Please show me your MX gearing

Beepaitch · 03-22-2022, 07:40 AM

Hello, I'm in the middle of trying to diagnose a problem with slow speed selection on a Pentax MX.
I posted yesterday about a DIY CLA but this is a bit of a tangent to please excuse the second post to try and keep the other one on-topic.

Using some rudimentary shutter speed measuring, I know that all speed settings slower than 1/60th also fire at 1/60th. I've seen others refer to "slow speed escapement" so guess there is an issue with this.

Here's a photo of my gear positions at 1 second:

The L-shaped item I've marked on there in RED stays in that position at all times. Having searched around for photos of MX's with their bums uncovered, most of them seem to show that L-shaped item in the position I've marked in GREEN.
It seems that the pawl-item marked with a BLUE dot never moves, even though it looks to me like the other end of it is radiused with teeth, so it looks like it should rotate at least 30º or so.

Can anyone tell me, or better still show me just when the L-shaped item should be in GREEN position? I.e at which speed settings. I'd like to compare and contrast and trying and work out what's not happening when I wind-on at slow speeds.

Besides this missing slow speeds problem the camera seems to fire ok after a clean yesterday.

Thanks!

**ismaelg** · 03-22-2022, 08:18 AM - **2 Likes**

Hello,

I serviced my MX as an adventure a while ago. I found this link very helpful. I don't understand the writing but the pictures are helpful.
Pentax MX disassembly

Thanks,
Ismael

Beepaitch · 03-22-2022, 03:03 PM

Originally posted by ismaelg

… I found this link very helpful. I don't understand the writing but the pictures are helpful.

Thanks a lot Ismael, yes that’s really helpful, and quite a lot of it can be translated via Google Translate

sevened · 04-04-2022, 12:37 PM - **1 Like**

I recently performed my own CLA on a Pentax MX and also had issues with the slow speed escarpment. My problem was that speeds using the escarpment would not fire the shutter. It turns out that a small grain of sand (and I mean tiny) was in the gears and stopped the escarpment from working.

The escarpment always moves at the same speed, but the shutter speed selector dictates where the escarpment starts from, adjusting the amount of time the shutter is open.

I found the best way to work with the escarpment is by taking it out of the camera.

03-22-2022, 07:40 AM	#1
Beepaitch Senior Member Join Date: Oct 2019 Location: Gloucestershire, UK Posts: 111	Please show me your MX gearing Hello, I'm in the middle of trying to diagnose a problem with slow speed selection on a Pentax MX. I posted yesterday about a DIY CLA but this is a bit of a tangent to please excuse the second post to try and keep the other one on-topic. Using some rudimentary shutter speed measuring, I know that all speed settings slower than 1/60th also fire at 1/60th. I've seen others refer to "slow speed escapement" so guess there is an issue with this. Here's a photo of my gear positions at 1 second: The L-shaped item I've marked on there in RED stays in that position at all times. Having searched around for photos of MX's with their bums uncovered, most of them seem to show that L-shaped item in the position I've marked in GREEN. It seems that the pawl-item marked with a BLUE dot never moves, even though it looks to me like the other end of it is radiused with teeth, so it looks like it should rotate at least 30º or so. Can anyone tell me, or better still show me just when the L-shaped item should be in GREEN position? I.e at which speed settings. I'd like to compare and contrast and trying and work out what's not happening when I wind-on at slow speeds. Besides this missing slow speeds problem the camera seems to fire ok after a clean yesterday. Thanks!

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03-22-2022, 08:18 AM - 2 Likes	#2
ismaelg Loyal Site Supporter Join Date: Apr 2009 Location: Puerto Rico Photos: Gallery Posts: 2,681	Hello, I serviced my MX as an adventure a while ago. I found this link very helpful. I don't understand the writing but the pictures are helpful. Pentax MX disassembly Thanks, Ismael

03-22-2022, 03:03 PM	#3
Beepaitch Senior Member Join Date: Oct 2019 Location: Gloucestershire, UK Posts: 111 Original Poster	Originally posted by ismaelg … I found this link very helpful. I don't understand the writing but the pictures are helpful. Thanks a lot Ismael, yes that’s really helpful, and quite a lot of it can be translated via Google Translate

04-04-2022, 12:37 PM - 1 Like	#4
sevened New Member Join Date: Jan 2022 Posts: 3	I recently performed my own CLA on a Pentax MX and also had issues with the slow speed escarpment. My problem was that speeds using the escarpment would not fire the shutter. It turns out that a small grain of sand (and I mean tiny) was in the gears and stopped the escarpment from working. The escarpment always moves at the same speed, but the shutter speed selector dictates where the escarpment starts from, adjusting the amount of time the shutter is open. I found the best way to work with the escarpment is by taking it out of the camera.