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Pentax LX Main PCB Removal

Introduction

Any disassembly of the LX body will compromise the weather sealing. New seals must be reapplied during final reassembly to restore weather proofing.

What you need

  1. Pentax LX Main PCB Removal, Remove rewind knob: step 1, image 1 of 2 Pentax LX Main PCB Removal, Remove rewind knob: step 1, image 2 of 2

    • Place a thin tool in the rewind fork and unscrew the topside knob.

    • Remove the washer under the rewind knob.

    Edit

  2. Pentax LX Main PCB Removal, Remove exposure compensation dial: step 2, image 1 of 3 Pentax LX Main PCB Removal, Remove exposure compensation dial: step 2, image 2 of 3 Pentax LX Main PCB Removal, Remove exposure compensation dial: step 2, image 3 of 3

    • Remove three #000 5.5 mm screws.

    • Remove exposure compensation dial assembly.

    • Remove washer.

    • Remove rubber seal.

    Edit

  3. Pentax LX Main PCB Removal, Remove rewind side top cover: step 3, image 1 of 2 Pentax LX Main PCB Removal, Remove rewind side top cover: step 3, image 2 of 2

    • Remove one #00 X mm screw.

    • Remove one #00 2.5 mm screw.

    Edit

  4. Pentax LX Main PCB Removal, Remove winding lever: step 4, image 1 of 3 Pentax LX Main PCB Removal, Remove winding lever: step 4, image 2 of 3 Pentax LX Main PCB Removal, Remove winding lever: step 4, image 3 of 3

    • Winding lever cover is reverse threaded.

    • Use a piece of tape wrapped sticky side out to grip the winding lever cover. Turn clockwise to loosen and remove

    • Remove four #000 2.5 mm screws.

    • Use spanners to remove top cover retaining nut.

    Edit

  5. Pentax LX Main PCB Removal, Remove shutter speed dial: step 5, image 1 of 3 Pentax LX Main PCB Removal, Remove shutter speed dial: step 5, image 2 of 3 Pentax LX Main PCB Removal, Remove shutter speed dial: step 5, image 3 of 3

    • Gently remove the rubber covering around the shutter speed dial.

    • Remove three #000 1.6 mm screws.

    • Remove cover ring.

    • Installation Notes: After the camera has been fully tested, use a few dabs of contact cement to fix the rubber covering back in place.

    Edit

  6. Pentax LX Main PCB Removal, Remove wind side top cover: step 6, image 1 of 3 Pentax LX Main PCB Removal, Remove wind side top cover: step 6, image 2 of 3 Pentax LX Main PCB Removal, Remove wind side top cover: step 6, image 3 of 3

    • Remove one #00 2.5 mm screw.

    • Remove one #00 X mm screw.

    • Lift off top cover.

    Edit

  7. Pentax LX Main PCB Removal, Remove bottom cover screws: step 7, image 1 of 3 Pentax LX Main PCB Removal, Remove bottom cover screws: step 7, image 2 of 3 Pentax LX Main PCB Removal, Remove bottom cover screws: step 7, image 3 of 3

    • Remove the rubber bumper covering the screw.

    • Remove one #00 1.8 mm screw.

    • Repeat on the other side of the bottom plate (#00 3.0 mm screw).

    Edit

  8. Pentax LX Main PCB Removal, Remove bottom cover: step 8, image 1 of 1

    • Remove one #00 3.0 mm screw.

    • Remove bottom cover.

    Edit

  9. Pentax LX Main PCB Removal, Remove front leatherette: step 9, image 1 of 2 Pentax LX Main PCB Removal, Remove front leatherette: step 9, image 2 of 2

    • Use isopropyl alcohol to soften the adhesive along the edge of the leatherette.

    • Use a dull spudger or scraper to peel off the covering.

    • Turn the self timer lever to the 9 o'clock position.

    • Loosen the entire right side leatherette in the same manner, then work it over and around the self timer lever to remove.

    • Installation Notes: Use contact cement to reattach the leatherette. This should be the very last step in reassembly, after the camera has been fully tested.

