I have approximately 16 switch decoders that were installed in 1996 versions of C track switches 24611 and 24612. I don't have the part numbers for them but I assume they are the first versions of the 74460 type. The circuit boards are imprinted 600099 Ver. 1.0 Weichendecoder.

While they activate with the correct address settings I notice that they seem to pulse the switch motors. I get a chattering sound when they trigger the switch motor in either direction rather than the solid clicking of a switch motor you get either through a K83 or a 74461. I have tested the switch motors directly and they provide the solid clicking sound when powered from a K83

Has anyone else noticed this? Am I asking for trouble by installing these in a permanent layout or do they indeed pulse the input to the switch motor and cause no real harm?

I really don't want to buy 4 more K83s or 16 x 74461 units.

Peter

Hi Jean,

Thank you for your response, however, it is not the solenoids or switch motors nor a voltage drop problem. As per my original message if I test the switch machine 74491 (less than a year old) directly it "clicks" just fine in either direction. If I connect it to a new series decoder 74461 it again "clicks" just fine in either direction. If I connect it to one of the old 1990s decoders it stutters to its correct position. I have tried 3 of the old style decoders and the reaction is the same for all regardless of what style switch motor I use.

I have test ports set up right next to my CS2 so the power feed to the test panel is less than 30 cm away from the power source using 16 AWG gauge wire. More than adequate.

It is obviously something unique to the old decoders. I'll try and take a video and see if the sound difference can be heard clearly.

Cheers
Peter

Hi,
It's been a very long time since I've used those decoders but I don't remember noticing such problem.
Initially my first thought was as well you had high resistance on a long cable but now that you say it happens next to the CS leaves me wondering. If it happens to all of them yes, change the duration of the pulse and see what happens. I know you don't want to spend but unless you solve the issue I would think twice about placing them in a permanent set up as you know how hard it can be to change something once is embedded in scenery. Although I find it unlikely that all of them are faulty.

You are correct and I have just encountered the same thing. I experimented on 2 switches. First I shorted out the micro switches in the switch motors to ensure that was not the problem. Then I tested the old style decoder with the switch machine before installing into the actual C track switch. Got the same pulsing noise in both directions, but it worked. I then installed the assembly in to the C track switch and it worked in both directions with the pulsing sound but very weak in the straight setting. After 4 or 5 tries it consistently switched to the turnout position but not the straight position. I removed the decoder and connected the optional yellow-blue-blue connector cable to the same switch and a K83 output. Works consistently each time in either direction.

So obviously there is something different about these 20 year old decoders as to how they provide an output to the switch machine.

Therefore, you are correct that I would be asking for problems on a permanent layout.

Peter

I just bought a CS 2 in December and all of my turnouts have old '90's decoders with dip switches and they are working perfectly. The only thing I had to do was to increase the duration of the pulse to something like 350-400 ms to get clean, reliable operation.

Hi!
I take it as "Working perfectly since the settings have been changed."
No conflict, but the information that it didn't work perfectly with the default settings.

Default setting is 200 ms, so doubling that to 400 ms makes me wonder how long the switch motor will last?

'wonder how long the switch motor will last?'

Exactly.

I've seen this discussion about undertrack decoders on the Marklin B&G, lots of times before. I use them myself on my table top, C Track test track, to save untidy wiring

However, I would not consider using them on a permanent layout where I would be screwing the track down and embedding it with ballast.

They will have a small second hand value, and then spend approx. 20 euro on say Viessmann K83s to operate four turnouts. This seems like piece of mind rather than years of frustration. All old electronic stuff these days is suspect, doesn't matter what it is. I bought three of mine ex starter sets and two used off Trade me, all OK so far but they are all approx. 2010 ish vintage

I have a few 5211 Viessmann which I use on my modules, which is the spec for the modules, because of the external power supply option and external programming ability, and I used to use them on the table top, test layout, but got sick of the wiring when I wanted to change the little layout around, but again they're not for a permanent layout, and IMHO, any body using the undertrack decoders for a permanent layout, is on a hiding to nowhere !

There is a saviour for their use, by cutting a hole in the base board, to the almost size of the turnout, under the turnout that allows access to the decoder and the switch motor, but you need to be sure it is the exact final position of that turnout !

Just btw; a hole allowing access to C Track switch motors is also a necessity on a permanent layout

There can be no problem as long as the cut-off switches are not bridged.

How hot can the turnout motors get in 0.4 seconds? So hot that it leads to self destruction?

Can they survive if a child presses the button on the switch panel for 1000 ms or even more?