Help Needed - AIU won’t work properly

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Help Needed - AIU won’t work properly Sept 17, 2019 20:48:17 GMT

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Post by Deleted on Sept 17, 2019 20:48:17 GMT

Have been installing an AIU (MTH relay control for turnouts and accessories). Actually, it installs quite easily. Hook up one cord, add it to the system, install the two accessory wires, in our case a yard light, program the remote, and PRESTO........... uh, the relays click on and off just fine but no light.

Does anyone have any ideas other than send it back? Reading Barry’s book doesn’t offer enlightenment. I am trying something that should be really simple before getting into Tortoise controls with additional relays.

Thanks

Bill Webb

Country Joe
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Help Needed - AIU won’t work properly Sept 17, 2019 21:35:01 GMT

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Post by Country Joe on Sept 17, 2019 21:35:01 GMT

Bill, I just looked at the instructions for the AIU and for a two wire connection one wire (red) goes from the transformer to the accessory and one goes from the transformer (black) to the AIU input and then from the AIU output to the accessory. Is this the way you wired it? Other than a wiring mistake I don't see what could be wrong.

Last Edit: Sept 17, 2019 21:35:41 GMT by Country Joe

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twincities
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Help Needed - AIU won’t work properly Sept 17, 2019 21:46:12 GMT

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Post by twincities on Sept 17, 2019 21:46:12 GMT

okay first off I am no means an electronics genius but here goes, so the AIU does send signal to relay and I think you mean you hear the relays contacts being energized correct? so if this relay has 2 sets of 4 terminal screws you need to add power to the coil side of one of those 4 screw terminals so that when relay energizes contacts it will send the power from coil side to one of the 4 terminals opposite of coil side and your yard light allowing it to light up you also need a common connection to yard light that should complete the circuit?.

one way to find the powered terminals on side away from relay coil is with a ohm meter when power is applied so contacts allow power to flow through it one of those terminals opposite the coil side will show 12 volts or whatever voltage your connected to that is the positive terminal to connect from relay to yard light and the common wire can go direct to the yard light from your power source my rule of thumb is no worky then power is neither getting to the item nor returning back to power supply.

hope this helps you out last piece of sound advice I always make a diagram of what wires go where to make it all work that way you can apply to other electric connections and also know how you wired it for trouble shooting later.

Last Edit: Sept 17, 2019 21:51:40 GMT by twincities

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Help Needed - AIU won’t work properly Sept 18, 2019 12:36:50 GMT

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Post by Deleted on Sept 18, 2019 12:36:50 GMT

Thanks guys for the help. You are both correct (I think).

The AIU is an MTH product and everything is wired to a board. There are about thirty relays on the board.

The only screws that’s are available are the ones where you attach the accessory/turnout wires. I ran the positive to the middle terminal three and the wire from the light to the next terminal. Push the remote and the relay clicks but there is no power. If I touch my second wire to the first, the light comes on so there is a problem with the relay not working. Each accessory has three places where wires can attach and I have tried all three... nothing.

I also set up another set of accessory terminals and got the same thing. Have also tried resetting by turning everything off, deleting and readding, etc.

This is as simple a circuit as we can get.

I read in Barry’s book that a bad TIU can cause a problem. I have a spare and my next option appears to be to hook it up. This time I am going to do it on my desk where I have a transformer and there will be nothing else that can interfere.

I will advise. First I have to go to Norfolk about some tile that came in yesterday.

twincities
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Help Needed - AIU won’t work properly Sept 18, 2019 19:07:07 GMT

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Post by twincities on Sept 18, 2019 19:07:07 GMT

AIU_Tsw.pdf (47.07 KB)

link above shows a diagram on how to wire power source and AIU to a Tortoise switch machine. the one thing lacking is they do not mention if the power source is ac or dc! maybe someone here knows if the aiu cares if power is coming from a dc power pack?

Last Edit: Sept 18, 2019 19:16:26 GMT by twincities

twincities
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Help Needed - AIU won’t work properly Sept 18, 2019 19:22:32 GMT

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Post by twincities on Sept 18, 2019 19:22:32 GMT

Sept 18, 2019 12:36:50 GMT @oldhokie70 said:

Thanks guys for the help. You are both correct (I think).