    Edit

  11. Pentax LX Main PCB Removal, Remove two cover plates: step 10, image 1 of 2 Pentax LX Main PCB Removal, Remove two cover plates: step 10, image 2 of 2

    • Remove the two cover plates under the leatherette.

    • They may stick to the covering adhesive and come off on their own.

    • This small plug may also be loose.

    Edit

  12. Pentax LX Main PCB Removal, Unsolder relay board: step 11, image 1 of 2 Pentax LX Main PCB Removal, Unsolder relay board: step 11, image 2 of 2

    • Unsolder one gray wire.

    • Unsolder two yellow wires.

    • Unsolder one blue wire.

    • Unsolder one red wire.

    Edit

  13. Pentax LX Main PCB Removal, Remove front lens board: step 12, image 1 of 3 Pentax LX Main PCB Removal, Remove front lens board: step 12, image 2 of 3 Pentax LX Main PCB Removal, Remove front lens board: step 12, image 3 of 3

    • Unscrew four #00 X mm screws.

    • Unsolder one white wire.

    • Unsolder one pink wire.

    • Unsolder one light green wire.

    • Check the mounting points for shim washers. If they are loose, note the position and remove.

    • Installation Notes: Check the function of the self timer and the depth of field preview lever after install.

    Edit

  14. Pentax LX Main PCB Removal, Remove light seal frame: step 13, image 1 of 1

    • Remove four #000 1.8 mm screws.

    • Remove the light seal frame.

    Edit

  15. Pentax LX Main PCB Removal, Unsolder exp/ISO resistor: step 14, image 1 of 3 Pentax LX Main PCB Removal, Unsolder exp/ISO resistor: step 14, image 2 of 3 Pentax LX Main PCB Removal, Unsolder exp/ISO resistor: step 14, image 3 of 3

    • Unsolder one pink wire.

    • Unsolder one purple wire.

    • Unsolder one green wire.

    • Unsolder two yellow wires.

    • Unsolder two brown wires under the loop of flex cable.

    • Unsolder one gray wire.

    Edit

  16. Pentax LX Main PCB Removal, Remove exp/ISO resistor: step 15, image 1 of 3 Pentax LX Main PCB Removal, Remove exp/ISO resistor: step 15, image 2 of 3 Pentax LX Main PCB Removal, Remove exp/ISO resistor: step 15, image 3 of 3

    • Unscrew three #00 3.0 mm screws.

    • Remove exp/ISO resistor assembly.

    • Remove exp. compensation coupling cam.

    • There are two loose ball bearings that sit in these holes. Do not lose.

    • Installation Note: Push this lever back to properly seat the exposure compensation lock. Check that the flag in the viewfinder is working properly. It should not be visible when dial is set to 1x and pop into view when set to any other value.

    Edit

  17. Pentax LX Main PCB Removal, Detach metering cell PCB: step 16, image 1 of 1

    • Remove two #000 screws.

    • The PCB will remain attached but can move out of the way for soldering access.

    Edit

  18. Pentax LX Main PCB Removal, Unsolder adjustment PCB: step 17, image 1 of 2 Pentax LX Main PCB Removal, Unsolder adjustment PCB: step 17, image 2 of 2

    • Unsolder five black wires.

    • Unsolder two green wires.

    • Unsolder one purple wire.

    • Unsolder one yellow wire.

    • Unsolder one orange wire.

    • Unsolder one light brown wire.

    Edit

  19. Pentax LX Main PCB Removal, Remove battery compartment: step 18, image 1 of 2 Pentax LX Main PCB Removal, Remove battery compartment: step 18, image 2 of 2

    • Unscrew two #00 2.5 mm screws.

    • Unsolder one red wire.

    Edit

  20. Pentax LX Main PCB Removal, Unsolder main PCB: step 19, image 1 of 3 Pentax LX Main PCB Removal, Unsolder main PCB: step 19, image 2 of 3 Pentax LX Main PCB Removal, Unsolder main PCB: step 19, image 3 of 3

    • Unsolder one light blue wire (may appear beige).

    • Unsolder one green wire.

    • Unsolder one pink wire.

    • Unsolder one blue wire.

    • Unsolder two black wires.

    • Unsolder one brown wire.

