Film-Tech Forum ARCHIVE: Kinoton FP30D changeover

This is topic Kinoton FP30D changeover in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Richard May (Member # 2627) on 06-29-2017, 09:25 AM:

I have 2 Kinoton FP30D's here running changeovers. I'm wondering if something is wired wrong. We have a CP650 with Dolby Digital. Everything works fine when motors are running. If I want to start the film on projector one, I can't get the audio changeover to stay in P2. It only stays in P2 if the motor on P2 is running. When motors aren't running and I press changeover on P2, Dolby goes to P2 until I let go of button. It then goes right back to P1.

Posted by Steve Guttag (Member # 268) on 06-29-2017, 09:40 AM:

It all depends on how things are wired up!

The DA20 (and consequently a CP650) will "look" at the motor sense lines while running Dolby digital. If only one is active, the changeover will go to the active one, regardless of where the actual changeover line is set. Now, when you make a changeover, It will see the incoming motor come on and when you make the actual changeover, will switch the sound. But if you only have one motor running, the Dolby Digital part will automatically switch to that machine.

Since it is a CP650, you also have choices in how you connected your audio changeover to it (latched or pulsed). Many Kinoton installations use a spare contact on the #2 changeover relay to latch a processor to projector #2 while the douser is open and this would explain why the processor only switches for while you are holding the button down (if the motor/failsafes are not satisfied). I've never been a big fan of this method but it is the easiest to do. We ended up making a board that would allow us to track motor start, douser open, douser close button presses to switch the changeover logic to the cinema processor. It is more work but but the end result is the cinema processor is always looking at the right machine and it will also avoid hearing run-up noises (which is why we also monitor the motor start button).

Posted by Richard May (Member # 2627) on 07-08-2017, 09:50 AM:

Thanks Steve. I guess I'll leave it that way for now. I've been starting on projector 2 to avoid the leader sound on start up.

Posted by Dave Macaulay (Member # 813) on 07-08-2017, 02:14 PM:

We would wire a cheap relay's coil to the motors power inputs for Dolby "motor run" closures. With projectors using self holding changeovers, a toggle relay was used - one coil to close, another to release. Expensive relays but this was reliable and the operation was hopefully obvious to any future service person.