Pentax ZX-5n Mirror Motor Gear Replacement

Geschrieben von: Sam Gustafson
  • Kommentare: 4
Pentax ZX-5n Mirror Motor Gear Replacement

Schwierigkeitsgrad

Difficult

Schritte

36

Zeitaufwand

2 Stunden

Einleitung

A common failure of the Pentax ZX/MZ cameras is the Mirror Motor Gear. The gear drives core functions of the camera including the shutter and mirror movement. If it fails, the shutter will no longer fire and the mirror will be stuck close in the up position.

This guide explains how to disassemble the camera to access the Mirror Motor Gear as well as how to install a new gear. A general understanding of how cameras work is recommended. Some technical soldering is also required.

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    • Push down on the screw to depress the spring loaded hinge and release the door.

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    • Remove six 5.3 mm #00 screws.

    • Remove one 3.4 mm #00 screw.

    • The short screw has a machine thread and screws into the plate underneath. The rest screw into the plastic body.

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    • Remove three 5.3 mm #00 screws (the bottom-most screw is not always present).

    • Remove one 7.3 mm #00 screw.

    • Remove the remote trigger cover.

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    • Remove one 3.4 mm #00 screw.

    • Remove two 5.3 mm #00 screw.

    • Gently lift up on the flash housing to help remove the cover if necessary.

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    • Remove two 3.9 mm #00 screws.

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    • Slide the eye cup up and off to access the screws underneath.

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    • Remove two 5.3 mm #00 screws by the eyepiece.

    • Remove one 6.8 mm #00 screw in the battery compartment.

    • Remove one 7.0 mm #00 screw near the take up spool.

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    • Lift the cover so it is just free of the body. It is still attached by several wires.

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    • Use a 1kΩ-10kΩ resistor to discharge the capacitor. Place the resistor between the blue wire, exposed in the previous step, and ground.

    • The flash capacitors store energy at a very high voltage. Failing to discharge the capacitors properly could result in personal injury and/or damage to the camera.

    My camera doesn't have the same yellow connection point (is it apart of the camera or your own). I was wondering if there was any other way to discharge the flash capacitors? And how do I know when I've completed the step, any sound cue? Thanks in advance.

    tarek tarek -

    The yellow piece you see in the picture is a resistor covered in heat shrink tubing. When you discharge the capacitors, you are making a connection between the high voltage pin and ground, which allow the energy to flow out. The resistor is there to slow the current and have a safer discharge. If you don't have a resistor in the range listed, picking something higher will still allow a safe discharge but it will take longer. With a 10 kOhm resistor, it usually takes about 10 seconds to fully discharge. I check the voltage with a meter to make sure it's at a safe level. There isn't really an audible or visual cue to know whether it has discharged.

    Sam Gustafson -

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    • De-solder the green, blue, brown and black wires from the flash PCB.

    When soldering the connections, what temperature would you recommend?

    tarek tarek -

    I'm not sure what the optimal temperature is. My soldering iron is set at 380 C but that might be a little on the high side.

    Sam Gustafson -

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    • Move the top cover to the side to access the battery connections. It is still connected by a flex cable.

    • De-solder the indicated joints. Use a solder sucker on the tabbed connections.

    • Pull the black wire from the battery flex to get more slack in the connection to the top cover.

    • Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

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    • Use a solder sucker to de-solder the four posts from the flex circuit.

    • This is the most difficult part of the repair. Patience and persistence are required.

    • Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

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    • De-solder the marked connections.

    • Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

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    • Remove one 4.3 mm #00 screw.

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    • Gently pry up the plastic carrier under the flex circuit. It may catch slightly on the battery contact tab.

    • Pay close attention to the connections around the four through-hole posts as you lift the flex. Make sure that no solder is left over and that it pulls away freely.

    • This metal tab is lightly held in place with lacquer and can easily come loose. Keep an eye on it.

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    • Remove one 3.3mm #00 screw.

    • Remove one 3.9 #00 screw.

    • De-solder the red wire.

    • Peel off the black tape. Leave it attached to the wires.

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    • Gently peel the flex circuit from the surface of the capacitor.

    • There may be additional adhesive underneath the larger capacitor.

    • Lift the two capacitors and the flash PCB out as a single unit.

    • The contact cement used to secure the capacitors can be softened with isopropyl alcohol if necessary.

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    • Remove two 3.4 mm #00 screws. Remove the plate holding the contacts in place.

    • Peel tape from the plate. Leave the tape attached to the flex circuit.

    • Remove the flex circuits from their retaining studs.

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    • Remove one 3.3 mm #0 countersunk screw.

    • Remove one 3.9 mm #0 shoulder screw.

    • Remove four 3.3 mm #00 screws.

    • Pull a little slack through the housing on this flex cable.

    • Pop the plate off its posts, rotate slightly clockwise and pull gently through the loosened flex cable.

    • To the camera tech that left me a happy little note...I see you.

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    • It's best to remove these parts now so they don't fall out later on in the repair.

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    • Remove one 3.8 mm #00 screw.

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    • De-solder the connections.

    • Lift the flex off the retaining studs.

    • Be careful not to overheat the flex circuit. Work in short durations. Allow for cool downs in between if necessary.

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    • Remove two 5.3 mm #0 screws.

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    • Remove two 7.4 mm #0 screws.

    • Remove one 8.3 mm #0 screw.

    • Remove one 3.3 mm #00 screw. The metal bracket will be loose and should be removed as well.

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    • Push the front housing block slightly up then lift the left side up and away from the housing.

    • Proceed slowly and watch for any components that are catching. The right side is still attached by a large flex cable.

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    • There may be shims at the mounting points of the front housing block.

    • Note the positions and remove the shims.

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    • De-solder the black wire.

    • Remove four 3.7 mm #00 screws.

    • Detach the buzzer from its mounting posts. Use isopropyl alcohol to soften the lacquer if necessary.

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    • Grab the motor and gently wiggle the plate loose.

    • If it feels stuck, move the sliding plate down, towards the bottom of the camera

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    • De-solder the red and black wires.

    • Remove two #00 screws.

    • Use the lettering on the motor to note its orientation. If installed or wired backwards, the motor will spin in the wrong direction.

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    • Pull off the old gear.

    • Press the new gear on until about 1 mm of the shaft extends past the end.

    • If it is too difficult to press on, use a soldering iron to heat the brass gear. A small amount of thermal expansion should make it easier.

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    • The green and yellow gears can sometimes slip off their posts while working with the motor.

    • Check that the alignment holes are properly synced before installing the mirror motor assembly.

    • Aperture set lever spring. Note this part for installation of the mirror motor assembly.

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    • Disengage latch so the slide bar can move freely.

    • Move the slide bar about half way down its total travel.

    • Let the latch snap back into place so the slide bar is held in the new position.

    • This ensures that the aperture set lever spring couples properly with the slide bar during reassembly.

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    • Install the mirror motor.

    • Place the left side first. Then swing the right side in, coming up and under the spring loaded lens release.

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    • Rotate the grey gear downward until the mirror is in the charged/down position.

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    • Push the shutter charge lever upward. You should see the shutter blades move as you do this.

    • The second picture shows the shutter in the charged position. It may already be in this position and not need charging.

    • Gently place the front assembly block. Work it into place until the back of the block is flush to the back of camera.

    • Proceed with the rest of the re-assembly, following the guide in reverse.

Abschluss

To reassemble your device, follow these instructions in reverse order.

Tinte & Feder

Sam Gustafson

Mitglied seit: 02/09/22

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