Canon T70 repair & common faults
Excellent coverageThe T70 was Canon's 1984 advanced amateur SLR, the first Canon body with a motor drive built in rather than bolted on, and the first to swap needles for an LCD data panel. A microprocessor runs its program, aperture priority and shutter priority modes, so its ageing electronics and drive train are what usually decide whether one still works.
Program, aperture-priority and shutter-priority AE · Electronically controlled vertical shutter · Built-in motor drive · 3-zone metering · 4 × AA batteries · Canon FD mount
Common Canon T70 faults
Canon T70 won't turn on, blank display
A blank display and no response usually means power isn't reaching the electronics, and on the T70 that's often corrosion on the battery contacts from leaking cells rather than the circuit itself. The microprocessor needs clean contact to do anything, including fire the shutter. Try a fresh set of four AA cells first; if the display stays dead, the fault sits in the contacts or the electronics beyond.
Canon T70 film won't advance
The T70 was the first Canon SLR with the motor drive built into the body, winding on and rewinding automatically instead of by hand. When advance stalls, grinds or stops partway through a roll, it usually points to wear in that drive train or dirt in the gearing rather than a problem with the film. Check the cassette is seated properly first; ongoing stalling points to the drive mechanism itself.
Canon T70 blank or unevenly exposed frames
This points to the electronically timed shutter not opening and closing evenly across the frame, which becomes more likely with age as the magnets and timing circuit governing the curtains drift. It shows as a dark band across the frame, or occasionally a fully blank one, rather than a gradual dimming of the image. It's a fault in the shutter and its electronics, not something a battery change will fix.
Canon T70 mode dial or buttons not working
The T70 selects program, aperture priority and shutter priority modes through electronic switches and a contact strip under the mode dial rather than a mechanical linkage. Wear or dirt on those contacts causes mode selection to stick, skip a setting or stop responding, with the LCD confirming whatever mode it thinks it's in rather than what's dialled. It's a contact and switch fault behind the dial, not the exposure system.
Canon T70 exposures consistently wrong
If exposures come out consistently wrong in good light with fresh film, the metering cell or the circuit reading it is the more likely cause rather than the shutter. The T70 divides the frame into zones to bias exposure toward the centre, so a genuine metering fault tends to affect all three exposure modes rather than just one. Check the film speed setting hasn't been knocked first; otherwise the fault is in the meter.
Canon T70 mirror stuck up
A mirror that stays up after firing, blacking out the viewfinder, points to a fault in the mirror and shutter cycle that the motor drive controls. Because the T70's film advance and mirror return are both handled by the same built-in motor rather than a manual wind lever, a single fault in that mechanism can leave the mirror parked instead of just slowing the wind. It isn't something a battery swap alone will clear.
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Try it now ›Scatto is a reference tool for people who service film cameras. It explains mechanisms and quotes service data, but it cannot see your camera at the bench, so verify anything load-bearing before you act on it.