Pentax MX X-Sync Switch location

[MFstooges]

Does anybody know the actual location of Pentax MX X-Sync switch?
P/N 0-J621 from the exploded diagram it looks like facing down on the bottom?

But there's nothing that looks like it on the bottom

But there is this switch on the front

The switch on the front looks exactly like the replacement parts sold on auction site :

 

[cmacd123]

It should be closing about the time the first curtain reaches the end of its travel, if that helps.

 

[vandergus]

Yeah, that's it. It is triggered by the opening curtain wind gear, which sits directly above it. The wind gear spins as the opening curtain travels and when it reaches the end, a post closes the X-sync switch.

They just didn't have enough room to put it close to its installed location in the exploded diagram. There might be some dashed lines that didn't make it through the scanning process.

 

[MFstooges]

Yeah, that's it. It is triggered by the opening curtain wind gear, which sits directly above it. The wind gear spins as the opening curtain travels and when it reaches the end, a post closes the X-sync switch.

They just didn't have enough room to put it close to its installed location in the exploded diagram. There might be some dashed lines that didn't make it through the scanning process.

Just to confirm it closes to trigger? Do you know if there's a spec for the switch gap and if it can be cleaned without having to remove the self timer mechanism?

 

[vandergus]

Just to confirm it closes to trigger? Do you know if there's a spec for the switch gap and if it can be cleaned without having to remove the self timer mechanism?

Yeah, it closes the contact during an exposure. I don't see any spec for the gap in the service manual so you'll just have to test it with continuity. The contact should be open when the shutter is cocked and closed whenever the shutter has been released.

You might be able to clean it without removing the self timer, but it's really easy to remove. Just two screws and no alignment to worry about when you reinstall it.

 

[MFstooges]

I tried to remove the screw cover on the self timer lever but it won't budge even after heating it. It has tiny needle point indentation so someone must've removed it before.

 

[vandergus]

I tried to remove the screw cover on the self timer lever but it won't budge even after heating it. It has tiny needle point indentation so someone must've removed it before.

Yeah, that thing is a troublesome little bugger. I like to put a couple drops of isopropyl alcohol on it first and let it seap underneath the cap. There's some glue under there holding it on. Do this a few times. Then I take some masking tape and use it sticky side out to wiggle it loose. It usually comes off on the tape.

Edit: The other option is to only partially remove the leatherette. You peel it away from the body but leave it attached to the front plate. You also need to peel the corner just above the self timer lever to access one of the screws. Then you can remove the front plate without removing the self timer lever.

 

[MFstooges]

Yeah, that thing is a troublesome little bugger. I like to put a couple drops of isopropyl alcohol on it first and let it seap underneath the cap. There's some glue under there holding it on. Do this a few times. Then I take some masking tape and use it sticky side out to wiggle it loose. It usually comes off on the tape.

Edit: The other option is to only partially remove the leatherette. You peel it away from the body but leave it attached to the front plate. You also need to peel the corner just above the self timer lever to access one of the screws. Then you can remove the front plate without removing the self timer lever.

The cover still won't budge even after soak it with few drops of alcohol.
Are you sure it is not screwed all the way to the self timer mechanism? Then how does it engage with the mechanism? There seems to be two parts of front plates on the left side. Only one part is secured to the chassis with two screws and that's the one with self timer lever.

 

[vandergus]

The cover still won't budge even after soak it with few drops of alcohol.
Are you sure it is not screwed all the way to the self timer mechanism? Then how does it engage with the mechanism? There seems to be two parts of front plates on the left side. Only one part is secured to the chassis with two screws and that's the one with self timer lever.

The cover is just decorative and held on with a dab of glue. There's a screw underneath that holds the lever on. The lever sits on a keyed post that interacts and charges the mechanism in the camera body.

As you peel off the leatherette, you may see a metal cover lift off and stick to it. This is just an access cover that would allow a tech to get to the adjustment screws on the shutter release shaft without taking the front board off. They could adjust shutter button travel, for example. You can leave it stuck to the leatherette.

The two screws are what you're after. Once you've peeled the leatherette enough to access them, remove them and the left side of the front board will be free. Remove the leatherette from the right side and those two screws as well.

Underneath, there should be four shim washers. One at each of the screw locations. Keep track of which washer goes at which location. There are also two wires that connect to the aperture resistor. They will need to be unsoldered to completely remove the front board.

 

[MFstooges]

The two screws are what you're after. Once you've peeled the leatherette enough to access them, remove them and the left side of the front board will be free. Remove the leatherette from the right side and those two screws as well.

Someone else's photo here but these are the two screws, correct? And the access cover is removed.

The cover is just decorative and held on with a dab of glue. There's a screw underneath that holds the lever on. The lever sits on a keyed post that interacts and charges the mechanism in the camera body.

As you peel off the leatherette, you may see a metal cover lift off and stick to it. This is just an access cover that would allow a tech to get to the adjustment screws on the shutter release shaft without taking the front board off. They could adjust shutter button travel, for example. You can leave it stuck to the leatherette.

The two screws are what you're after. Once you've peeled the leatherette enough to access them, remove them and the left side of the front board will be free. Remove the leatherette from the right side and those two screws as well.

Underneath, there should be four shim washers. One at each of the screw locations. Keep track of which washer goes at which location. There are also two wires that connect to the aperture resistor. They will need to be unsoldered to completely remove the front board.

This is also pic from someone else which shows the four washers that you mentioned on A & B.
My question : is the lever screwed to the hole pointed by red arrow? If the lever is screwed to the hole it means that I have to unscrew the self timer lever to remove the front plate, no?
The post on green arrow seems to activate the self timer.

 

[vandergus]

Someone else's photo here but these are the two screws, correct? And the access cover is removed.

Correct.

My question : is the lever screwed to the hole pointed by red arrow? If the lever is screwed to the hole it means that I have to unscrew the self timer lever to remove the front plate, no?
The post on green arrow seems to activate the self timer.

No, it doesn't screw into that hole. The lever mechanism just pushes on the post indicated by the green arrow. It will simply lift away from it.

 

[MFstooges]

I got to the two screws and can lift the stainless access cover but the front plate still can't be lifted. This is with the self timer lever on the resting position. Seems like there was some linkage behind the front plate that was obstructing the removal.

 

[vandergus]

I got to the two screws and can lift the stainless access cover but the front plate still can't be lifted. This is with the self timer lever on the resting position. Seems like there was some linkage behind the front plate that was obstructing the removal.

Did you unscrew the other side of the plate as well? Otherwise, there might be some glue down in the cracks keeping things together.

 

[MFstooges]

Did you unscrew the other side of the plate as well? Otherwise, there might be some glue down in the cracks keeping things together.

I have not retried yet but you may be right, someone may have put glue to attach the plate. I just noticed the self timer also won't stay cocked. May be I will try to put some alcohol to soften the glue.

 

[MFstooges]

I finally had time to work on the camera. The X sync port and hot shoe are now working but the self timer still won't stay cocked past 90 degree travel of the lever.