Film-Tech Forum ARCHIVE: Brenkert BX60 Travel Ghost

This is topic Brenkert BX60 Travel Ghost in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Gordon McLeod (Member # 33) on 11-24-2006, 12:16 PM:

I have been having issues with travel ghost on BX60 with the single rear shutter
It is a small amount going both directions (but still unacceptable) It appears that modern Xenon system allow a small amount of light to pass around the shutter. I also noticed that the center line of the shutter is above the apperture and I assume that with the long working distance and slow f speed of the enarcs that the corner of the shutter wasn't an issue
I have widened the shutter blades with riveted on tin (but this does through the balance off) but was wondering if anyone else has experienced this and solved it
It appears that there were only three shutters made for the machine
A narrow one for the twin front back shutter version (BX62) the standard for single shutter which we have and a 3 blade which I have never seen
So before I consign our remaing 20 BX60 to the recycle and replace them with XLs I thought I wouold toss this around

Posted by Louis Bornwasser (Member # 3063) on 11-24-2006, 04:36 PM:

Is it possible that reflections around the shutter blade are some of the problem?

How about shutter oscillation (like Centurys)?

How about a fixed aperture in the area behind the gate (like an XL)? I think they call them heat shields. (In SA Centurys it is possible to reduce apparent shutter oscillation by making the shutter hole the same as it is on Century C.)

Based on what I remember from 20 years ago, I'm betting on shutter oscillation. Louis

Posted by Luciano Brigite (Member # 1104) on 11-24-2006, 06:11 PM:

I used to take care of a few BX60 in two theatres and didn't have this problem with any of them,even after changing the reflectors from 860mm to 750mm (distance from reflector to film) ,in some projectors it usualy happens when the reflector is replaced by another with a shorter distance.
When such problem happened,and it was sure the cause was the shutter, I took the original one out,put on a sheet of metal,traced the countour,maked the holes,etc then enlarged each blade in 10mm,in one direction only. cut it out,made the holes and put in place . in most of times it solved the problem.
I think it's a good idea,before go ahead and cut a new shutter blade ,to make sure htat there's no play with on hte shutter shaft,gear and so on ( tho as you said htat the travel gost happens boht ways I htink it's more hte shutter itself than anything else, but doesn't cost taking a look on hte shaft and gear..)

Hmmmm....
sending them to recycler??? [Eek!]

if it's going to happen for sure drop me a message... I'm looking for some parts... specially intermittents..

Posted by Mark Gulbrandsen (Member # 72) on 11-24-2006, 06:14 PM:

I've experienced this mainly with older Xetron lamphouses whose cone of light is still quite large in diameter hitting the shutter. I've also experienced this same problem on Century's with Xetrons many, many times with the standard diameter shutter blade. Moving the lamphouse back a bit sometimes helps as you can cut the cone of light at a slightly smaller diameter but this may also louse up the lamp focus somewhat... its a trade off... or use larger diameter blades and sometimes you have to doink around with the Century shutter housing which will always be just too small for the larger blade. Note that I have not experienced this with the Big Sly conversion kit in a Xetron.

Hope some of this helps...
Mark

Posted by Robert Throop (Member # 61) on 11-25-2006, 11:25 AM:

Gord,
Could this possibly be a BX62 that originally had front and rear shutters? The shutters were narrower.
Bob

Posted by Gordon McLeod (Member # 33) on 11-25-2006, 12:22 PM:

The shutter blades in question match the spec of the BX60 shutter I have some of the bx62 ones as a comparison
Because of the fact we have to run subtitled caption prints even a small amount of ghost is unaccpetable
The amount I had to increase the blade by was about 18mm
It appears that the angle was also critical
Some of these are installed with ORC consoles the cone of light is very narrow so I didn't think this would be an issue
There is no appreciable play in the gear train

Posted by Jonathan Bodge (Member # 4072) on 11-26-2006, 07:44 PM:

New to forum....I observed this with the Kneisely Dog, I mean Pup, overshoot was my theory. I always marveled at the BX 60's blade odd shape with the leading edge being different than the trailing edge...oh those engineer types....