Film-Tech Forum ARCHIVE: Pops in sound

This is topic Pops in sound - Static discharging in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=009433

Posted by Marin Zorica (Member # 1716) on 08-01-2008, 06:14 PM:

Hi all!

I do have this problem, it happened before two days first time.

The pops is very anyoing and stops in moment I ground the machine, I did use piece of wire and put it between projector and sound rack...and it goes away....i also did check all grounding (there is object from 60's so ground to neutral 0 is used as protection) and every cable ground 2,5mm2 cable goes to main distribution box and they are all connected well. After whole day of checking and so on I didn't find anything wrong....so only option now is to use some wire between machine and rack. Also, on ISKRA housing of photo diodes are like on ernemann IV or so, in that small aluminum housing which is mounted on projector by screw. Here inside of it it's little PCB which hold stereo diode, I did think may bee problem is in this, that metal housing is insulated from projector, in old system with photocell gnd from amp were connected to it, so I was think to get it grounded to machine housing, in moment I did that there were more pops in sound.....that was so strange, I did couple of stereo readers on iskra, none have this problem, and also photo diodes are connected in balanced to machine.

Any ideas.....?? Thanks for help!

Posted by Louis Bornwasser (Member # 3063) on 08-02-2008, 08:23 AM:

As you have discovered, NEVER ground the audio to the projector ground. Always ground the adio pickups to the audio (Dolby) ground.

I spend most of the 70s & 80s removing excessive grounds in drive ins and other old mono systems to make them "quiet." Louis