Hi,

Some of my turnout motors give a buzzing noise when activated in one direction. The turnout points are shifted correctly but the buzzing continues for a short period after. There is no buzzing in the opposite direction from the same motor.

It this a known issue and is there a solution

Thanks in advance.

Thanks David,

Nothing found underneath the C-bed.
The turnout points are shifted correctly. Hand shifting is going ever so smoothly - no mechanical obstruction.

As far as I know there are no adjustments available for the motor assy. so may be it is just something to accept as is. It does work correctly, but it is an irritating noise. [:(!]

How are you activating the point? manual, k83w/Keyboard, k83w/Memory, k83w/PC .............

I operate my turnout motors conventionally, with a control box, and some of them buzz as well.

It seems to be random. Some motors do it all the time in one or the other direction. Some motors never buzz. They always do the job and switch the turnout, though.

I just live with it!

Ray

Yes there is. The motors have end shutoff contacts, meaning, when the motor reaches the end, the power to the coil is not needed and then should be cut automaticly. I guess this is what fails; for example, the motor reaches end an shuts off, but bounces, gets power again, reached power, and so forth. Bouncing is a known problem with first series motors.

The decoders deliver DC, so if you hear buzzing, it's not AC. The only thing I can thing of is such a bouncing.

Fix? Try insert a resistor, so the motor gets less power, much enough to do it's work. I have a suggestion of value.

/Lars

Hi Lars. Thanks for your reply.

This explanation sounds very reasonable to me. I think I will experiment with that fix. All my motors are less than 2-3 years old, so they could hardly be of the first series.

What is your suggestion of value (or did you leave out a no

Benny,

Because of the point motor design (I wont strictly say bad but it could be better) It needs to work well with a range of mechanical resistances as well as poissible voltage drop over the layout. Early productions had one switch only.

If anything, it is the buzzing ones that are working well with good powerfeed and light turnout resistance. Marklin ship a resistor with each k83 to help overcome this "if the k83 is wired close to the CU" by reducing the grunt in the puls. But make sure you still get a reliable throw of the switch.
I will take buzzing anyday over a potential derailment unfortunately, however it is still possible (if not an undesirable side effect) that when power stops the actuator is in the bounceback position and the tounge of the point floating.
One other suggestion, as you are using the CS, is to alter the pulse time for the magnet. However this will affect both directions and the load may not be symetrical.

If (as I would recommend) you are thinking of using seperate booster to drive your accessories (k83/k84) in order to prevent the pulse causing your locomotive lights to dim. Then totally bypassing the switch is an option. As long as your pulses are indeed just pulses (as compared to a permant on state caused by a shoe siting on a contact/circuit track) then you will get a single firm switch.

And just something nagging me about your description - As Lars said the k83 provides a DC pulse so we are working on the basis that the buzz is mechanical and the result of uSw cutoff AND bounceback. This buzzing should be short lived as the actuator will eventually come to rest in the correct place.
If the buzzing does not quieten (change pitch) even within the fraction of a second I would have to wonder if an AC component was getting in .......
Make sure the metal case of your point motor is not touching the rail under the track . By itself this is not a problem but if the circuit board within the casing is also contacting the metal case it may make an unwanted circuit.

Hi Peter, Henk.
Thanks for your replies.

So far I never had de-railing due to the switch points floating midway between end positions.

I cannot as suggested decrease pulse duration, it is already at the lowest possible value - 250 ms.

Once I get a permanent larger layout I will have to separate the accessories from the track power using boosters.

As for the switching itself, it is done very quickly and the buzzing is heard briefly after completion in what seems to be more like half a second, but is probably no more than the 250 ms supplied by the CS.

I have pinpointed the worst motor and opened it to see the cut-off u.sw.'s. It is located in a 3-way turnout and buzzes everytime
in one direction.

It is easy to see the u.sw.'s - 1 in each end on this pic.:



To my surprise it does not buzz at all when it is taken out and the covers have been removed. It looks like some mechanical binding when assembled.

I will return later with the result when it is re-assembled and re-installed.

As said earlier, when the motor was stripped off of the two metal covers there was no buzzing. Then with the covers re-installed but the motor still in my hand - no buzzing. When put back in the 3-way turnout - buzzing 9 out of 10 times in the one direction only, as before.

When the motor was moved to one 24711 slim turnout - no buzzing!

Then a new motor was installed in the 3-way - no buzzing!

Conclusion: perhaps some tolerences on both turnout and motor, skewed from zero values, working against each other. I swapped a number of motors around last night - took hours - but I am almost buzzing-less now [:0] and satisfied .
Could only do it because I still have a floor layout, I guess.

I find it quite natural that you get the buzzing when there is a particular relationsship between mechanical properties, and eletrical. If you remove for example some mechanical load, you change the system.

My first theory was that it was just a "bounce", but it might also be problem with the spring between motor and switch tongue. You could check if it's possible to move the arm further when the switching has been done. But I'm not sure if you can access it when installed.

Renes idea is also good. I recall that I have sometimes been able to make turnouts work better by loosen one of the screws, make sure that the turnout lies flat without mechanical stress, and such.

/Lars

I have always fixed the motor with the two screws supplied as it is supposed to, but one might benefit from loosening one or both screws a tiny bit.