Control problem with AIU controlling Fastrack Switch

Possible the relay in the AIU failed. Do you have spare AIU outputs? Perhaps you can connect to another point.

Can you take a short jumper wire or even a paper clip and momentarily touch the AIU SW port terminals between IN and 1, then IN and 2...with your turnout hooked up of course.

I have  the same thing going with one of my AIU relays. If I work the remote buttons several times I can get it the throw. I guessing a manufacturing defect is the culprit. Fortunately this switch is on a spur and not used all that much.

@milwrd posted:

I have  the same thing going with one of my AIU relays. If I work the remote buttons several times I can get it the throw. I guessing a manufacturing defect is the culprit. Fortunately this switch is on a spur and not used all the much.

Out of curiosity, does it require multiple button presses in both directions (Straight-Diverge vs. Diverge-Straight)?  For example, if you swap the wires going to the #1 and #2 screw terminals for that particular SW port, does the turnout now require multiple button presses in the other direction?  That is, if the problem remains in the same direction, it could be a sticky turnout.

Not so obvious but there are 2 relays per SW port in the AIU.  One relay fires for exactly 0.5 seconds in one direction.  The other relay fires for exactly 0.5 seconds in the other direction.  I can understand one relay failing...but for both relays in a pair to fail would be quite the coincidence!

An AIU relay can be replaced though it does require a modicum of soldering skill.  Simple visual inspection of the board and a meter can identify which relay(s) correspond to a given SW port.  The relays are widely available for maybe a couple bucks a piece.

Stan, I think you're on to something. I was down working on the layout this afternoon and took a break to check the forum. After reading your post I went down to give your idea a try. It does indeed only have the problem in one direction. After a half dozen attempts it threw in both directions intermittently. With the switch in the direction at issue I repeatedly cycled the button and after ten or so it threw in both directions without a problem. I don't however think it's the switch that's the issue. I'm using Ross switches with Tortoise machines, so I believe you would hear the Tortoise moving even if the switch was sticking.

And yes, there certainly is a bunch of relays in those AIU's. I found this out when I opened up my AIU's (three in my case) and bridged all of the "IN" terminals to one another for a little cleaner looking installation.

@milwrd posted:

...I'm using Ross switches with Tortoise machines, so I believe you would hear the Tortoise moving even if the switch was sticking. 

What sits between the AIU and the Tortoise motor?  Since the AIU only provides a 1/2 sec pulse, you'd need a latching relay or the electronic equivalent such as the Circuitron TC-3 (which I recently learned about in this OGR thread).  Point being, I'm having a hard time picturing how repeated pulses from the AIU SW port helps to coax the Tortoise along.  That is, the first button press sends a 1/2 sec pulse from the AIU to the Tortoise; this should latch the Tortoise electronics to the commanded direction.  Additional button presses (i.e., additional 1/2 sec pulses from the AIU) should not provide additional energy...very curious.  

A while back you were kind enough to walk me through wiring up some of those latching relays from Asia.

Thanks again.

Ahh, I recall that.  Since those are SPDT (not DPDT) relays, you are using Accessory AC voltage and 2 diodes to steer + or - pulses to the Tortoise motor?

Still puzzled though.  After pressing the button ONCE to change Tortoise position, the appropriate latching relay has been set to the correct position.  As I recall, that relay module should hold the "last" commanded relay in the correct position.  Additional or repeated button presses will not change the relay position.  As long as you don't send intervening commands to latch a different relay, I don't understand why repeated button presses add power or voltage to move the motor along.  Though I suppose if it's working acceptably, we can let that sleeping dog lie...

I am using the AIU switch ports and all is working great. At issue is that when pushing the button on the remote (the straight arrow in this case) it wouldn't always trip the latching relay. I can hear the relay in the AIU clicking but won't engage the latching relay. After repeatedly hitting the button I can get it to go. Kind of strange that I can hear it trying but doesn't make the connection every time.

OK - I get it now!  So it's the latching-relay module that does not reliably detect the apparent momentary relay click in the AIU.  I say "apparent" because you hear the click but we don't really know if an electrical closure occurred.  All bark and no bite!   

Obviously you can see if the latching-relay module electrically detected the AIU's 1/2-second relay closure because the corresponding LED on one of the relays will light accordingly.

OK.  Well, I guess if comes down to one of those life-altering decisions of whether it's worth the bother to isolate the actual flakey relay and changing it.  As mentioned, that relay is a common part that sells for a couple bucks; I don't want to think about how much it would cost to get it professionally repaired plus two-way shipping!

Hard to say Stan. Is it the relay in the AIU or the one in the latching bank? One of these days I'll get the meter out and check the AIU port out.

The layout is for the most part up and running so I'm in to the more visual aspects for the time being. As I said further up in the conversation, it's on a switch that's not going to be used all that much so I'm not going to lose any sleep over it.

Stay safe

Thank you all for your responses and suggestions.  I jumpered between IN and 1 and then 2 on the AIU.  The switch worked in both cases.  I then wired the switch to a spare circuit on AIU and the switch now operates properly.

So to summarize for anyone who stumbles across this via a Search, the closest exit is to use a spare AIU SW port.  Move the 3 wires over and use the DCS remote to re-address the turnout to the new SW port.

That said, for anyone in lockdown with nothing better to do on a rainy afternoon, here's a photo showing the bottom of the AIU circuit board.  Each relay has 5 pins.  Once you identify the flakey relay (e.g., the Straight relay on SW4), follow the printed-wire traces from the 3-position screw terminal connector to the specific relay.  Again, each SW port has a unique relay that closes for Straight, and a separate relay for Diverge.

Read the part number off the relay; in my case: Omron G5LA-14 12VDC.  These are easy to find for less than $2 a piece.  It appears that the G5LE series has replaced the G5LA series.  I attached both datasheets; it's left to the student to determine if there were any material changes. 

And I suppose it would be curious to cut open the "sealed" relay and examine the contacts.  That is, if you are hearing the relay click on and off for 1/2 sec, then I'd think the contacts will be dis-figured. 

It's way on the back burner for me, but I too would like to know what the inter workings of the relays look like and the possible defect in this case. I'm guessing there not to much different then automobile relays in the sense that there is a thin piece of tempered steel with a set of contacts on either side that flips right or left and than centers itself for the next time activation is required.

As it turns out for me, using a different switch port is a no go unless I add another AIU. 30 ports / 30 switches.

As always, I appreciate your knowledge and insight with electronics. Between you and GRJ you both have helped me keep the magic smoke at bay.