Film-Tech Forum ARCHIVE: CP 650 sound problem

This is topic CP 650 sound problem in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bernhard Benet (Member # 2976) on 08-01-2006, 08:33 PM:

After working fine for 6 months all of a sudden I no longer have analog sound. SRD continues to work as before. All I hear is a little buzzing and clicking when I play an analog soundtrack. Other sources such as external input and NS input work OK.

Bypass doesn't work either. I tried projector 2 and it doesn't work either.

Level still shows 40 for L and 48 for R. Soundhead works fine, red beam is right on target. Only has about 200 hours. Any idea where the fault may be?

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Posted by Steve Guttag (Member # 268) on 08-01-2006, 09:07 PM:

Hmmm...projector #2 is no go either you say...do you have a 2-projector set up or did you just switch to the proj 2 input and tell the CP650 to go to projector 2?

Lets say you just have one projector...I would look at the power supply for your reader there is a bi-polar supply that feeds a 3-pin connector on the reader board somewhere (you did not denote the reader type...if you had a BACP it would have status LEDs on it so I'll presume it is a CE or Kelmar). If you only lost one channel, I would suspect cell wiring but to loose both channels...definately looks like it is in the pre-preamp supply...make sure all three wires are connected (+, - and Ground) and the connector is pushed in properly.

Alternately...it could be that the LED got "bonked" and is not sitting too low or too high...you will NOT be able to see that by eye...it has a VERY narrow sweet spot.

Steve

Posted by Bernhard Benet (Member # 2976) on 08-01-2006, 09:52 PM:

I have a one projector setup. I only switched the cable to projector 2 input to find out if I can get sound which I didn't. All the cables are connected and tight. Everything had been working fine for a few months.

I forgot to mention that there had been a very bad storm prior to the problem occuring which killed some other electronics. I am wondering if a lightnigh strike might have disabled the analot optical input somehow. Otherwise the 650 appears to be normal and will also boot up normal.

I also suspected the soundhead and took a high resolution picture and sent it to the manufacturer's service engineer. He looked at it and told me the beam looks as it should. The sound head is made by Ernemann (Germany) and is supposed to be very robust.

Also wouldn't an interruption in the power supply of the reader cause the light not to work?

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Posted by Josh Jones (Member # 447) on 08-02-2006, 01:40 AM:

Sounds like you lost the front end of your optical preamp. Are the levels your referring to the optical decode levels or what?

I must admit I'm not terribly up on my 650's, But will do what I can.

JJ

Posted by Bernhard Benet (Member # 2976) on 08-02-2006, 07:09 AM:

I was refering to the Left Level and Right Level Adjustment in the 650 menu. It still gives me the numbers that auto level set it to. The actual level bars on the front do not show up when the film is running.

Loss of the front end of the optical preamp would be a 650 issue, correct?

Also according to the soundhead manufacturer there is no pre-pre amp on the soundhead, the signal goes directly to the processor.

Thanks
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Posted by Michael Schaffer (Member # 1204) on 08-02-2006, 08:56 AM:

Is that one of Ernemann's Laser Audio analog/digital combo thingies?

Although this has been mentioned by Steve, you didn't specifically say that you actually switched the CP650 to projector 2. Did you jumper pins 3 and 5 on the motor start connector and made sure the P2 indicator just above the fader was lit? Then you also may have to perform level setting because it could be all the way down. You normally don't have to actually switch over the CP650 to set the level on P2, and since you said you checked the level, it is likely that is not the problem. However, I wanted to doublecheck because sometimes it are really easy things which are simply overlooked in the heat of battle.

Posted by Bernhard Benet (Member # 2976) on 08-02-2006, 09:22 AM:

Hi Michael

Yes it's one of ernemann's combo laser analog/digital thingies. It's only a few months old, less than 150 hours on it.

When I tried projector 2 I only switched dip switch 1 from down to up. This dip switch is located on the front panel behind the cover. I then powered the 650 down and up and it enabled projector 2. I didn't realize I also need to switch jumper pins 2 and 5 on motor start. Where are those jumpers located?

Thanks
Bernhard

Posted by Michael Schaffer (Member # 1204) on 08-02-2006, 09:40 AM:

The dip switch to set the wakeup projector is another variation. If you already did that then changing over won't be necessary. There are several variations. They are all described in the backplane connector diagram which you can download here. But what you did also works, as long as the P2 indicator comes on.
It has been a while since I played with one of the Ernemann thingies, but IIRC, they only have one double bundled cable for analog and digital and that plugs in somewhere in the projector head. There has to be a terminal strip or connector somewhere in the head where that hooks up to the cabling that then goes to the CP650. Since the Dolby tone is a sine wave, you can measure it with a regular multimeter and follow the signal from the sound head to the processor or the other way around and see where it disappears. I don't remember in what level range the signal typically is before the optical preamp, but I am sure Steve will know that off the top of his head. Basically all our machines have the BACP or the Kinoton readers and there are so very few problems with those I haven't done that kind of troubleshooting in a while.

Posted by Sam D. Chavez (Member # 1841) on 08-02-2006, 10:21 AM:

This projector usually comes equipped with a laser reader for analog. It's not mine since I don't make a reader for this model projector.

Posted by Bernhard Benet (Member # 2976) on 08-02-2006, 10:30 AM:

My soundhead actually has 2 cables one going to the analog input and one going to the digital input. As I mentioned the digital path works fine. I am having a sound engineer come in to try to measure where the signal ends. I just tried doing an autolevel using a 69T test flm loop, but the response I got was "out of range?" so obviously the 650 is not getting any kind of signal or the signal is blocked due to a malfunction in the optical preamp.

I also posted the problem on the german film handler's forum and was told that the ernemann heads are very robust as well and don't cause any problems. Ernemann has a large market share in Germany.

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Posted by Richard Fowler (Member # 893) on 08-02-2006, 10:34 AM:

Since you live in one of the most lightning prone places in the world; surge and filtering on the CP650 and pre-amp card in the Ernemann circuit box could use protection. Most Ernemann 15 have the analog sound output on the far right of the terminal strip in which can be a test point that signal is coming from the projector.

Posted by Bernhard Benet (Member # 2976) on 08-02-2006, 11:35 AM:

I think if I read your comment correctly you are saying that the cable may have gone defective?

I had also been thinking that this is the case but the Ernemann tech familiar with the soundheads told me that if that happened it would have only happened to one channel and I would still get the other channel. He can't see that happen to both channels.

I was also told that there is no optical preamp card in the ernemann.

BUt then again, couldn't a lightning strike kill the solder points of the cable?

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Posted by Bernhard Benet (Member # 2976) on 08-03-2006, 12:15 PM:

Problem solved. Dolby sent me a new 650 and it works fine. Obviously the problem was in the processor.

Thanks for everyone's advise. This is the first time I posted here but this board is a great resource and through this problem I was able to find a local service tech I can contact in an emergency.

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