Film-Tech Forum ARCHIVE: Need some help - Simplex XLs Ghosting on Changeover

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Posted by Dave Carr (Member # 5566) on 03-10-2010, 07:22 AM:

Greetings, I am running dual 1950's Simplex XLs with the simplex changeover SA-5 I believe. As of late I am getting a brief ghost image when changing over and sometimes I have to double or triple clutch the pedal to complete the process; doesn't make for a very good show. I am pretty sure the issue is one or both of the dousers is sticking so the process isn't smooth. Our maintenance folks have been out 4 times so far and can't seem to fix this. Does anyone have any suggestions? Is there a way I can lubricate the douser cable?

Also, can anyone explain how the sound changes over with this system? Is it mechanical or electrical, and is it dependant on the dousers movement to complete the process? My audio has been "reverted" briefly on changeover also.

Thanks for any advice or help.

Dave

[ 03-10-2010, 08:36 PM: Message edited by: Mike Olpin ]

Posted by Joe Redifer (Member # 3) on 03-10-2010, 08:31 AM:

I have had this problem. If I held the switch long enough it would usually pop open all the way by itself, but sometimes it would need to be manually pushed the rest of the way open. I ended up changing out the whole changeover with a Kelmar unit. I still have one Simplex changeover in action that works fine, though.

The audio is independent of anything the changeovers are actually doing. Once you tell it to do the changeover, the audio should switch fine as it has no idea if your changeovers are working fine or not. It is a simple electrical pulse. As for your reversion, if you are running Dolby Digital, then the audio can revert to analog momentarily if you did the changeover at the wrong place. If it is switching back to the wrong projector momentarily, then you have some problems with your wiring or similar (sticking relays?)

Posted by Robert Throop (Member # 61) on 03-10-2010, 09:46 AM:

Is this a U.S. military installation? If so the one booth I'm familiar with uses Weaver changeovers. There is a microswitch on each changeover but only one is used. This switches between proj.1 and 2 on a Dolby CP65. Hope this helps.
Bob

Posted by Brad Miller (Member # 2) on 03-10-2010, 11:12 AM:

Dave, please read the rules and fix your topic. Since you are new we will give you 48 hours before closing this thread.

Posted by Monte L Fullmer (Member # 2797) on 03-10-2010, 12:52 PM:

Ya..little help: change your topic header to something more definite, like "brief ghost image when doing changeovers", or similar...

You can get away with teaser topics in other kinds of forums, but here, we need something more definite.

Posted by Tony Bandiera Jr (Member # 2365) on 03-10-2010, 01:35 PM:

Dave, fix the teaser please before this gets shut down!!

Robert, I'm willing to bet based on his location it is indeed military.

My old base theatre had a latching relay for the sound changeover, but based on Dave's description he has the microswitch on the dowser.

Those old style dowsers are a pain in the ass when they start to get sticky. Lubing the cable IS NOT gonna fix it!!

First thing I would try is to loosen the cable from the dowser pivot, remove the tension ball and spring from the top of the assembly, remove the small knob (and nut if present) from the guide rod and pull the cable and armature (or core if you prefer) assembly completely out of the unit.

Clean the armature (core) assembly with WD-40, wipe it dry. Use long cotton swabs to clean out the inside of the coil assembly (DO NOT EVER lube or spray ANYTHING into that coil assembly or you will be sorry), repeating till the swabs come out clean. You can, for the first few swabs wet them with WD-40 without causing harm.

If that doesn't work, then replace the whole dowser assembly with a Kelmar as Joe suggested. Because the next likely cause of the sticking is the guide pipe is bent and it is almost impossible to get it bent right again.