Help! Whining LetusXL vibration motor. at

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Old September 5th, 2009, 11:57 AM   #1
Join Date: Jun 2009
Location: Newks UK
Posts: 4
Help! Whining LetusXL vibration motor.

Been playing with my LetusXL on my Canon XL2 today and suddenly the motor started making this horrible sound!

YouTube - Whining LetusXL Vibration

I changed the batteries and the same problem. The motor is spinning fine but is making this horrible noise. Usually it is silent.

How can I fix this?

How can I contact Queyen Le?

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Old September 6th, 2009, 12:25 AM   #2
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It is a bit difficult to determine from audio on your short clip.

Three things come to mind.

1. - The groundglass panel may be striking the cylindrical case. To check for this, try turning the Letus through all directions, like roll sideways, tilt front to ceiling and to floor to see if this introduces any change to the noise or makes it go away. If the noise suddenly appeared on first switch-on after a period of storage in the horizontal position over a hot summer, it likely will be this cause.

In this event, all that may be needed is to grasp each of the pillars tweezers and rotate each about 45 degrees to place the high points of each in a new position inside the rubber grommets. You need to grasp the grommets so they do not turn inside the groundglass carrier as you rotate the pillars inside of them.

2. - A groundglass beginning to detach from the panel might also flap and rattle. This sound may reduce the most when facing towards the floor. (It still could be something else making the noise as all sources will be affected by facing the floor as the groundglass movement pattern changes a little when gravity is pulling in a different direction.) Your repair will be to put a few more spots of glue on the edge of the clear groundgass where it it fits into the black groundglass carrier.

3. - The armature of the motor may be touching the inside of ferrite magnets which will be staked inside the can casework of the motor. It is a very tiny motor with equally tiny operating clearances.

The vibration over time may loosen the magnets then polish the contact face of the magnets or can and they may then become free to move enough to pole out on the spinning armature.

Alternatively, the little rear end cover in the motor which carries the rear bearing, the commutator brushes and solder tags is secured by staking flaps on the can end which fold over. I would expect this cause of noise to become incrementally apparent over time, not a sudden onset.

The motor is fastened by the solder tags, the only mechanical support besides a sleeve enclosure which would be prohibitively heavy in this application. I am not aware if in the phone vibrator application it is supported on the tags or by a sleeve molded into the phone case.

Whatever, in the Letus XL, the brothers have applied an adhesive to the can case/groundglass carrier junction which would have taken care of this.

Over time, the adhesive may have detached and the end cover may have loosened in the can case allowing a little movement to occur once the armature spins up and begins to throw the eccentric weight as it normally should.

When the eccentric starts to exert force, the can case will sway on the end cover and then allow the magnets to touch the rear of the armature, thence a whining noise.

If this has happened, the motor may likely also have become difficult to start or start only when the Letus is given a gentle tap.

The only practical cure may be to check if the motor can is moving slightly relative to the groundglass carrier. If it is, then put another few drops of hot glue on the motor to groundglass carrier junction to brace this joint against movement.

Other repairs like opening the motor up to immobilise the magnets in the case or to punch the stake flaps tighter require the motor to be removed from the groundglass carrier. Everything is too small for this to be a practical task for the average punter to take on with any hope of not furthur damaging the motor.

If reglueing the motor does not work, then you might be up for a few vibrator motor. The little dob of glue on the eccentric weight is there for a reason and must be replicated on the replacement motor.

The glue drop is an air resistance to govern the motor speed slightly slower. The resistance also interacts with the torque of the motor and the throw of the eccentric weight to amplify the "kick" of the movement.

I don't know whether the brothers engineered this factor deliberately or arrived at it by happy co-incidence but it is masterly nevertheless.

The brothers also added a tiny dropping resistor to the motor circuit to lower speed and to allow longer duty cycles without shortening the life of the motor. You need to re-install this resistor if you swap the motor out.

This resistor, the solder tags and the feed wiring are all encapsulated in adhesive to immobilise them against vibration damage. You must replace this glue with the same type and use no more than the brothers have done, otherwise the mass of the carrier may become too much for the motor to throw enough distance to eliminate the grain texture.

Your Letus is an XL model which is a few years old. If you have left it switched on and have flattened a set of batteries or two, it will have quite a few hours of running time up and some need for maintenance can be expected.

Please do not take these commments as having any authority or approval from Letus Corp.

Last edited by Bob Hart; September 6th, 2009 at 12:43 AM. Reason: error
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Old September 6th, 2009, 05:50 AM   #3
Join Date: Jun 2009
Location: Newks UK
Posts: 4
Wow thank you for an excellent response. I just switched it on again this morning and the noise has stopped. However I do not doubt that it will return.

