Altman 1KAF Fresnel

[Micki]

Hello,
This is my first post, but I've been learning from Control Booth for a while now

I am helping with some lighting maintenance at a college I often design lights for, and we are stumped by a problem with almost all (28?) of the Altman 1KAF Fresnels. The slide on the back to move from spot to flood will spring back to "flood" and won't stay on spot; this happens always when the light is pointing straight down, and about half of them will do it even with the light horizontal.

I am not even sure where to start with this issue. Any suggestions?

Thanks in advance!
~Micki

 

[ship]

Hello,
This is my first post, but I've been learning from Control Booth for a while now

I am helping with some lighting maintenance at a college I often design lights for, and we are stumped by a problem with almost all (28?) of the Altman 1KAF Fresnels. The slide on the back to move from spot to flood will spring back to "flood" and won't stay on spot; this happens always when the light is pointing straight down, and about half of them will do it even with the light horizontal.

I am not even sure where to start with this issue. Any suggestions?

Thanks in advance!
~Micki

I have one, I bought it used with a name on it of "Old Rover". Believe it was the first light I ever bought. Wonder now if the name is less in reference to it being rental sock to the wandering focus issue also. Sort of takes on a new light for a name on the light - a little less about liking the fixture than titling it as a problem one. I also note that when it was last used it had a cable tie between the focus lever and the handle to retain position in seemingly a similar problem. http://www.altmanstagelighting.com/altman-lighting-fresnels/1KAF/1kaf_spm[1].pdf Altman exploded pictorial is incomplete about this section of the assembly it would seem on looking at it. Seemingly missing parts in the drawing.

It's a question I knew about many years ago and long since forgot about. Give me a few days and I will pull mine down from the museum and tinker with it a bit to see what is causing the problem and recommend a solution.

Side note... I do remember that it's specified beam spread was a little less than a 65Q Fresnel.

 

[Les]

I've seen this issue as well. Seems that bailing wire was the common fix much like Ship's observation. In reality, tightening something on the slide might fix it.

On a similar note, make sure the insulating pads between the lens and lens mount are intact. Altman had an issue with those a long time ago which caused lenses to crack. I believe there was a recall or offer for free parts.

Old Rover - I like that.


Sent from my iPhone using Tapatalk

 

[DavidNorth]

Well, every 1KAF I've ever used has done this. IIRC, there is a nylock nut on the bottom of the unit that can be tightened slightly which will increase the drag on the sled and keep it in place. If tightened too much, the sled won't move easily or at all. It will loosen again in the future and the sled will slip again which means you should tighten again. I got to where I carried a nutdriver with me to focus calls. Wish I could remember the size. Seems like it was 5/16" or 3/8".

It is possible that someone knows a better fix than I do. This is just what I did. You will find lots of these units out there with tie line on the focus handle and connected to the flood/zoom knob.

David

 

[Micki]

David,
That does it! The nut is 3/8". This seems like something Altman should have put into the manual... And even if it's not the intended purpose of the nut, it's a much better solution than bailing wire or tie line
Thank you all for your QUICK responses! (I tried to reply Friday afternoon, but I couldn't get a good internet connection.)

~Micki

 

[ship]

Well, every 1KAF I've ever used has done this. IIRC, there is a nylock nut on the bottom of the unit that can be tightened slightly which will increase the drag on the sled and keep it in place. If tightened too much, the sled won't move easily or at all. It will loosen again in the future and the sled will slip again which means you should tighten again. I got to where I carried a nutdriver with me to focus calls. Wish I could remember the size. Seems like it was 5/16" or 3/8".

It is possible that someone knows a better fix than I do. This is just what I did. You will find lots of these units out there with tie line on the focus handle and connected to the flood/zoom knob.

David

Sorry been a busy week and have not had time to pull it down from the pipe or finish up other lights in the works. With any luck I will have time tomorrow to investigate.

 

[StradivariusBone]

Just hung 15 of these and was banging my head on the pipe trying to get them to stay focused. This is why I love Controlbooth, you all can read minds.

 

[ship]

Just hung 15 of these and was banging my head on the pipe trying to get them to stay focused. This is why I love Controlbooth, you all can read minds.

Still busy... salary/staff and almost planning a day off for Friday (I can do this - at least when not too busy) to play with this and other stuff in the works, but too much to do... than tonight an asking of 40x lamp bar types to be fabricated next week which take 8 thru 16 hours each dependant on labor supplied, a few cable builds and two special projects for gear... It's touring season! Still might take Friday off in working too many hours lately, just go in for a few hours and get stuff done... than go home and get finished many projects plus have a look at this Fresnel. Normally, that takes half the day at best or a full day to get stuff bought, people managed etc.

 

[ship]

Finally had time on Friday to get the fixture off the pipe. Tonight Sunday after 10, finally had time to look at it. Sorry, busy weekend/weeks - baby time, and other stuff and finished inventing two new things for work.

I note on my version, it has a cam style yoke but isn't using it, instead it has a clutch washer reversed and useless as a hold down in not doing either system of lock down of the yoke. Seems really odd in all the holes and the cam in place but not using this clutch plate there. Has the parts for clutch break but is dogmatically using clutch cam parts - this in reverse. Very odd yoke assembly I find on mine and will have to correct. Are your's the same? Not a problem persay other than that you really cannot dog down the fixture as would seem a normal thing to be able to do.

On the rear focus lever, I am noting it's wanting to slide towards flood by way of perhaps warped parts by way of gravity or expansion and contraction. O Warp in the cast lever arm wants to send especially the spot towards the flood but also centers the flood some towards the center of the warp. Say the center of this warp is 2/3 towards flood position.

Solution will probably be in bulking up the glide plates (perhaps replacing what part is there) in perhaps there is a part warn thru in thickness/tension or adding something under the pivot arm to help a parallel even travel. Next week I will be on vacation, suspect by than if not during the week I will have time to tear this apart and analyze. Until than, what does the lamp base plentium plate glide on? Are they just glide plates or also friction plates? Is there an adjustment or able to replace what is there in being warn? Only after that would I start looking into modification.

Closing up the fixture again for now.

 

[ship]

Opened up the 1k Fresnel and think I found what parts I would replace or adjust:

Part #31-HR10 is the side lock nut you have been tightening. While I like the easy access to the nut, too much tightening of it would cause wear to it’s ping allowing it to loosen as you focus.

I also noticed a slight amount of wear on part #14-0041 and spun them 90 degrees. They help the base plate (plentium) glide inside the frame. It’s possible they also help to tension the plentium #12-0041-25 plate some also and if showing a lot of wear or flat spots they should be replaced.

You might also want to look for some wear to part #25-0180 requiring replacement or exchanging one for another.

Finally, I was correct that finding a reversed 12-0012-10 on the clutch break side and no break knob, as with a non-Altman male knob similar to what will have been on a 360 radial fixture are the wrong parts & will be corrected. Thanks for the chance to re-visit this fixture I have not touched in many years.