Pentax MX Viewfinder Speed Indication Adjustment

Remove the lever cap. The cap is reverse threaded.

Lift off the advance lever.

Remove the collar beneath the lever.

Set the ISO to 100 and the shutter speed to 1000.

Remove one pin head screw.

Lift off shutter speed dial.

Remove the collar beneath the dial.

Installation Notes: Make sure that the tab on the shutter speed resistor mates properly with this slot on the shutter speed dial.

Place a tool in the fork of the rewind shaft. Turn the rewind knob counterclockwise to loosen it.

Remove the lock ring underneath the rewind knob.

Remove the cover plate.

Remove two M1.7 x 3.2 mm screws.

Remove two M1.7 x 2 mm countersunk screws.

Lift off top cover.

The release cable pin in the shutter button is loose and may fall out.

Remove one M1.3 x 2.8 mm screw and washer.

Remove one M1.7 x 2.8 mm screw.

Pull the LED PCB out of the side of the mirror box.

Temporarily install the shutter speed dial.

Set the shutter speed to '1000'.

It can be helpful to tape the LED board out of the way while you work on the adjustment screws.

Loosen but do not remove the slotted post.

Shift the idler gear so that it doesn't engage with the gear attached to the speed display.

Move the disc until '1000' is displayed roughly between the two points on the edge of the frame.

Move the idler gear back into position so that it meshes with the gear attached to the speed display.

If the speed display does not move smoothly in both directions when the shutter dial is turned, adjust the eccentric until the gears mesh properly.

Tighten the lock screw.

Loosen the lock screw on the adjustment pulley. This screw is reverse threaded.

Turn the eccentric adjustment until '1000' is perfectly horizontal in the viewfinder.

Tighten the lock screw on the adjustment pulley.

Check the position of the indicators throughout the range of speeds. Repeat adjustment as necessary.

Loosen two screws.

Move the support plate up or down to center the number vertically.