Pentax MX Mirror Box Removal
Sam Gustafson and one other contributor
Last updated on Jul 9, 2026
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Community-Contributed Guide
An awesome member of our community made this guide. It was not created by iFixit staff.
Introduction
Go to step 1 ↓Removing the mirror box is often necessary to troubleshoot issues and access mechanisms for cleaning. The mechanisms on the side and bottom of the mirror box are common sources of a jammed camera.
What you need
Tools
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Remove the lever cap. The cap is reverse threaded.
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Lift off the advance lever.
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Remove the collar beneath the lever.
Ask FixBot
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Set the ISO to 100 and the shutter speed to 1000.
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Remove one pin head screw.
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Lift off shutter speed dial.
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Remove the collar beneath the dial.
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Installation Notes: Make sure that the tab on the shutter speed resistor mates properly with this slot on the shutter speed dial.
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Place a tool in the fork of the rewind shaft. Turn the rewind knob counterclockwise to loosen it.
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Remove the lock ring underneath the rewind knob.
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Remove the cover plate.
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Remove two M1.7 x 3.2 mm screws.
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Remove two M1.7 x 2 mm countersunk screws.
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Lift off top cover.
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The release cable pin in the shutter button is loose and may fall out.
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Apply isopropyl alcohol to soften the leatherette adhesive.
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Turn the self-timer lever to the charged position.
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Peel the leatherette off the camera body, carefully working it over the self-timer lever.
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Remove one loose cover panel.
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Repeat for the opposite panel.
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Unsolder two yellow wires for the aperture resistor.
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Remove four M1.9 x 3.9 mm screws.
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Lift off front board.
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Look for shim washers at the screw locations and note their positions.
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Remove three M1.7 x 2.0 mm countersunk screws.
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Lift off bottom cover.
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Remove loose plastic housing for motor drive contacts.
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Remove four M1.9 x 3.8 mm screws.
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Lift off light baffle.
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Use isopropyl alcohol to soften adhesive and detach wires from the backside of the baffle.
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Unsolder two brown wires for the shutter speed resistor.
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Unsolder one gray for the x-sync.
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Unsolder one white wire for the FP sync.
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Unsolder one green wire for the motor drive connection.
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Unsolder one blue wire for the LED switch.
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Unsolder one red wire and one black wire.
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Open up wire routing guides and remove all wires from them.
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Pull the black and red wires out of the hole in the bottom of the chassis.
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Make sure the gray wire is free and can pull away with the mirror box.
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Remove one M1.4 x 2.8 mm screw and washer.
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Remove one M1.7 x 2.8 mm screw.
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Pull the LED PCB out of the side of the mirror box.
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Loosen the slotted post but do not remove.
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Slide the idler gear back so that it no longer engages with the speed indicator disc.
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Remove two M1.7 x 4.6 mm screws.
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Remove two slotted posts.
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Lift the mirror box up and tilt the top forward to remove it.
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Temporarily install the wind lever and the shutter speed dial.
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Wind the camera.
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Press the shutter release button.
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Release the opening curtain latch. This is usually done by the mirror box but has to be done manually in this case.
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To reassemble your device, follow these instructions in reverse order.