I removed the cylinder that houses the ground glass and vibration motor but could not removed the front to access the motor. From inspection I think it seems that there is a fault with the motor rather than anything else.

At this point in time I do not want to fiddle with things too much as a noisy Letus is better than a broken Letus!

Do you know if Letus will still repair the XL model for a fee?


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Old September 6th, 2009, 09:51 AM   #4
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You might be just lucky. If the unit has not been operated for a long time, the motor bearings themselves may have gone a bit dry. They will be plain metal bearings carrying a chrome shaft little thicker than a small dressmakers pin. At that size they may be oilite bushes which carry their own permanent lubrication.

Plain bearinged computer fan motors, over time get wear in the bearings and a slight clearance opens up. They become noisy on start up as the shaft bounces around inside the dry oilite bush and settle down after surface temps pick up a bit and some lube mobilises from within the pores of the oilite bearing material and separates the shaft and bearing surfaces with a layer of lube. It may simply be something like that.

The Letus XL which I modified and which is in the youtube clip linked below has a tendency after storage to rattle the carrier against the casework until it has been run once, then it settles down as yours seems to have done. It rattles because the much heavier weight of the motor I have substituted causes the flexible components to settle in storage towards the cylindrical casework.

If you look at this link, you may work out how to pull the front out of your Letus XL to check the security of the motor and groundglass in its carrier. The thumbscrew which locks the mount in has to be unscrewed completely from the cylindrical case.


If your Letus XL is a later version, there may be two extra screws in the approximate positions my two added screws are located on the underside at the front. The earlier production used the single thumbscrew to secure the front-end of the casework which bears the pillars and groundglass, as well as securing the lens mount.

In my clip, the single thumbscrew was replaced by a longer screw which has a countersunk head instead of the ribbed knob yours will have. This was because I modified the mount itself for improved security and the original screw was too short.

I added the two screws and Letus did likewise either just before or around the same time.

Don't go as far as I did and pull the flip enclosure apart. There is no point and you may do damage like cracking a mirror.

On top of the Letus threads there is a sticky I wrote for the Letus XL which might give you a bit of info.

In the event that the flexible components have slumped a little due to weight in storage, you may find that if you in future store your Letus with the lens mount facing directly down, the problem may not come back.

As for product support and repairs of an older product, you would have to contact Letus at these web addresses which I think I have correct but may be wrongly remembered at or and ask the question.

Last edited by Bob Hart; September 6th, 2009 at 10:16 AM. Reason: added text
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Old September 7th, 2009, 04:41 PM   #5
Join Date: Jun 2009
Location: Newks UK
Posts: 4
Ah so it was you who taught me how to thread my CP16! Nice video tutorials!

It seems our LetusXLs are different. My Letus does not have the circular vibration motor in the middle but has one of these types off to the side.

Some of the other internals look quite a bit different also. My Letus only has a Nikon mount which isn't reversible, well I'm pretty sure it isn't anyway.

So the whining has stopped for now but I fear the motor will need to be replaced sometime in the future.

I have another problem. When focusing the lens the image seems to shift strangely in the viewfinder. Even if I hold the end of the Letus tightly, there is still a strange shift in the image.

Anyway. Thanks for all your help. I will surely return to this thread when my Letus decides to go bad again!
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Old September 7th, 2009, 06:13 PM   #6
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CP16? - Yes it was I.

The focal shift? I am imagining you are referring to a physical movement of the image in the frame when you move the focus ring?

1. If it is shifting when adjusting the relay lens - that is unfortunately a normal state. The early direct relay models like the XL used a modified Minolta stills lens for a relay lens plus an achromat on front.

This lens was not designed to carry a mechanical load so there is either a deviation off the optical axis introduced by relay focus movements if the Letus body is supported or a very stiff focus ring on the lens if it is not supported.

The Letus has evolved a lot since those early days.

2. Another image shift may occur with stills lenses characteristically used on 35mm adaptors. The older metal cased Nikon lenses are better in this regard. Some newer lenses, especially plastic barrelled autofocus lenses with a telescoping or moving piece in the front end move the image quite a lot.

Stills lenses were never intended for motion imaging so it is not a problem for stills shooters but is not a good look on video when pulling focus.

The motor in the centre was my modification. The original Letus motor was on one side as you describe and a similar motor to the illustration you linked to.

Last edited by Bob Hart; September 7th, 2009 at 06:14 PM. Reason: error
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