Introdução
The shutter speed resistor is a common point of failure in the Pentax LX. The component consists of a pair of feeler contacts sliding along a carbon filament. The resistance value created by this assembly communicates the selected shutter speed to the camera. Over time the contacts can become oxidized and/or dirty resulting in erratic behavior when using the manual electronic shutter speeds. Cleaning the resistor can restore the camera to normal functionality.
Any disassembly of the LX body will compromise the weather sealing. New seals must be reapplied during final reassembly to restore weather proofing.
Ferramentas
-
-
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.
-
-
-
Gently remove the rubber covering around the shutter speed dial.
-
Remove three #000 1.6 mm screws.
-
Remove cover ring.
-
-
-
Unhook lever spring.
-
Remove slotted nut. Use isopropyl alcohol to soften thread lock if necessary.
-
Remove all components of the timing switch assembly.
-
-
-
Turn shutter speed selector to 'Auto'.
-
Turn lock lever screw clockwise to loosen. Do not remove.
-
Push lock lever toward the needle indicator gear.
-
Turn lock lever screw counter-clockwise to tighten.
-
-
-
Unsolder two yellow wires.
-
Remove one #00 4.0 mm screw.
-
Remove one #00 2.2 mm screw.
-
Remove one #00 2.5 mm screw.
-
Remove high speed cam.
-
-
-
Rotate the speed dial until the feeler contacts are visible in the gap.
-
Spray with a plastic safe contact cleaner and rotate back and forth.
-
Check the resistor values at the slow speed settings. They should range from around 9 kΩ (at 60) to 200 kΩ (at 4s) with no dead spots.
-
Clean the seat for the high speed cam with isopropyl alcohol. A narrow cotton bud or a floss pick work well.
-
Lubricate the high speed cam seat with shutter oil.
-
To reassemble your device, follow these instructions in reverse order.
6 comentários
Hello everyone. I have an LX that initially couldn't lower the mirror or release the second shutter curtain. It turned out to be a broken speed sensor wire within the mirror box mechanism. After that, I removed and cleaned the speed potentiometer, and now the shutter only operates at one speed. Any suggestions on how to fix this?
Just to clarify, you're saying as you change the shutter speed dial to different settings, it keeps firing at the same speed? If that is the case, my guess would be a short around the speed selector assembly. If the camera sees 0 Ohms at he speed selector, it would be stuck in a single speed. I would double check your soldering and check the resistance at the point where the yellow wires connect if your have a DMM.
That's right. I changed the speed dial, but the shutter speed didn't change. Today, I measured the resistance value, and it still gave different values at each speed. However, the shutter speed still didn't change. I suspect it's either stuck or I've incorrectly assembled the speed cam. I'm currently unsure which part of the mechanism it is. Thank you for your response
I cleaned the resistor. However after doing this I have two problems :
1. I am not sure how to put back high speed cam.
2. When I loosened the needle indicator screw and now I cannot adjust it properly. It seems that whenever I turn the speed selector it moves the needle half way.
Can you please help me.
1. The high speed cam just kind of sits on top of the wind gears. The only thing to note, which isn't shown very well in the photos, is to make sure the small peg on the wind gear sits in the slot of the high speed cam.
2. Sounds like the gear on the speed selector assembly is not meshing properly with the gear driving the viewfinder display. I would just try removing and reassembling.