Film-Tech Forum ARCHIVE: Analog Sound Issue

This is topic Analog Sound Issue in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Tom Wienholt (Member # 1510) on 12-15-2009, 09:39 PM:

Equipment:
CP-55 w/Dolby SRA5
QSC USA 900 amps
BACP Reverse Scan Soundtrack Reader

Problem:
There is a constant ticking/popping/tapping sound coming from the stage speakers throughout the entire movie. It is a constant sound like a drum beat. This happens with all movies in this auditorium so damaged film is not the issue. The distortion is not present during intermission/non-sync music.

Any help or suggestions would be appreciated!

Posted by John Wilson (Member # 269) on 12-15-2009, 09:41 PM:

Have you tried turning the processor off and on again?

Is the ticking in all channels?

Posted by Ian Parfrey (Member # 5122) on 12-15-2009, 11:27 PM:

What's the frequency of the ticking i.e how many ticks per second?

Does it coincide with any indicator lights on the processor?

Posted by Monte L Fullmer (Member # 2797) on 12-16-2009, 12:45 AM:

Sounds like you got a scanner drum that it has on its corner, a chunk of goo or splice punch hung up on the edge of the drum that is being picked up by optics

..or, you got a nice flat spot on your lateral pad roller on your Simplex (if this is your equipment since you didn't state what you have to run film through in your booth..) soundhead that will cause the thumping..

...scanner drum bearings are going "bye-bye"

...or even worse, a flat spot on the scanner drum itself.

Some areas to look into

-Good luck - Monte

Posted by Gordon McLeod (Member # 33) on 12-16-2009, 10:07 AM:

If you have no film playing and select SR or A type is it still there if so it is probably a regulator issue

Posted by Manny Knowles (Member # 1171) on 12-16-2009, 12:59 PM:

I had this problem once and it turned out to be a "chunk of goo" on the edge of the drum, as Monte suggests. I'd recommend trying that first since it's super easy to check/fix.

I know this will make me sound like a mushy prick, but "Happy Holidays" everyone!

Posted by Richard Hamilton (Member # 321) on 12-16-2009, 01:42 PM:

Tom, what soundhead is it?

Rick

Posted by Tom Wienholt (Member # 1510) on 12-16-2009, 08:16 PM:

Gordon,
Yes the problem is still there with no film playing. So, this obviously has nothing to do with the sound head. What else can I check?

Posted by Ron Curran (Member # 3631) on 12-16-2009, 11:10 PM:

Try re-seating the cards in the processor. We had such a problem once and pulling the SR cards out and putting them back in cleared it.

We now clean the plates or pins on cards as a regular procedure (or when we remember).

Posted by John Wilson (Member # 269) on 12-17-2009, 12:35 AM:

quote: Tom Wienholt
So, this obviously has nothing to do with the sound head. What else can I check?

quote: John Wilson
Have you tried turning the processor off and on again?

Is the ticking in all channels?

Tom,

How about ruling out what's being suggested to you or answering our questions? It may well keep us interested in your plight and end up solving your problem.

Posted by Michael Voiland (Member # 5386) on 12-17-2009, 03:03 AM:

With everything on but not running except the scan reader
do you hear at hum that sounds like this

quote:

The link below is just a little video that I whipped up that has a 60htz tone electricity uses 60htz and ground loops can cause a problem.
http://www.youtube.com/watch?v=SVZ2P0KsLic

if so you have a ground loop in your audio system check for loose ground wires.
If it only happens when a motor is running you could be picking up interference on an unshielded conductor.

Edited to include description of link and quote tags.

