8mm Forum: Beaulieu 708 EL speed adjustment

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Posted by John Hermes (Member # 1367) on March 27, 2014, 06:19 PM:

I have the twin-track model of this projector and a problem. When switching the control knob from silent to sound, the projector speeds up slightly. The fine-tune speed control knob on the front doesn't have quite the range to get the speed back where it should be. I see there are a number of pots on the board inside the projector. Do these pots (or some of them) control the basic speed of the projector, ala the Elmo ST-180?

Posted by Andrew Woodcock (Member # 3260) on March 30, 2014, 09:19 AM:

John, when you get hold of the tensioner adjusting roller assembly, does the machine decrease in speed when you pull it towards you and then increase again, as it should, when you release the mechanism?

Posted by Rob Young. (Member # 131) on March 30, 2014, 05:21 PM:

Crickey. All seems wrong.

Switching to sound may slow down projection speed a tad, but the speed adjust should easily have enough range to correct.

Following this up in a new thread;

"Beaulieu Owner's Club".

Posted by Andrew Woodcock (Member # 3260) on March 31, 2014, 11:18 PM:

The questions i asked earlier Rob were just to test the speed adjusting mechanism electrically and mechanically without film loaded. This just gives you a rough idea of what is wrong if anything at all. If all is well, when the mechanism is pulled gently towards the take up reel, the machine should slow down quite an amount, when released it should go to full speed which is greater than 24fps. when switching from thread to project the tension idler finds its position electro mechanically to keep the machine dead on 24 or 18fps when in fixed mode with film loaded.

[ April 03, 2014, 04:38 AM: Message edited by: Andrew Woodcock ]

Posted by John Hermes (Member # 1367) on March 31, 2014, 11:33 PM:

Andrew, I haven't had too much time to fool around with my Beaulieu, but it seems the tension arm is operating as you described. I played an Elvis digest today at 24 fps and it sounded correct. My issue the other day was at 18 fps. Is it normal for there to be a speed change (faster) when switching from silent to sound position?

Posted by Andrew Woodcock (Member # 3260) on April 01, 2014, 02:17 AM:

Hello again John, yes that is perfectly normal when the sound heads load but speed should stabilize very quickly, much quicker than say a standard Elmo ST1200.

Posted by Andrew Woodcock (Member # 3260) on April 01, 2014, 02:18 AM:

Hello again John, yes that is perfectly normal when the sound heads load but speed should stabilize very quickly, much quicker than say a standard Elmo ST1200.

Posted by John Hermes (Member # 1367) on April 26, 2016, 01:09 AM:

Well, back to this topic after two years. I recently purchased a Beaulieu 708 EL service manual. It shows the "speed pots" on the board in back. There are four pots lined up next to each other and, from left to right, they control 18fps silent, 24fps silent, 18fps sound, and 24fps sound speeds. I also picked up a little gizmo from Van Eck Video Services which you can aim into the lens of a running projector and it will tell you the frame rate. So I loaded up some film and adjusted all the pots for the correct speed. Everything seems to be working okay now!

Posted by Rob Young. (Member # 131) on April 26, 2016, 03:18 AM:

That's great news, John.

These are terrific machines when working correctly.

Enjoy!

Posted by Andrew Woodcock (Member # 3260) on April 26, 2016, 03:57 PM:

The best of the best Rob, when all is as should be!
Quite correct there Rob!

Well done here John btw, glad you've arrived at a happy place here with your particular machine here at last! [Smile]

Posted by Phil Murat (Member # 5148) on May 04, 2016, 02:43 AM:

High Rob,

Here some records* upon Speed speeds adjustment on a Beaulieu (Film loaded) :

SILENT :
MINI ==> 23,88 Fps
MAX ==> 24,12 Fps

SOUND :
MINI ==> 24,06 Fps
MAX ==> 24,12 Fps

* Recorded with an Electronic Frequencemeter(Low Frequency) and probe installed on the 3 blades Shutter.

As the speed moves from Min to Max as a périod (1 to 2sec) , the actual speed is at the average of both values.

When speed is properly setted there is almost no differences between Sound and Silent mode (Except instantly when changing knob from Silent to Sound).

The "variable" mode offers a range from 6 to 8 Fps (21 to 27 Fps for 708 EL MONO)

Posted by Andrew Woodcock (Member # 3260) on May 04, 2016, 02:56 AM:

Have you gained the above initial values in "fixed" mode Phil?

In other words, is this the level of variation you are witnessing at different times in fixed speed mode?? [Confused]

.06 fps is still very good stability and variation btw if this is what you're pointing out here Phil?

Posted by Phil Murat (Member # 5148) on May 04, 2016, 06:09 AM:

High Andrew,

That was sample of records for "Fix" values (24 Fps).

When setted on "Variable" Mode, target 25 Fps :

MINI ==> 24,99 Fps
MAXI ==> 25,04 Fps

Posted by Andrew Woodcock (Member # 3260) on May 04, 2016, 06:12 AM:

Thanks Phil,

Superb stability demonstrated there then! [Smile]

5 hundredths of one frame per second in between any two random test frame rate samples in run, cannot be contested...outstanding result!

[ May 04, 2016, 07:59 AM: Message edited by: Andrew Woodcock ]

Posted by Rob Young. (Member # 131) on May 04, 2016, 03:11 PM:

Thanks for the useful info, Phil.

Oddly, I have had some sound prints which seem to present a degree of drag on the 708, with the result that the sound seems a little slow.

Switching to variable speed adjustment and giving it a nudge to increase speed always seems to fix this.

When I originally posted John, my concern was that he didn't have enough adjustment in variable mode to correct any audible abnormalities; however now that he has fixed the problem by adjusting the speed pots, hopefully he can now enjoy the fabulous Beaulieu.
[Smile]

Great to know just how accurate a smooth running 708EL is though Phil!

Posted by Andrew Woodcock (Member # 3260) on May 04, 2016, 05:28 PM:

Something's wrong then Rob. In "fixed" speed mode, they really should be sounding spot on with your or John's machine here Rob.

It's a strange one is that???

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