Atlas O Switches with DCS/AIU - Problem with Occasional Continuous Power to switch motor

There is a good bit of forum information on the Atlas 6924 relay board.  One of the primary functions of the board was to inhibit switch motor burnout, or as you have described, continuous power to a momentary motor.   If you hold the Switch button on the Handheld remote a bit too long it may cycle through two or more momentary power to the switch motor.

Recent thread    Click on the underlined phrase to link.

Reference Non-derail wiring

Reference Power routing.

Thank you!  I did take a look at those threads previously, but am curious as to why a momentary relay switch would still be providing power to the switch motor - continuously, not just a hit of the button a couple times.   Thanks again!

DonnieD posted:

Thank you!  I did take a look at those threads previously, but am curious as to why a momentary relay switch would still be providing power to the switch motor - continuously, not just a hit of the button a couple times.   Thanks again!

If you hold the Switch button on the Handheld remote a bit too long, it may cycle through two, or more, momentary power to the switch motor.   That's the way it was with my Cab1 TMCC remote and the early IC Control modules that I used.  A couple of burned out switch motors prompted the install of the Atlas 6924 boards, which had built in time-out feature to back-up the momentary circuit design.   Not familiar with the AIU control though I do have a TIU.   Hopefully a DCS guru will chime in. 

Some hobbyist have switched to DZ1000 switch motors, that have limit switches built-in.

Best wishes, Mike CT.

Thanks, Mike.  I really appreciate your help and the information!   I called Atlas this morning and they were very helpful.  Basically,  the response was..."that happens occasionally" with these switch machines.  They are sending me a couple new switch machines to replace the ones that burned out.  I think my solution will be to connect the power source to a relay in order to turn on/off the power remotely when not using the switches.  It will create an extra step to throw a switch from the remote/iPad, but it will hopefully keep the from burning up (or burning my house down :-) ) until I can get a hold of 6924 boards.  

Thanks again!  Take care,

Donnie

I had this problem with Atlas switch machines using the AIU. I was told by a MTH repair tech to keep the telephone type wire that conects the TIU to the AIU to a minimum. ( I was using a six foot length for an AIU remote location). Once I shortened it by using the provided telephone cable that comes with the AIU, I never had another problem. That was 9 years ago and haven’t melted a switch machine since.

Jack brings up an interesting possibility.  When the stuck failure occurs do you hear the distinct pair of clicks from the AIU relay when it fires ON-then-OFF - sort of like a "tick" then a "tock"

The timing of the SW relay is performed in the TIU.  TIU sends ON to the relay (tick), waits exactly 1/2 sec, then sends OFF to relay (tock).  If there is some kind of intermittent/flakey communication issue in the cabling perhaps the OFF command is not reaching the AIU and the relay stays ON. 

Don't know if it's worth your time to do more experimentation but if it comes up again, you might listen to the AIU for the relay action.  If the relay does stick ON, if you quickly press the same function (Straight or Diverge) again, the TIU will again send ON, wait 1/2 sec, then send OFF.  This follow-up pair of commands might make it thru and clear the stuck-on condition; then blame can be established!

Thank you Jack and Stan.  I am using the TIU to AIU cable provided with the AIU.  I did "catch" the switch stuck in the on position again and tried reactivating the switch - I heard the AIU click on and off, but the switch remained on. I called Atlas this morning - they were very helpful.  Basically, I was told that "it happens" with these switches and that they would replaced the ones that burned up.   My temporary solution, until I can get a hold of the 6924 boards, is to put the power for the switches on a separate relay I have for track power and turn them on/off via the AIU.  It will be an extra step to throw a switch, but it will hopefully a save something from burning if I don't hear or catch one that is stuck on.  

Thanks again for your help.

DonnieD posted:

Thank you Jack and Stan.  I am using the TIU to AIU cable provided with the AIU.  I did "catch" the switch stuck in the on position again and tried reactivating the switch - I heard the AIU click on and off, but the switch remained on. I called Atlas this morning - they were very helpful.  Basically, I was told that "it happens" with these switches and that they would replaced the ones that burned up.   My temporary solution, until I can get a hold of the 6924 boards, is to put the power for the switches on a separate relay I have for track power and turn them on/off via the AIU.  It will be an extra step to throw a switch, but it will hopefully a save something from burning if I don't hear or catch one that is stuck on.  

Thanks again for your help.

 

A small inline fuse may help.   (1 amp probably more than enough)