Pentax MX shutter sticking on Slower Speeds

[CaCtus_SaNdwich]

Hi All

I'm looking for some CLA advice for a Pentax MX I've picked up.

The shutter is sticking on slower speeds 1/30th - B and doesn't budge at all, keeping the curtain open and the mirror up only when turned to a speed over 1/30th and re-cocked the shutter closes and the mirror drops down.

I've taken the bottom off to have a look and from I can see the slow shutter assembly seems to be jammed and is holding the shutter open.

I've attached a photo, part B which I've marked I'm guessing adds some resistance to part A to get the desired shutter speed.

Any suggestions of points to clean / re-lubricate would be appreciated, I've attached another photo to annotate points.

Many Thanks

 

[dynachrome]

I would send the camera to Eric Hendrickson. If my memory is correct on this, the MX came out in 1977. That's a long time ago. I have at least three MX cameras. They are generally reliable but do need service sometimes. The weak point is that the LEDs get dimmer over time. I don't know if there is a cure for that. My KM cameras have probably seen more use. I have not had much luck using different focusing screens with the MX. Since I don't have an LX, if I want to use different focusing screens, I am more likely to use a Canon F-1 or a Nikon F2. With what film costs today, if I know I will want to use a camera with any frequency, I would rather get it serviced by a good repairman person.

 

[runswithsizzers]

I would send the camera to Eric Hendrickson. If my memory is correct on this, the MX came out in 1977. That's a long time ago. I have at least three MX cameras. They are generally reliable but do need service sometimes. The weak point is that the LEDs get dimmer over time. I don't know if there is a cure for that. My KM cameras have probably seen more use. I have not had much luck using different focusing screens with the MX. Since I don't have an LX, if I want to use different focusing screens, I am more likely to use a Canon F-1 or a Nikon F2. With what film costs today, if I know I will want to use a camera with any frequency, I would rather get it serviced by a good repairman person.

That is very good advice for Pentax MX owners in the USA, but acording to his website, I'm afraid Eric Hendrickson does not accept international repairs:

Home-Pentaxs

pentaxs.com

 

[hospadar]

Have you tried gently flushing out the moving parts with solvent (naptha or alcohol - naptha is more aggressive)? I recently picked up an MX body that was not always fully closing the second curtain, I took off the top and bottom cover and gave it a little naptha while working the shutter (many times) until things started moving more smoothly, then a VERY conservative amount of oil (I use a blend of 50/50 naptha/nyoil in a syringe, any clear fully synthetic machine oil is probably OK - synthetic sewing machine or gun oil for example).

Starting with just the solvent will give you a good idea if it's just a sticky-old-parts problem or if there's something more going on (bent cam, broken something, etc). Before it dries, the naptha will temporarily lubricate things and you may find that everything jumps back to pretty normal operation.

Generally, when applying solvent, keep the camera vertical or upside-down and don't go crazy with it, you want to avoid solvent dripping down into the curtains or carrying old grease deeper into the body.

 

[CaCtus_SaNdwich]

Thanks for your suggestions, I managed to get it running. I was a bit concerned about how seized up everything was and wanted to get things moving slightly before going in with the lighter fluid to clean off the old grease.

I've attached photos, using a wooden toothpick I located the escapement wheel (see example silver with triangle teeth) sandwiched in the slow mechanism located roughly where the magenta circle is in the photo, this freed everything up to where I could move the pin in blue and apply lighter fluid to clear it all out. I then applied small amounts of sewing machine oil at the pivot points. Cheers George

 

[hospadar]

Awesome glad to hear it!