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I have 2 TIUs (a Rev G and a Rev L), 2 AUIs, and 2 TUI/AIU interface cables. I've successfully had the G and one of the AUIs work in the past. The other AUI is one I bought maybe 5 years ago, but never used.

Both TIUs are set to Address 1 (1 blink, verified), but powered only one TIU at a time. For each TIU, I tried both AIUs and both cables in all possible combinations. The cable is always connected to the TIU at the AIU INPUT port and to the AUI at the TIU INPUT port, per Barry's book. The TIUs had nothing other than AUX power connected to them. When I hit READ, I always find TIU1 as expected) but no AIUs. What am I doing wrong? I'm having a very hard time believing that both TIUs, both cables, and both AUIs are bad.

Chris

LVHR

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Robert,

Thanks, but that will make no difference, as only 1 TIU is powered at a time. The remote is programmed for TIU Address 1, so any TIU with that address will show. Once I have things ironed out, I'll change one of the TIU addresses. I will check the firmware, but I'm fairly certain that both are at 6.1.

Edit: I chcked the TIU firmware version. The Rev L is 6.00 and the Rev G is 4.10 (ouch!). I'll look into getting the G up to snuff.

Chris

LVHR

Last edited by lehighline

The cables are what came with the AIUs. When I lay each one out flat, the plastic lock tabs are on the same side. That means they were properly assembled.

BTW John, what is the longest cable I can place between the TIU and AIU and still have the AIU function? Can I get away with 25’?

Chris

LVHR

Go run a train or something, but stop being a jerk.

Vern,  We all have known this type of individual throughout our lives… narcissistic, vengeful and socially inept.  The good news is that they eventually discover and gravitate to other forums where this type of behavior is not only looked upon favorably but rejoiced and reveled in by their brethren.  Even better, none have any real friends… and, they eventually eat each other.

One aspect of this topic and extremely relevant to @gunrunnerjohn's excellent diagram of the AIU connector 12V pinout is that many folks, myself included, using relays have run into the power problem when you energize an entire bank of relays. As an example, at our club, we use several time delay relay modules for accessories in our amusement park area. Because we powered those timer relay modules off of our accessory power bus, there is a small 12V switching regulator module. We kept adding more buttons, more relays, and visitors would just go down the line of 12 buttons and press them all on, and so the current of holding that many relays in the active state would kick out this regulator on thermal. The solution was a bigger regulator, but also break up the multiple banks of relay timers, and put them on individual regulators.

Well, where this story has a parallel to typical train usage cases, you might wiring wise make sense to put the AIU nearest the accessories being controlled rather than a whole bunch of wire some distance from each accessory to the AIU. The problem is, then this thin AIU cable wiring is carrying that 12V from the TIU to your TIU, and depending on how many relays are active at any given time, the amount of current the AIU draws, and more importantly,the voltage drop across the distance of the cable. So, on long cable runs, it might be highly desirable to provide a local 12V regulated DC source at the AIU, especially one when a lot of the relays spend much of the time activated all at the same time.

And let's be honest- even Lionel ran into a similar issue with the LCS cabling system and a single power source. That's why only through tech support, you can order the special PDI cable PCB that allows you to inject a local source into that system. Many LCS modules are just banks of relays and the more relays active at a given time and longer cable distance, the worse the problem becomes. https://ogrforum.ogaugerr.com/...itations-through-pdi

Last edited by Vernon Barry

Another solution here is to use heavier wire for long runs.  There's nothing in the rulebook that says you have to use the wimpy 26ga or 28ga flat cable for long runs to AIU boxes.  You can run 18ga thermostat wire for long runs and just splice in 6P6C connectors on a little PCB to mate to AIU with the short 1ft or 3ft cables.  It would be really easy to hack out a PCB that has provisions for this connector and six soldered connections to run the long extensions.

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Last edited by gunrunnerjohn

Surprise! Things may have sorted themselves out a little tonight!

I went to the layout with the intent of taking pictures of the TIU, AIU and remote with message. Random choice as to which AUI and cable. The TIU is the Rev L with 6.1 firmware. Lo and behold, the connection worked! Don't ask me why, I have no clue. I connected everything the same as always.

IMG_0577



So with the connection working, I decided to add the second AIU to the mix. Failure!

IMG_0578



The second cable is marked with orange tape. I swapped connections, and only  one  AIU was found.

IMG_0580

Running the unmarked cable to the second AIU was a success.

So at this point, I'm reasonably certain I have a bad AIU cable (the one with orange tape.) I ordered new cables and some adapters this morning, so I'll have to wait for them to arrive to finish testing. But things are looking up!

Chris

LVHR

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Last edited by lehighline

Now I'm getting frustrated!

A package arrived today with 2 2' cables with 6 wire reversed connectors. Reversed connectors are the correct configuration for the TIU/AIU cable. I pulled the existing (working) cable off the TIU/AIU and connected each of the new cables in turn. Success! I then did the same with the second AIU (NOT daisy chained). Again, success! So now I know I have 3 good cables. Next, I tryed to connect both AIUs to the TIU(daisy chain). This resulted in failure to find the second AIU. I played with combinations of all 3 cables and both AIUs. No matter what I did, I always found 1 TIU and only 1 AIU. At this point, I'm thinking both AIU OUT ports on the AIUs are bad. Maybe they are dirty, as I've never used them prior to now.  But honestly, why should they be dirty?

