Mirror stuck is a common problem of old Pentax 6X7/67 cameras when their mirror gets stuck in upper position after the shutter has fired and remained open. There are several reasons for the mirror to lock up all the way with the shutter open, but the most common one has to do with the shutter holding magnet. The core of the magnet gets magnetized and stops releasing the second curtain. Usually cleaning the magnet and electrical contacts solve the problem. So, let’s begin the repairs.
Attention! Do not attempt to repair your camera until you read this article till the end! Well, to get access to the magnet and electrical contacts, you need to remove a few covers from the camera body. First, you need to take out leatherette finishing which covers the screws. Next, let’s see a disassembling scheme on how to remove the covers. You can find it on page 96 of the Pentax 6X7 Service Manual. See the image below for the details. I marked in red the parts that should be removed.
The original service manual available on the web is for earlier versions of the Pentax 6X7 camera with no mirror lockup unit. But the disassembling of Pentax 6X7 and 67 cameras do not differ significantly. However, there are some very important points.
- Note a screw highlighted with the green arrow. The former is not shown in the manual but is present in actual cameras. I’ve included it in the scheme.
- Screws highlighted with the red crosses should not be unscrewed. One of these screws fixes the spring of MLU lever. This spring prevents the lever from dangling. See the image below for the details — this screw should not be unscrewed!
Ok, now you have access to the magnet and other electrical contacts. See the image below. The areas marked with the red arrows should be cleaned with special liquid electrical contact cleaner or absolute ethanol. To clean the magnet (marked with the left red arrow) you should cock the shutter, then take out the battery and press the shutter release button. The mirror will get raised by a half, releasing the lever above the magnet. This will allow you to clean this spot well. CAUTION! Do not spray cleaner directly on the contacts. Pour some liquid on a thin cotton swab instead and clean the contacts.
Now the cleaning is done. It’s time to check the camera. If the problem appeared during shooting on slow shutter speeds, then start testing it on the fastest shutter speeds and vice versa. Watch this video for more details of the process. Do not forget to select HD quality of the video.
In its operating manual Asahi recommends checking a camera’s performance at least once a year to maintain it in a good working condition. In my practice, it should be checked more often and it rather depends on a camera’s condition.
For instance, I had a camera body which was heavily used by its previous owner, and its mirror got stuck every time it had not been in use for two months or even less. However, I’ve noticed that “dry fire” helps to extend the period until the next mirror stuck.
I think the dirt resulting from gear friction near the magnet sticks to it tightly when a camera is not in use for a certain period of time. And the older your camera gets, the shorter this period becomes. Eventually, I disassembled my camera body and successfully repaired it. This experience enabled me to write this article. So, I think that it is a good practice to carry out a “dry fire” series if you don’t use your camera for at least two months.
Ok, I hope that now your camera is again up and running! If not, there is one more trick which may be of help. When I started researching the web about this issue, I discovered that cleaning the contacts under the shutter speed dial could fix the problem for some people. Frankly speaking, it did not help me at all. Maybe, it works only for certain shutter speeds. But why not try it if the solution in this article did not help you. Good luck and keep snapping!