    Edit

  21. Pentax LX Main PCB Removal, Unsoldering: step 20, image 1 of 3 Pentax LX Main PCB Removal, Unsoldering: step 20, image 2 of 3 Pentax LX Main PCB Removal, Unsoldering: step 20, image 3 of 3

    • Unsolder one yellow wire.

    • Unsolder one white wire.

    • Unsolder one light blue/teal wire.

    • Unsolder one gray wire.

    Edit

  22. Pentax LX Main PCB Removal, Remove condenser lens: step 21, image 1 of 1

    • Remove four #00 1.8 mm screws.

    • Lift out bezel with glass attached.

    Edit

  23. Pentax LX Main PCB Removal, Lock viewfinder needle indicator: step 22, image 1 of 2 Pentax LX Main PCB Removal, Lock viewfinder needle indicator: step 22, image 2 of 2

    • Turn shutter speed selector to 'Auto'.

    • Turn lock lever screw clockwise to loosen. Do not remove.

    • Lock lever screw is reverse threaded.

    • Push lock lever toward the needle indicator gear.

    • Turn lock lever screw counter-clockwise to tighten.

    • Locking the needle indicator keeps it in the proper position once the mirror box is removed.

    Edit

  24. Pentax LX Main PCB Removal, Unscrew main PCB: step 23, image 1 of 3 Pentax LX Main PCB Removal, Unscrew main PCB: step 23, image 2 of 3 Pentax LX Main PCB Removal, Unscrew main PCB: step 23, image 3 of 3

    • Remove two #00 2.8 mm screws. Remove two loose spacers underneath the PCB.

    • Remove two #00 2.0 mm screws.

    • Remove two #00 2.0 mm screws.

    Edit

  25. Pentax LX Main PCB Removal, Remove mirror box: step 24, image 1 of 2 Pentax LX Main PCB Removal, Remove mirror box: step 24, image 2 of 2

    • Remove two #00 3.0 mm screws.

    • Remove one #00 5.0 mm screw.

    • Remove mirror box by lifting up then out. Pull slowly and check for snags as you remove.

    Edit

  26. Pentax LX Main PCB Removal, Installation Notes: Mirror box: step 25, image 1 of 2 Pentax LX Main PCB Removal, Installation Notes: Mirror box: step 25, image 2 of 2

    • Before installing the mirror box, the shutter should be wound and the mirror released into the taking position (up against the focusing screen).

    • After mounting the mirror box, make sure all necessary wires are available through the bottom of the camera for soldering.

    • Check for proper coupling of the self timer and the shutter button release.

    • Check that the closing curtain latch sits forward of the mirror return latch.

    • Check that the FP switch lever holds the magnet lever.

    • Select one of the mechanical shutter speeds and test the function of the mirror and shutter. The camera should be capable of a complete exposure cycle at this point.

    Edit

  27. Pentax LX Main PCB Removal, Unsolder main PCB: step 26, image 1 of 3 Pentax LX Main PCB Removal, Unsolder main PCB: step 26, image 2 of 3 Pentax LX Main PCB Removal, Unsolder main PCB: step 26, image 3 of 3

    • Unsolder one yellow wire.

    • Unsolder one brown wire.

    • Unsolder one blue wire.

    • Unsolder one gray wire.

    • Unsolder three flash sync connections along the top of the viewfinder.

    • Unsolder one red wire.

    Edit

  28. Pentax LX Main PCB Removal, Remove main PCB: step 27, image 1 of 3 Pentax LX Main PCB Removal, Remove main PCB: step 27, image 2 of 3 Pentax LX Main PCB Removal, Remove main PCB: step 27, image 3 of 3

    • Remove two 2.3 mm #00 screws holding the viewfinder LEDs. These will need to be properly aligned during reassembly.

    • Remove one 2.3 mm #00 screw.

    • Pull or pry off one 3.7 mm plastic retaining post.

    • Remove one 2.3 mm #00 screw.

    • Pull or pry off one 2.8 mm plastic retaining post.

    • Gently pull main PCB away from mirror box housing.

    Edit
Conclusion

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

Author

with 1 other contributor

Sam Gustafson

Member since: 09/01/22

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