But the saga continues: I went back to the suspected bad (orange tag) cable. As expected, the connection failed. I figured I had confirmed a bad cable. BUUUUUT..... when I went back to the 3 good cables, NONE of them worked between the TIU and either AIU! So now I don't know what to believe nor what to do. Something is clearly wrong and intermittent. It's driving me nuts!

Chris

LVHR

Time for an update. I’m back from a week vacation trip. My parts order arrived, so I’ve been able to conduct some testing. I also went scrounging and scared up 2 more TIUs. I don’t need 4 TIUs for this layout, but that’s a story for another time. The TIUs are Rev G, Rev H, Rev L (T1), and Rev L (T2). In my order was a DB9/USB adapter cable, so I could perform firmware upgrades. All 4 TIUs are now running the latest version, Ver 6.1.

I also ordered a pair of short (2’) reverse wired 6 pin cables, some 6 pin ports, and a pair of 6 pin adapter plugs with screw connectors so I can attach heavier gauge wire for longer runs.

All 4 cables were checked first. I connected a port to each end and put an ohm meter across the pins, looking for continuity and lack of cross talk. Cables C1, C2, C3 all passed. C4 did not, as one end would not seat in the port. The failure was expected, since this cable has proved problematic in the past. It appears that the crimp was not performed correctly, as all the pins are raised, preventing correct seating.

Test 1

Next, I decided to check the voltage out of the TIU AIU INPUT port. This is where my first surprise hit. I wanted to use the 6 pin screw adapter plugs and put the meter probes on the screw heads. But neither adapter would lock in position. At this point I shifted and tried both adapters in all 4 TUIs and in both ports of both AIUs. The plugs refused to lock into position. Then I tried both adapters in the 6pin ports I used to test the cables. Both adapters locked correctly with any combination I tried.

IMG_0798

Since the good cables have all shown no issues with any of the TIU or AIU ports, I conclude something is amiss with the adapters.

My work around to this was to connect cable C1 to a TIU and a port to the other end. Then I could put voltmeter leads on the appropriate pins. This led to my second surprise: The pinout voltage and pin numbers do not match the diagram GRJ posted previously.

IMG_0800

The diagram says there should be a 12VDC potential between pins 3 and 5. I checked both the pins coming from the TIU, and then connected an AIU (A1) and another cable (C2) with a port on the end of that. TIUs G, H, and L1 were tested. In all cases, I found 0 VDC between pins 3 and 5. I DID find 5VDC between pins 3 and 4. The 5VDC shows on the output from the TIU, and the output from the AIU. I did not test other combinations.

Does anyone have information on what should be on the pinouts other that this diagram?

Chris

LVHR

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How were you powering the TIU when performing the test? Hopefully via a 12V or higher adapter plugged into the TIU aux port.

I just tried it both ways- allowing the TIU to be powered via USB connection from the wifi and then with 12V into the aux in. I then in turn lost the 12V out of the AIU connector when the TIU is only 5V powered, and it returns when I provide proper aux power.

Vernon,

Thanks for chiming in! I've been using a multitap Radio Shack wall wort in AUX power for forever. It has a slider switch for setting the voltage. I verified that it was set for 12v and put the voltmeter across the barrel. I'm getting 15VDC. That should be fine, correct?

I'm thinking about this and I may not have the pins labeled/tested correctly. Based on your pictures and annotations, when the port is installed on the PCB, the locking tab is down. That puts pin 1 in the far right side, correct? So if I flip it upside down by rotating the connection away from me, pin 1 is still on the far right. There are 2 rows of 3 pins each. The pin in the back right is pin1. Moving to the left,  the back row is 1,3,5 and the front row from the right is 2,4,6. Correct? If so, I should be testing the middle and left pins in the back row for 12 VDC. Let's see what I find.

John, Thanks for the help. I'll get to the bottom of this eventually!

Chris

LVHR

This thread is due for an update.

I took John up on his offer and paid him a visit. After exhaustive testing, we verified that I have a bad cable, AND that BOTH AIUs have issues. We also concluded that the failure mode was different for each one. No wonder I could not get anywhere!

Since published documentation on AIUs is sparse (understatement!), I contacted MTH Service through their website. Eventually I reached a MTH service tech who could guide me through the troubleshooting process. So with John telling me what to look for, and me reporting the symptoms to MTH, I was able to identify several bad/blown chips on the circuit boards. Unfortunately, I now have more experiece than I really ever wanted when it comes to replacing DIP chips!  A big thank you to GRJ for helping identify and souce the necessary chips. So now I had 2 AIUs that could properly daisy chain.

I picked up a third AIU at the Fall York meet and added that to the mix while I was waiting for some parts to show up. With the parts installed, the 3 AIUs properly daisey chained. But now the relays would not fire correctly. The MTH people identified this as a software bug that is specific to RevL TIUs. The MTH people were able to provide me with the proper updates, which I installed. So at this point, I now have 3 properly functioning AIUs, and 2 updated Rev L TIUs.

The last piece of the puzzle is that the third AIU is located some distance from the the first 2 AIUs. I'm waiting on a long cable (ordered). With any luck, all will work as advertised and I can put this issue behind me.

So a big "THANK YOU!" to the folks at MTH and also GRJ for helping me through this mess. I appreciate it!

Chris

LVHR

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