Posted by Louis Bornwasser (Member # 3063) on 12-17-2009, 04:29 AM:

What kind of LED reader is onboard tht soundhead? Louis

Posted by Gordon McLeod (Member # 33) on 12-17-2009, 10:52 AM:

Since it has been determined that the problem is in the optical chain even with no film running I would next disconnect the input to the optical preamp and see if it is still there that will narrow it down to the processor of the LED/Reader
The best method of trouble shooting is to break the problem in half so that it will automatically eliminate 1/2 of the possibilities in one pass

Posted by Jim Cassedy (Member # 4115) on 12-17-2009, 11:00 AM:

I was getting a ticking/buzzing from a BACP reader
that was missing the little screw that holds the
"electronics" in place. (The part with the little
handle, under the row of small LED status lights)
The card eventually loosened up enough to where
some of the contacts inside were just barely
seated, so there was intermittent noise caused
by any slight vibration- - even just walking
across the booth. Re-seating the card and
replacing the small screw solved everything.

I don't know if this is ths ame problem you're
having, but it's worth a look!

Posted by Frank Angel (Member # 248) on 12-17-2009, 02:24 PM:

He said it is a rythmic ticking so it is not ground loop.

quote: Tom Wienholt
Yes the problem is still there with no film playing. So, this obviously has nothing to do with the sound head. What else can I check?

Is it there with the projector motor off? With other motors in the booth off?

As Ian suggested, check for electrical equipment that has blinking lights, try to find something that matches the ticks.

Do you hear the ticks with the CP55 in MUTE mode?

Is it there with the motor off?
Is it there

Posted by Sam D. Chavez (Member # 1841) on 12-17-2009, 10:38 PM:

Jim,

What little missing screw? There is a hole in the board to access the lateral adjustment hex socket for projectors that do not have a moveable lateral guide roller, for instance, Christie, Cinemeccanica, etc.

Very creative way to hold the board in although not usually necessary. Kudos!

Posted by Tom Wienholt (Member # 1510) on 12-18-2009, 01:20 AM:

Ok, I have some answers. I tried re-seating the cards in the processor and the ticking is still there. The ticking is only coming from the three stage speakers, not surrounds. Tried disconnecting the wires coming into the CP55 from the LED reader - still ticking. Ticking is there with the motor on or off, film or no film, LED on or off, and with all power shut off in booth except to processor and amps. No ticking when processor in "mute", non-sync, and bypass. Ticking when processor is in A or SR modes. I assume that this means there is something going on within the processor. Any more suggestions?

Posted by Gordon McLeod (Member # 33) on 12-18-2009, 02:40 AM:

cat 150 is very suspect

Posted by Louis Bornwasser (Member # 3063) on 12-18-2009, 08:33 AM:

You can always bet on the 150 due to its complexity. Also, logically it is on/off in step with your symptoms.

I would remove the preamp and check for ticking; then remove the nr cards and check. Leave each card out as you go. I think when your remove the 150 the ticking will stop. Louis

Posted by Tom Wienholt (Member # 1510) on 12-18-2009, 02:42 PM:

Well I finally figured it out. I swapped cards from a known working processor and discovered that the problem is a bad Cat 222 A-type NR card. This is the second failure that I have had with these cards this year. In a different CP55 processor I have, the left channel had major distortion in it caused by a bad Cat222. Are these cards known for being unreliable?

Thank you all for your help. It is greatly appreciated.

Posted by Louis Bornwasser (Member # 3063) on 12-18-2009, 10:08 PM:

I don't think I have ever replaced one. I have 40-50 in stock. Usually I use the 222sr/a card. Louis

Posted by Steve Guttag (Member # 268) on 12-18-2009, 10:22 PM:

Oddly enough, I've had MANY Cat 222 cards fail...not as many Cat 222As and just a couple Cat 222SR/As.

Steve

Posted by Tom Wienholt (Member # 1510) on 12-18-2009, 11:02 PM:

What is a Cat 222? I thought that there were only two types of this card (Cat 222 A-type and Cat 222 SR/A)?

Posted by Louis Bornwasser (Member # 3063) on 12-19-2009, 06:11 AM:

The 222sr/a card has two parts. The original a board and an add-on sr board. Half of this is referred to as a cat 222a board.

The original version of this is the cat 222 board which plays back "A". Louis