When a cue is read, the "stepper" goes, "Chicka - chicka - chicka.....", all the way down the board and just keeps going. It keeps going 'round and 'round and never stops.

We changed out all the relays and no effect. Any ideas?

However, one of the last ones I saw was in Huntsville, Alabama in a 70mm house in late '60's. It worked most of the time. Maybe the newer models were ok, but I was not impressed with what I saw in the older models. The projectionist was complaining about it popping diodes on a regular basis.

And, from what Gordon is saying, it just seems like too many things can go wrong with them.

Unfortunately these days howerver, more and more, the job of programming is being left to staff who have neither the training nor inclination to put of a good presentation. They are usually satisfied if they manage to "get through a show" without too many refunds.

At a couple of theatres I visited, for example, they had the sound switching to Dolby 04 simultaneous with the projector motor starting, giving the audience the pleasure of hearing the leader and sync "beep" as it came up to speed.

Re: your intemittent problem with this automation, relay "C" as i recall, is responisible for the auto stepping function. If a shorted diode in row 15 is present, the thing will step forever.

Row 15, by the way is a good way of checking diodes. Simply fill up the row with diodes to be checked and pulse the board. It should continue merrily on its way around the 48 steps, continuoulsy. It it does, all diodes are at least, conducting. Remove one diode and the stepper should stop when it reaches this line. (Now you know that none of the diodes is shorted, either.) If it continues on, one of your diodes is shorted. (I have replaced the diode elements too, with 1N4004 diodes at a cost of about 14 cents each).

In one of the first installations of these boards, in Belleville Ontario, back in '68, the installation electrician failed to provide protection for the circuitry before drilling holes for elecrtical conduit into the top of the automation, resulting in many metal particles throughout the automation. This caused mysterious cues to appear during the show for years after.

Gordon brings up a good point about the blue Crouzet sensors. They are normally closed, meaning that the R-10 relay is normally energized until they see a pulse. They temporarily de-energize and the normally-closed contacts cause the board to pulse. If the sensor is going (good luck finding a new crouzet), or the relay contacts are badly worn, this will cause the stepping you describe.

The sensor can be changed to a normally open type, provided you change the pin connections on the R-10 to normally open. An addittional advantage of this is that the board will not step every time you turn it on.

The Philips/Norelco/Kinoton version was similar and was acknowedged as one of the best automations made.

Today the CA21 made by Pennywise and sold by Christie and Kinoton is essentially an electronic version of the old relay matrix boards of the Cinemation era.

The advantage of these matrix units is that you can see what has happened i.e. follow the trail and see what is coming up next.

For a photo see page 135 of your SMPTE Motion Picture Projection and Theatre Presentation Manual, 1969 version!

David