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Message |
    
Jim_metcalfe
Tinkerer
Username: Jim_metcalfe
Post Number: 4
Registered: 10-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 22, 2009 - 06:23 pm: | 
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My old MX seems to have dirty sync contacts. With an old, high-voltage flash like a Vivitar 283, it syncs about 80% of the time. With a newer flash with low trigger voltage, maybe 5%. Is there an easy way to get at the contacts? I've seen the exploded diagrams, but they're not much help. |
Sardines
Tinkerer
Username: Sardines
Post Number: 3
Registered: 10-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 22, 2009 - 06:42 pm: |
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Give the PC tips on both the camera and flash cord a spray of contact cleaner (likr 5-56 electronic contacr cleaner).
If that doesn't work, get a hotshoe to PC adapter from Porters.com which will convert your hotshoe to accept the PC corded flash.
If none of that works, consider dirty flash contact points internally and wait for someone who knows to explain how to fix that. |
Jim_metcalfe
Tinkerer
Username: Jim_metcalfe
Post Number: 5
Registered: 10-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 23, 2009 - 10:18 am: |
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Thanks, I should have been more clear. I mean the internal contacts. The problem is the same with both the hot shoe and the pc connection. |
John_shriver
Tinkerer
Username: John_shriver
Post Number: 51
Registered: 12-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, December 05, 2009 - 06:09 pm: |
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Service manual at:
http://www.robertstech.com/files/mx_sm.pdf
The contact is assembly O-J621. It is not under the bottom plate. I think it's behind the PC connectors. You at least have to peel the fake leather off the front and remove the lens mount. (Don't misplace the shims!) I don't remember if it's well accessible at that point, or if you have to pull the mirror box to get at it.
While the MX is really pretty nice for pulling the mirror box as SLRs go (two screws, and the annoying shutter speed indicator), that's a moderately severe teardown. You may have to recalibrate focus (mirror stop) afterwards. You'll also have to replace a lot of crumbling internal light seals for having opened the guts.
Note it may also be a cold solder joint instead of a bad contact. Making good solder joints with thin stranded wires to PC boards with no mechanical connection is tricky. Use 63/37 eutectic solder. |
