jon_shumpert2 Posted December 31, 2014 Share Posted December 31, 2014 <p>I have a Pentax MX with an unusual problem. The camera will not trigger the shoe mount flash at shutter speeds of 1/60th or slower, but will for higher speeds. I know the obvious answer is to send it out for repair, but wanted to check to see if anyone else has encountered this problem. This is the second MX I have owned that had this problem. Any clues what the problem could be? For those who like photos of the classic manual cameras, here it is. I have a new (to me) 35-70 f/3.5-4.5 macro zoom on it that I got earlier today. I have had a 50mm f/1.7 on it so I thought I might shoot a roll with the new lens.</p><div></div> Link to comment Share on other sites More sharing options...
jon_shumpert2 Posted December 31, 2014 Author Share Posted December 31, 2014 <p>Here is one more photo of it. I need to clean it a little. Does anyone here have the 35-70 lens that I have on the camera. How does it perform? I guess I will find out for myself tomorrow.</p><div></div> Link to comment Share on other sites More sharing options...
john_shriver Posted January 1, 2015 Share Posted January 1, 2015 <p>Sounds like the X-sync contact is dirty inside the camera, or the switch between FP and X-sync. Flash sync happens at a very different time for FP-sync and X-sync. For FP, it has to happen before the shutter curtains start to open, so the flash bulb can get hot before the shutter opens. For X, it has to happen once the first curtain is fully open.<br> The MX service manual can be <a href="http://www.pentax-manuals.com/manuals/service/mx_sm.pdf">found free online</a>. There's a schematic, but it's not that well-done. O-J621 is the X-sync contact. But the FP-sync contact isn't labeled, but I guess it's O-J531. I don't see an obvious switch, maybe the shutter mechanism only closes the right one at the right speeds?</p> Link to comment Share on other sites More sharing options...
john_shriver Posted January 1, 2015 Share Posted January 1, 2015 <p>Do ring out the wires with an ohmmeter. Cameras often have so-so soldering, or use acid fluxes to solder to steel switches that later corrodes the wires.</p> Link to comment Share on other sites More sharing options...
John Seaman Posted January 1, 2015 Share Posted January 1, 2015 <p>The MX has separate sockets for X and FP, not a switch.</p> <p>I tried a flashgun on mine and it worked fine at all speeds. It may be worth trying a different flashgun, perhaps with a higher synch voltage to help break down any high resistance in the contacts. Also try a wired flash connection to either flash socket, this may just narrow things down.</p> Link to comment Share on other sites More sharing options...
bebu_lamar Posted January 3, 2015 Share Posted January 3, 2015 <p>I had an MX which I paid only $5 for at the garage sale. It was in excellent condition with the 50mm f/1.4 lens. The shutter was accurate, the meter was accurate, the view finder clean. I love the thing only to discover that it won't do the X sync at all whether on the hot shoe or at the PC connector. It does do the FP sync though. <br> I had to get rid of it.</p> Link to comment Share on other sites More sharing options...
andrewg_ny Posted January 25, 2015 Share Posted January 25, 2015 <p>For what it's worth, I tried a AF-360FGZ on one of my MX bodies, it fired fine at 1/4, 1/60, and 1/1000.</p> Link to comment Share on other sites More sharing options...
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