The AIU is an MTH product and everything is wired to a board. There are about thirty relays on the board.

The only screws that’s are available are the ones where you attach the accessory/turnout wires. I ran the positive to the middle terminal three and the wire from the light to the next terminal. Push the remote and the relay clicks but there is no power. If I touch my second wire to the first, the light comes on so there is a problem with the relay not working. Each accessory has three places where wires can attach and I have tried all three... nothing.

I also set up another set of accessory terminals and got the same thing. Have also tried resetting by turning everything off, deleting and readding, etc.

This is as simple a circuit as we can get.

I read in Barry’s book that a bad TIU can cause a problem. I have a spare and my next option appears to be to hook it up. This time I am going to do it on my desk where I have a transformer and there will be nothing else that can interfere.

I will advise. First I have to go to Norfolk about some tile that came in yesterday.

from what I seen online a power wire goes to middle terminal on aiu then terminals 1and 2 are connected together and run to item needing powered the common wire goes directly to the item being powered to turn on or in simplicity I call it making a circle power goes in and returns to power source. best I can explain it. I have to ask are you only using the AIU to power the yard light or do you in fact have wires going to the relays coil wire only? if only coil powered that is why yard light not working as relay needs a wire on each side of contacts so power can pass through the relay to the yard light and then the yard light needs a common wire connected to the transformers common terminal.

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Help Needed - AIU won’t work properly Sept 18, 2019 20:50:39 GMT

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Post by Deleted on Sept 18, 2019 20:50:39 GMT

In March I asked about how to handle a Tortoise on OGR and three people responded. They were very helpful and really know their stuff. I have the components ready to start with that.

To get to that stage, I needed to connect and test the AIU. A one light connection seemed to be the best solution and everything was at hand.

Barry refers to this circuit as a “Single function accessory and shows what you describe and what I hooked up:

Black from transformer to the center “in” connection on the AIU

Red from the transformer to the light.

Wire from the light to the left “1” on the AIU.

I searched for AIU problems on OGR and found a lot of info but nothing exactly like this. But often the solution to a problem was to connect components that you know work and test it out to be sure that everything is okay. Then substitute; if the new component doesn’t work, send it to MTH.

In AM I plan to do this with another transformer, TIU, and the same AIU since it is all that I have. If it doesn’t work, I am picking up two more AIUs at York.

Thanks for your help. My guess is that there is a board problem. I have seen this mentioned on OGR.

twincities
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Help Needed - AIU won’t work properly Sept 18, 2019 21:16:07 GMT

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Post by twincities on Sept 18, 2019 21:16:07 GMT

Sept 18, 2019 20:50:39 GMT @oldhokie70 said:

In March I asked about how to handle a Tortoise on OGR and three people responded. They were very helpful and really know their stuff. I have the components ready to start with that.

To get to that stage, I needed to connect and test the AIU. A one light connection seemed to be the best solution and everything was at hand.

Barry refers to this circuit as a “Single function accessory and shows what you describe and what I hooked up:

Black from transformer to the center “in” connection on the AIU

Red from the transformer to the light.

Wire from the light to the left “1” on the AIU.

I searched for AIU problems on OGR and found a lot of info but nothing exactly like this. But often the solution to a problem was to connect components that you know work and test it out to be sure that everything is okay. Then substitute; if the new component doesn’t work, send it to MTH.

In AM I plan to do this with another transformer, TIU, and the same AIU since it is all that I have. If it doesn’t work, I am picking up two more AIUs at York.

Thanks for your help. My guess is that there is a board problem. I have seen this mentioned on OGR.

if you want to check if AIU is the issue could you not use an ohm meter connected to wire from aiu and other common wire to see if you have power heading to the yard light? or is it possibly the relay inside the aiu that is bad? not owning one am guessing at best as to troubleshooting it. on my 18th layout I have 2 tortoise switches powered from a toggle switch all the rest are close at hand and utilize caboose industries hand throws simplicity only component to fail is the human not throwing it lol ! I hope it all works out for you so you can get it all working as you want.