I have a problem with my Cp500. I noted that when I have a changeover from P2 to P1, CP500 stays in SR for few moments before going to digital. The problem is that this "moment" is between 1 second to 5 minutes...
I looked at the CP and I saw that when there is the c/o, CP switch from "P2" to "P1" but stays in "V2" for seconds.
Testing in manual, every time I close and open the dowser I have the same problem (the CP stays in V2 for few time).
I read Cp500 installation manual and I realized that digital sound has a different c/o pulse. I've opened the 9pin plug behind the CP and I found 2 cable with 2 wire coming from outside. I will search in the mess of cable where these cables are coming from but, in the meantime, do you have any suggestions? I didn't understand very well the meaning of the "motor start" pins. Can you explain me better?

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Yes, I supposed that the problem is a faulty microswitch. Unfortunately my tech is not so reliable (he told me to turn up the Digital red LED gain on the transformer despite I told him that on Cp500 there was the "V2" lighted).
I didn't understand very well the meaning of each pin in "Motor start" plug behind the Cp500. I saw two "motor start" for each projector, but what about the other pins?
I could check faster if I knew the meaning of these pins! Dolby manual is not very clear.

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Steve

Yesterday night made few tests. I followed all cables from CP500 to projectors and I discoveded the following:

1. I have one cable with two wires that is coming from projector 2. It is wired at the motor relay into the projector. However a piece of wire is locked between the two ends so that they are always shorted. These two cables end to pin 5 and 3 of "motor start" plug on CP500 (consideration: why Cinemeccanica put a cable between Dolby and Proj2 if it is shorted at its end???). I tried to open the circuit disconnecting one cable from the relais and I found that CP500 goes on "v2" or "v1" (depending if I short or open the circuit) after few seconds.
2. Other 2 cable are coming from the changeover relais (proj1 and proj2) and ends on Cp500 on pins 5 and 9. Pins 5 and 1 are shorted directly on the plug.
3. I've disassembled and cleaned both RCM (changeover relais) on projector 2 and 1 without results.
4. I connect a tester on wires coming from changeover circuit from P1 and P2 direclty behind the cp500: if dowser is closed the circuit is opened, is dowser is opened the circuit became shorted. Seems to works.
If the other two wires are shorted directly inside projector 2 where is the problem?

Could be a dolby problem?

However I still don't understand how the circuit works...

Thsnks for all your suggestions!

Richard,

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Pin 5 = common
Pin 3 = Projector 2 (must be a held contact)
Pin 1 = Motor 1 (must be a held contact while the motor is running)
Pin 9 = Motor 2 (as above)

You had stated that motor and projector relays were connected in reverse of the above.

Steve

I have the following situation:

Pin 3: held contact
Pin 1: connected with 5 (held contact)
Pin 9: connected with the changeover circuit. This circuit goes by RCM ("Change Machine" relais) of both projector and by CN2 (motor start) relais of projector 1.

My tests with tester indicate that this circuit is closed when projector 1 is not running and opened when dowser is opened (or vice-versa I do not remember now!).
Really, I didn't found any signal that tell to CP500 when motor 1 or motor 2 are running. I don't understand this.

But tell me: how can I manually test the Cp500 to see if the problem is in the CP or in the projectors? How can I manually connect cables to the "motor start" plug to simulate a changeover?

If I understand well I have to put a cable from 5 to 3 and then connect a cable from 5 to 1 and from 5 to 9 to simulate changeover. Is is right?

However, I still don't understand very well the mechanism...
Let's imagine the real situation: Cp500 is idle, with P2 and V2 selected.
Projector 1 starts. What should arrive to Cp500 "motor start" plug in this moment?

6/7 seconds later the dowser will open.
At this point "p2" became "p1" and "v2" became "v1".
What causes this?

At changeover I have a cue that cause the motor of M2 to start.
6/7 seconds later I have the changeover: the dowser of M1 close and the dowser of M2 open.
What causes this?

When proj2 stops, cp500 stays in "p2" "v2" but when motor starts again the cp500 goes to "p1" "v1" until proj2's dowser will opened.
What causes this?

Sorry for my questions but:

1. Until I don't understand very well the mechanism I cannot tests the circuit;
2. My tech is not useful at this time...

Thanks again!

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Thanks for your reply. I finally understood how the system should work. I didnt' understood it before because, as you noted, my system is wired in a different way!!
I undertstand now why "M1" and "M2" are always lighted on Cp500's display.
However, why the system has worked properly until few months ago?

I will try to set the changeover cables as you suggested. It is not difficult because there is a relays on motor relays that I can simply connect to motor start plug.

Thanks again!

You showed me a new world into my Cp500!!! Yesterday night I made few tests. I disconnected the held contact on motor start into proj. 2 and I realized that when that contact is closed the "m2" led on cp500 display blink for seven seconds and then goes to "v2".

However I have few question.

1. If CP500 should work as explained, why my two projectors has been wired as described?
2. If my current system is wrong why does it has worked perfectly since 1994 when projectors has been installed?
3. If I connect motor start relais as you showed to me, I have CP500 changing to V2 just when its motor is started. So if I'm making some manteinance to, for example, projector 1 and I decide to start the projector (with dowser down and lamp off) forward, after 7 seconds I'll have the digital sound of projector 1 in auditorium, isn't it?
I currently have the digital changeover when the changeover happen. So NO digital sound until dowser is not UP.

Thanks for help!

I made new tests and I would like to discuss with you.

Yesterday I remembered that once I already had problems with "v1" "v2" led few months ago. At that time I found a not used cable connected to "automation" plug that was picking up some interferences (i suppose) because I resolved the problem disconnecting that cable. I supposed interferences because that cable was 30 meters long (I build my own CP500 remote control bringing all SK cable to ticket office where I can control the projection).
During september, to avoid new interferences (sometimes adjusting frame caused the CP500 to change format) I put a relais' array so that from booth to ticket office I have +5V and the cable from Dolby to relais is reduced to minimum in the booth.
So yestarday night I tried to unplug the "automation" plug, but nothing changed.

However I found the following: I'm not sure, but when Proj 1 starts, and CP stays in analog sound, I can have digital sound pressing many times an SK with Digital sound.
For example: I have Dolby Digital with fader set at 4 on SK2 (trailers). When projector 1 starts, CP500 goes to SK2 and immediately to SK8 (Dolby SR). If I do nothing, it usually stays in SR for few minutes (also 5/6 minutes). But I found that if I start pressing SK2 button, usually CP goes in Digital after few seconds.
This is very strange and, if it is true, it indicates a fail into the CP500, isn't it?

Tell me: if I short pin 5,1 and 9 should V1 and V2 follow the P1 and P2 led?

Thanks for any kind of help!!!