|The plastic top-left body
cover comes off easily. Underneath I saw the need to remove this
circuit board. The lower left image shows the solder removed and
the right hand image shows the very tidy job I made of re-soldering it
Later I decided I didn't actually have to remove this board and could
work around it, with care.
This particular camera was entering rewind mode when it should be going
forwards resulting in a jammed up camera. It took more than one go
at it to fix it for good.
|The Nikon F4 has proven itself with pros
all over the world. To my eyes, it's the most "inter-locked"
camera ever made. Every little switch or lever on this camera has
another little switch that you have to press first to operate it. ...
cracks me up :)
Check out the insanity and joy of one person's F4
|This little lever here on
the left normally engages the rewind gearing. The interlock for
this lever is inside the cover-plate. The lever was worn out where the
lock grabs it thus allowing it to shift into action if moved while the
camera was being used. The gearing would then jam up.
After replacing the lever with a new item and returning the camera, it
jammed up again after a dozen rolls of film had gone through. The
owner insisted he hadn't moved that lever by mistake. I accepted
that of course and proceeded with a careful disassembly whilst it was
still jammed up.
|The lever in
question, on the right here, is now in operational position (up).
It presses down on another lever (red arrow) which in turn pushes
upwards via a small bearing (orange arrow) on the underside of a cog.
This cog then engages the rewind motor.
Now, given suitable pressure, these two levers were able to slip past
each other as indicated in the circled parts of the next two images.
bird's-eye view of the situation.
The red arrow points to the offending section - properly mated here.
I tweaked (when your repairman says tweaked, he means bent) the metal
lever at the green arrow to mate the faces squarely.
What actually caused the problem in the first place? The shaft (yellow
line) holding the second lever is secured to the plate indicated by the
yellow arrow. This plate is not very stable and the entire
assembly flexes under pressure. If the levers are not carefully
aligned, or if enough repeated pressure is used, the levers will slip
past each other. It really needs a redesigned part to permanently
fix this issue.