Film-Tech Forum ARCHIVE: Noisy Irem

This is topic Noisy Irem 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=005080

Posted by Antonio Marcheselli (Member # 373) on 07-09-2003, 05:19 PM:

Hi everyone

I would like to fix two of our old IREM rectifier that are very noisy. I read on the manual the procedure to fix it (loose the main screw and check the tow others near the central one until the noise stops) but I have a question. I follow the instructions but I found that my metal screwdriver is strongly attracted by the coil while the rectifier is running. Is it safe to use a metal screwdriver? Should avoid something?
Do you have some "safe" suggestions before I attempt to fix them?

Thanks!

Antonio

Posted by Jason Burroughs (Member # 68) on 07-09-2003, 05:31 PM:

You will need to use a non ferrus screw driver to perform this task. You'll need something like an aluminum screwdriver or other metal that is not effected by magnetic fields. Other than that its safe.

Posted by Gordon McLeod (Member # 33) on 07-09-2003, 05:34 PM:

If you are unsure of the procedure or are inexperienced with it call in someone who is

Posted by Chris Markiewicz (Member # 1415) on 07-09-2003, 06:32 PM:

You can get brass rod stock from a hardware store, grind or file one end to make a screwdriver blade, and bend a right angle on the other end for a handle. Be sure and wear insulated gloves when doing any adjustments. Sometimes those screws can be difficult to turn. It should not take much to quiet the rectifier down. The noise is from lose laminations in the transformers. Make sure the lock screws are not too tight, since that will make it difficult to do current adjustments.

Posted by Antonio Marcheselli (Member # 373) on 07-09-2003, 08:51 PM:

Thanks for all suggestions!

Antonio

Posted by Tim Reed (Member # 137) on 07-09-2003, 10:57 PM:

quote:
The noise is from lose laminations in the transformers.

I'd always found IREM noise to be from the adjustable core. The adjustment screws help to center the core in the windings.

At least, that's been my experience. [Smile]

Posted by Mike Rendall (Member # 1499) on 07-10-2003, 03:06 AM:

I agree with Tim's post. Our IREM is noisy from time to time, the noise is due to vibrations from the coil adjustment screws (either side of the recs).

But as you have to adjust when the juice is on, if you are at all unsure then let a qualified person do it.

Mike

Posted by Phil Hill (Member # 371) on 07-10-2003, 04:11 AM:

Ditto all of the above!

They are great power-supplies, but a PITA to make quiet...AND hold the adjustments!

>>> Phil

Posted by Rob van Ede (Member # 1457) on 07-10-2003, 07:34 AM:

One of our IREMs was very noisy too, and a solution for this was to tape the current adjustment wheel to one of the handles on the side of the power supply. It's very quiet now and the wheel cannot be turned by accident.

Rob

Posted by Don Sneed (Member # 955) on 07-11-2003, 06:56 PM:

All the above is correct....here is what I do...the rectifer coils has adjustment to put pressure on the core to stop the noise...there are three screws, the one in the middle has to be loosen to adjust the other two, turn each one until the noise quits or down in volume, then tighten the center screw back to keep the other two from coming loose...if the first coil you don't change a thing, go to the next, do the same thing, if still don't work, go to the next ect.ect....if still don't clam down, go to the other side of the rect. & do it again until you find it....I use a reg. screwdriver, yes you can feel the magnetism, but don't be alarm, just don't let the screwdriver go inside the coil [Eek!]

This should be a big help to you...Good luck !!

Posted by Antonio Marcheselli (Member # 373) on 07-12-2003, 06:57 AM:

Don,

Yes, it is!

Thanks for your help!
Antonio

Posted by Josh Jones (Member # 447) on 07-13-2003, 05:52 PM:

One of the theaters around here has the same problem, only with noise bleedthrough to the floor below. They had to build sandboxes to decrease the noise transmission.

Josh

Posted by Phil Hill (Member # 371) on 07-13-2003, 06:20 PM:

I always set them on rubber damper pads...

Sandboxes will work...just don't have a booth cat.... [Big Grin]

>>> Phil

Posted by Gordon McLeod (Member # 33) on 07-14-2003, 08:12 AM:

Hockey pucks make great isolators to stop noise transmission through the floor