Film-Tech Forum ARCHIVE: Making Adjustments with a Buzz Track on a Century Head

This is topic Making Adjustments with a Buzz Track on a Century Head 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=009097

Posted by Shane Hoffmann (Member # 1620) on 02-04-2008, 09:35 PM:

Hello all,
My apologies if this has been addressed elsewhere...I haven't had much luck searching the archives for an answer.

I am running stereo surround in a small house off a Century TR-4B Soundhead. I replaced the red LED today and made the necessary adjustments while running DolbyTone. I am satisfied with the volume and clarity, with the exception of a slight, but noticeable hum during quiet scenes. I am assuming it's the result of light spillage, perhaps on the DTS timecode as I've read elsewhere, and the first thing I want to try is a lateral adjustment.

I've never had to run the buzz track on my Centurys before (I've done it several times on Simplex heads), and I don't know what I am supposed to do to. Pardon the dumb question, but what am I supposed to turn, or otherwise adjust, to move the film laterally at the LED?

I appreciate any help!

Posted by Monte L Fullmer (Member # 2797) on 02-04-2008, 11:13 PM:

On the upper lateral guide roller that makes the Davis loop over the scanner drum, there is a locknut on the arm that you loosen (which acts like a pinch lock), and the upper lateral guide roller is on a threaded shaft end, and you turn the kurled end of the shaft to align that upper roller for buzz track alignment. Then, when aligned, you lock down that nut to pinch down the shaft in the arm.

Good luck-Monte

Posted by Shane Hoffmann (Member # 1620) on 02-04-2008, 11:15 PM:

Thank you, Monte. I will get right on that.

Posted by John Wilson (Member # 269) on 02-05-2008, 04:49 AM:

What Monte said. There's nothing easier.

Posted by Richard Fowler (Member # 893) on 02-05-2008, 07:43 AM:

It is easy to do but don't be too rough when loosen and tighten since those aluminum cast damper arms can crack.

Posted by Mark Gulbrandsen (Member # 72) on 02-05-2008, 09:46 AM:

Two things to check before you ever check BUZZ.... check the lateral guide roller for wear of its internal width... and its bearings. If you happen to have the old style lateral guide with oilite bushings then its best to replace those. Be sure the dashpot cup is filled with Silicone Fluid to the correct level and with the correct fluid. If they are not filled with the right stuff to the right level the Davis tight loop will not operate properly. I believe the fluid is FD-21 and the level is very definately marked inside the cup.... at about the two thirds level.

Mark

Posted by John Walsh (Member # 168) on 02-05-2008, 04:44 PM:

I usually didn't loosen/unloosen the locking screw for the roller lateral guide adjustment. As Rich noted, the arm could crack, but also I found that by trying to tighten them, it threw the buzz track alignment off. So I just grabbed that knurled shaft-screw and turned it.

Posted by Louis Bornwasser (Member # 3063) on 02-05-2008, 09:01 PM:

Whatever you do DO NOT loosen or tighten the pivot points for the arms. Many techs will do this since they do not know of the correct adjustment as Monte says. In addition, push/pull the top roller; it is common for there to be "play" in this which is too much. (small ring with allen screw just behind this roller.) Louis