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Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 37
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, November 07, 2009 - 09:13 pm: | 
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I recently acquired a Canon FTbn in good overall condition except the meter does not respond. I replaced the long-dead 625 battery with a Wein cell, and the meter needle responds normally now when the switch is set to the "C" (for check) position. But the needle does not deflect at all when the switch is set to "on" and the camera is pointed at an adequate light source.
It's been quite a few years since I've had the covers off an FTb, and I'd just as soon not be flying blind anyway. So, is there any component/area that I should look to first as a most likely culprit? And perhaps more importantly, should I actually need a part, is there a source for meter parts for these old Canons anymore these days?
Okay, about the focusing screen -- the foam mirror bumper has rotted away, leaving behind a sticky residue, and somebody must have wiped a portion of this stuff across the focusing screen, probably when trying to remove rotting pieces. What would be the best way to clean the screen without having to remove it (which requires dismantling the top end of the camera)? I'm thinking alcohol and a very tiny brush sold by International Violin, which is used by violin makers as a finish touch-up tool. I have a stash of these. But perhaps another solvent might work better? Naphtha? Acetone? ???
Thanks,
Michael |
Gez
Tinkerer
Username: Gez
Post Number: 156
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, November 08, 2009 - 03:25 am: |
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There is lots in the archive wrt removing the top cover. If the meter responds at the C position it is probably OK. I suspect the camera has been worked on and the metering rack has not been properly reset, also the pots maybe out of adjustment. It is not unusual for the metering, even for an FTb in original condition, to be out by 2 stops. The CdS cell age or the neutral density filter in front of the cell gets dirty.
DON'T let acetone get anywhere near the screen! Lighter fluid is OK. There are a variety of opinions regarding how to clean a screen. I have found 100% methyl alcohol effective. Wet the end of a cotton tip and and just touch the screen with it, no direct pressure or rubbing. The residue almost dissolves in the alcohol. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 38
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 09, 2009 - 12:46 am: |
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Thanks for the response, Gez. I'll go to the archives and have a look-see.
If the camera has been worked on by a competent repair tech, it hasn't been within the past decade or so, I would wager. The entire camera could use a thorough cleaning.
Glad to hear about the "C" responding being good news. I've always had a soft spot in my heart for the FTb -- it was my first "real" camera (I "graduated" from an A-1 to an FTb, at which time I began learning about photography), and I'd like to get this one back up to par.
Actually, now that I'm thinking about it, especially after reading your comment, I realize now that I should probably have mentioned one other thing I noticed. The meter needle does move when I adjust the shutter speeds. But only when I get all the way down to 1/2-second and slower. It doesn't respond to light, it just moves a give amount for 1/2 second, 1 second, and B. So, I was presuming that this was a function of some sort of coupling mechanism -- perhaps the rack you mentioned?
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Dragunov
Tinkerer
Username: Dragunov
Post Number: 156
Registered: 10-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, November 09, 2009 - 01:41 pm: |
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it might be dirty contacts under the switch plate thingy. mine is a bit iffy too. just take the cover off and mess with 'em a bit, see if that works...
the needle is supposed to move at a certain point. if you set the shutter speed to, say, 8 and mess with the ASA, the needle might move or might not move. that comes from the rack and pinion... it's mechanical compensation for the out-of-range areas of the meter.
by the way- set the shutter speed dial to 1/1000 and ASA 8 or 6 or 25 or whatever the lowest is. the black marker marks where the shutter speed dial peg goes. don't mess with the rack and pinion stuff if you don't have to...
and the FTb was my first real camera too. also my first successful CLA. pretty easy camera to work on too...
good luck! |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 47
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, December 09, 2009 - 07:44 pm: |
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I just thought I'd resurrect this thread to let you folks know that I figured out how to get the meter on this old FTb to work. I have to sort of push on the meter on/of/battery check switch a certain way and it comes on. So this has me thinking that there's probably just some oxidized contacts or the like under the top cover.
Comparing the meter to that on my F-1, which is dead nuts accurate, it's overexposing between 1/2 and 1 stop. Certainly within an acceptable amount for most print films, but I shoot slides. So I'll be looking at a way to tweak the meter to bring it back into spec.
Even though I can probably figure out how to do the meter switch repair without a manual, I'm not sure at all how to adjust the meter to get it to read accurately. So I'd like to find a repair guide. I've searched the web high and low for a .pdf for the FTb (mine's an "n"), and have run across a few places that sell the pdf or the manuals in print form, but no free links. I don't mind buying a repair guide, but I've been burned before buying supposedly comprehensive and complete repair guides for my cars that were just about worthless, and I'd just as soon avoid this with my FTb. So if there are any places out there you can recommend I'd appreciate it. And I'd also prefer to find a guid that's more than just a parts list with a bunch of exploded diagrams too.
Michael |
Gez
Tinkerer
Username: Gez
Post Number: 162
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 10, 2009 - 02:38 am: |
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A good place for reasonably priced factory manuals is www.lensinc.net. The one for the FTb has some good 'how to' sections, particularly on resetting the meter. You may also wish to buy the FD lens guide. It doesn't give detailed disassembly instructions, but lists the aperture diameters at various F stops. This info is essential for correct adjustment of the iris assembly after cleaning. |
Cooltouch
Tinkerer
Username: Cooltouch
Post Number: 48
Registered: 01-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 10, 2009 - 01:07 pm: |
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Thanks, Gez, I'll give lensinc a visit. Is this FD lens guide different from the FD lens guide that Canon used to include with all the FD lenses it sold? If not, I have a few different copies of it. |
Gez
Tinkerer
Username: Gez
Post Number: 163
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, December 10, 2009 - 02:06 pm: |
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The FD lens guide is a typed document intended for use in their service centres. It appears to be from Canon's glory days of the mid 70's. Certainly worth having if you intend major surgery on the old FD breechlocks. |
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