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09-28-2018, 04:28 AM   #1
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Jean Poitiers's Avatar

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Problem with a MZ-3 ... DoF button

Purchased this from a Japanese eBayer, but the shutter and all buttons "lock up" after the DoF is activated ... there's a slight "buzzing" sound when the shutter button or anything else is touched. I got it to "reset" once by fiddling with the batteries ... but locked up again as soon as touching the DoF button.

Anyone got some advice ... it's more than likely going back. Return procedure has been started ... darn.

09-28-2018, 05:15 AM - 1 Like   #2
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Not familiar with that particular model, but with a lot of these MZ cameras the aperture lever is actuated by a plastic gear (great idea right) that gets brittle and strips out over time. That's likely what's happened to yours. Definitely return it. If you're serious about film, get an MZ-S or PZ-1, or a manual focus model like the MX or KX.

The MZ-7 is a decent camera, but will likely eventually suffer the same fate as this MZ-3.
09-28-2018, 05:17 AM - 1 Like   #3
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The DoF button actuates the aperture mechanism. Perhaps some part of the electronics or the mechanism has failed. You want look closely at the aperute actuator for any kinds of damage. But before you cry "dreaded aperture block failure," see if it works with a different lens. It's a long-shot but perhaps a stiff aperture lever on one particular lens is blocking the DoF/aperture cycle from completing properly. If it happens with more than one lens, then it's probably a fault with the camera.

Good luck!

(P.S. I must admit I live vicariously through your marvelous acquisitions. )
09-28-2018, 05:28 AM - 1 Like   #4
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Sounds like it is related to the mirror lockup problem caused by the plastic pinion gear on the mirror motor. The buzzing sound is the motor running but since the gear is slipping the mechanical actions do not take effect. This seems to be a common problem with the MZ series. Exactly what functions get locked depends on at what state the mechanisms were when the gear began to slip.

The replacement motor from Pentax had a brass gear. The low failure rate of the MZ-S lead to speculation that these came equipped with the metal gear, but this may not be the case. See below. Stocks of the replacement motor, at least in the US, seems to have dried up. You can buy a replacement gear but you would need to either replace it yourself or find a technician who will do the repair.

kkpmo - Zahnrad / Trieb M0.25 / 13 Zhne
change the drill hole to 1.5mm, the width to 2mm and material to brass. Unless you know someone that can cut gears to specifications.

Refer to these threads (there are others but these I have bookmarked):
MZ5n mirror blocked, service manual? -
MZ-50 motor -
My old-New MZ-S After Returning From Repair -


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