim, checked the meter: stuck in the red above 1.7. Nothing will budge it except physically moving the needle.
Here's what I've tried so far:
• Cleaning battery contacts
• Reversing battery polarity (hey, what the heck)
• Tested voltages at various points: 1.3V-1.4V at all the points I would expect it
• Testing the CdS cell: it responds to light as it should, but i don't know what the specific resistances should be.
So I'm at the end of what I know to check.
Everything else works:
shutter fires,
aperture stops down correctly,
film advance works,
focusing does what I expect.
I haven't put any film through it yet, so I don't know anything about the optics or accuracy of apertures or focus.
Is it a dead galvanometer? That's my best guess at this point. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 31
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 18, 2006 - 02:01 pm: |
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You've got to make sure that the contacts in the battery box REALLY get in touch with the battery poles. What points did you check for the correct voltage (with a battery installed in the battery case, I guess)? Three in five "defective" Canonets I own showed a broken plastic part in which the contacts are embedded. AND: the meter is off in manual mode! W. |
Okto
Tinkerer
Username: Okto
Post Number: 2
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 18, 2006 - 04:29 pm: |
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I checked the volatage between camera chassis ground and positive wire from battery box, and by the battery test lamp.
Thanks for the heads-up on the meter being active only in auto. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 32
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 19, 2006 - 08:57 am: |
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Hi again, I am not a Canon expert, but have somehow managed (with one catastrophic exception) to get all my Canonets going. Try this link: http://homepage1.nifty.com/fukucame/tips/ql_t.htm
It shows the contacts and a switchboard behind the nameplate. On one of my cameras there was so much grime (splashes from spilled liquid?) on them that the light meter was way off. After cleaning everything (cotton swabs, lighter fluid) everything went back to normal.
You should also try Rick Oleson's repair tips, among other things his sketches show how the meter needle can be blocked by either the serrated part of the needle trap mechanism or too tight bearings (this would explain why your meter does not work while the wiring is obviously alright), W. |
Okto
Tinkerer
Username: Okto
Post Number: 3
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, September 20, 2006 - 02:45 pm: |
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Checked the meter trap system, it works like it should and stops the aperture down correctly (for whatever position the needle is in), and loosened the bearings a bit. Still no meter movement.
Is there any way to test the meter itself? |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 34
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 21, 2006 - 08:38 am: |
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Rick's Tech Notes show a Canonet with its top cap removed, offering acces to the wiring around the meter. I have just tried this on a GIII junker, and I carried out a similar test on a similarly designed Minolta Hi-M 9 earlier.
Try to touch the soldering joints on the ends of the trim potentiometer's red wires there are with a battery-powered multimeter's test cords (as if you were measuring low resistances), on touching them the meter's needle should immediately respond to electric current passing through. If not, this does not necessarily indicate the meter is broken, but for details one would need a wiring diagram (which I do not have, sorry). This is to say if a wire is broken somewhere deeper inside (under the bottom plate or on the right underneath the sheet metal covering) it will not be easy to fix, I guess, as this requires a more internal examining of the wires (especially the blue one leading to the meter!). This is just a theory as I have not done that repair myself. Maybe somebody else has more knowledge than me about a Canonet's "internal affairs" !? |
Greyhoundman
Tinkerer
Username: Greyhoundman
Post Number: 1
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, September 21, 2006 - 12:45 pm: |
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First thing to check is the battery wire from the battery compartment. Known for corroding off. |
