Pentax LX repair & common faults
Excellent coverageThe Pentax LX was Pentax's professional-grade SLR, introduced in 1980 and built to run on batteries or without them. Exposure is set by a silicon photodiode reading light off the film plane itself during the exposure, a feature almost no other camera of its era attempted, while two mechanical speeds and bulb keep working with no power at all.
Aperture-priority auto exposure with off-the-film metering · Hybrid mechanical/electronic vertical metal shutter · SPD cell metering · 2 × SR44/LR44 (1.5 V) · Pentax K bayonet mount
Common Pentax LX faults
Pentax LX mirror bounces or blurs the shot
This is the LX's best known weak point. The foam damper that cushions the mirror as it swings up perishes with age, so the mirror keeps vibrating for a fraction of a second after it should have settled, softening the image at mid to fast speeds. It has nothing to do with the shutter or lens, and no amount of cleaning fixes it.
Pentax LX meter reading wrong or not responding
The LX meters directly off the film during the exposure rather than off a fixed cell, which makes its metering circuit more involved than most and more prone to drift or failure with age. Before anything else, fit two fresh SR44 or LR44 cells and check they're seated the right way round, as tired cells are the most common cause of a dead or wandering reading.
Pentax LX shutter won't fire
The LX runs electronically at most speeds but keeps 1/75, 1/2000 and bulb mechanical, so it will still fire without power at those settings. If it's dead across the board, suspect the battery contacts or the electronic shutter circuit; if it only fails on the auto and slower speeds but still fires mechanically, that points more specifically at the electronics.
Pentax LX viewfinder needle or LEDs dim or missing
The LX shows exposure information as an LED readout down the side of the finder rather than a needle. Faint, flickering or missing segments usually mean the display itself or its driving circuit has aged, not the metering cell behind it. Worth ruling out a weak battery first, as a low cell will dim the display before it affects anything else.
Pentax LX self-timer or mirror lock-up lever stiff
The lever on the front of the body drives both the self-timer and mirror lock-up through the same mechanical linkage. Stiffness, a lever that won't hold its position, or one that doesn't complete its swing points to old grease or wear inside that mechanism rather than anything electrical, and is usually independent of how the rest of the camera is performing.
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Try it now ›Scatto is a reference tool for people who service film cameras. It explains mechanisms and quotes service data, but it cannot see your camera at the bench, so verify anything load-bearing before you act on it.