Film-Tech Forum ARCHIVE: Cable to connect C.E. Reader to CSP1200

This is topic Cable to connect C.E. Reader to CSP1200 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Ian Bailey (Member # 1752) on 09-30-2005, 07:58 AM:

What is the best cable to use to connect a Component Engineering red led reader to the input of a CSP1200 processor.
Is it best to use crimped connectors on the end of the cables which go into the screw terminals or just solder the wires before terminating?
Is the shield connected at both ends?

Posted by Aaron Sisemore (Member # 145) on 09-30-2005, 02:35 PM:

I always solder everything, less possibility of a noisy connection in the future.

Both CE and BACP say in the instllation manuals to connect the shield at both ends for proper operation.

-Aaron

Posted by Gordon McLeod (Member # 33) on 10-01-2005, 01:55 PM:

I use belden 9451 the most 9452 in noisy enviroments

Posted by Ian Bailey (Member # 1752) on 10-02-2005, 07:01 AM:

Thanks guys.
I'd assume that it is best to run the cable with no joins anywhere? Why I'm asking that is because I have developed a slight hum in one auditorium(only in analogue sound)-the hum stops if you block the red led with a business card.I traced the path of the cable and found 4 places where the cable was joined at terminal blocks and even one twist join.I want to connect a whole new piece of cable to prove where the fault is.

Posted by Steve Guttag (Member # 268) on 10-02-2005, 08:46 AM:

If the hum stops when you block the LED...then it is not in the CSP1200 or your wiring...it is in the LED power supply or stray light or the reader itself.

If you have the hum with the film out of the projector but LED lit, change your LED supply...if you need to have film running in your projector for the hum, I would ask if you have a digital system basement reader in there too...if so, then odds are the digital LED is causing the perforations to refract the light back onto the optical pick up...Kelmar has this problem and include a light shield for their optical reader to prevent this.

Posted by Ron Yost (Member # 1850) on 10-02-2005, 01:58 PM:

Try running a short wire to connect the reader ground with the projector/sound head frame. I ran a wire to one of the screws that had held the original exciter assembly. The low-level hum is gone! This was with a BACP reader, tho.

Ron Yost

Posted by Gordon McLeod (Member # 33) on 10-02-2005, 02:20 PM:

The cable from the reader to the processor must be splice free and shielded the entire run
The shield terminates at both end
Since blocking the LED removes the hum I would suspect the powersupply has issues

Posted by Steve Guttag (Member # 268) on 10-02-2005, 05:23 PM:

Gord, I was referring to the LED power supply...hence blocking the LED supply removed the stimulus for the hum. A grounding issue will not be affected by the presence of the light source.

As to the shield being terminated at both ends...there is good and bad to it...technically it isn't the best way since the screen is now the reference as well. The key is that both the reader and the preamp must be at the same reference. Additionally, the signal must be shielded. The easy way is to connect the shield at both ends. The better way is to run a separate large gauge wire to bond the reader at the same ground/ref potential as the preamp and then use the shield for just shielding and tie it only at the processor end.

Posted by Sam D. Chavez (Member # 1841) on 10-02-2005, 07:37 PM:

Once again I agree with Steve Guttag. Hmmm.

This is the bst way but geting installers to run a new wire in a retrofit situation is very difficult.

Posted by Ian Bailey (Member # 1752) on 10-03-2005, 07:55 AM:

Steve-I haven't checked it without film (I will do that tomorrow) and no I don't have a digital basement reader.
I will replace the cable anyway to reduce the chance of any problems due to the number of joins.
Are these power supplies repairable?
If not,do I have any choices in models or brands of supplies?
I know that the previous owner had trouble with one of the power supplies and they used a supply out of a computer(switched mode supply)as a temporary measure until the faulty one was repaired or replaced.So I assume these readres just run on 5 volt DC-is that correct?