Never assume the information is correct. But isn't that what troubleshooting is all about? Gathering all the information and narrowing down the issue? Yes, yes it is but sometimes that information can lead you away from the actual problem. Let me explain. The setup: I have 4 T-Trak modules that make up a stub ended station, I think you all have seen it already. Of the 4 modules in this set only 3 have the station tracks so we will just forget about the first module. From here on there is the Ladder module, (self explanitory), the Extension module (just 6 tracks going from one end to the other) and the End module which has the 4 station tracks terminate and the 2 mainlines pass through. The mainline tracks were not an issue in this case so we will ignore them moving forward. There is a control box that has rocker switches that apply power to the 4 station tracks, this plugs into a pigtail from under the Ladder module. There are also push buttons on this box that activate the DS64s to throw the various switches, these were not part of the issue and thus will also be ignored. There are jumper cables running under the modules to tie power into each leg of the station tracks and not have to rely on power through the one module. These jumpers are arranged so that if the Extension module is absent the End and Ladder module will still be able to connect underneath. Intended Operation: These modules were designed to be able to cut power to the station tracks to allow DC trains to be run on the red line, or remain parked while another train (DC or DCC) runs. To get a train moving you simply align the proper switches and flip the rocker switch to power the track the desired train is on. In DCC mode you can have all 4 tracks powered at once or cut power to any or all of them via the control box. In DCC mode you can access both mainlines through a cross over, but in DC mode only the Red line will have access to the Station. The Problem: I discovered that in DC mode tracks 1 and 4 were tied together as were tracks 2 and 3. If I turned on track 1, even with the power switch off the train on track 4 would also move. Same was true visa-versa. The other 2 tracks operated exactly the same way. This wasn't an issue in DCC mode, everything worked as expected. Temporary Solution: During the show I unplugged the jumpers underneath at the Ladder Module and the modules operated as intended. This told me there was a crossed connection somewhere (ie a short) and I needed to find it. Troubleshooting Steps: 1. I checked that each plug was assembled correctly and all wires matched up. Good to Go. 2. Checked that there was no shorts in any of the plugs. Good to Go. 3. Checked there were no shorts in the switch box. Good to Go. 4. Checked that the switches only turned on the desired track. Good to Go. 5. Plugged in each jumper and checked for shorts, (modules not connected) Good to Go. So far everything looks good, and I should not be having my issue. So I decide to build the set together including the first module (just in case) and see if the problem arises. Yes it does! OK so when everything is assembled there is an issue. 6. Unplug just the End module and test again. No Joy. 7. Unplug the Extension module. Good to Go. Problem goes away just as it did at the show. 8. Remove Extension module and reconnect jumpers. No Joy, problem returns. Common denominator here is the Ladder module. At this point I test and test all the connections on the ladder module and everything is good. But how? When it is plugged into the other modules either together or apart the issue come up. I double check my connections again on the Extension and End modules and everything lines up. If you have read this far, Thank you, I will be getting to the solution here in a second. This is the part where the information sometimes lies. All the information was telling me the issue was in the Ladder module. The problem happened only when I plugged the other modules into it. Everything on the Extension and End module matched up... and that is where the problem actually was. My labels for which track was which was incorrect on the Extension and End modules and they were exactly the same. This is why they were leading me to believe the issue was the Ladder module. My information written under the module was bad, and thus it took me to look at the good module as being the bad module. From the underside of the module I rely on the notes I write as it is difficult to see both sides at the same time. A simple error when I was building the modules caused me a couple hours of scratching my head. The issue didn't happen the first couple of times using these modules as I used them in only DCC mode. It wasn't until I used the unique feature I designed into these modules that I had an issue. The moral of the story here is "Don't believe everything you see... Test... Test... Test... Question everything, assume nothing."
A big part of my recently-retired-from day job was failure investigation. For each and every one of these endeavors, my initial surmise regarding root cause was ALWAYS wrong. So, yup, test, measure, test, measure... and stay away from relying on intuition.
One of the fellas that taught me troubleshooting as a Naval and then Locomotive electrician said that the best troubleshooters were always the "Laziest" ones. There's a problem? Yup. Get all, ALL, the symptoms. Analyze those against the wiring plans, and against whatever event just occurred. Then go looking at the possible causes, and never assume you have any idea what is the problem! Was a tough lesson to work out, but it ended up he was right, of course. Glad you solved the problem!
When I served in the Navy I was an Aviation Electronics Tech (AT) and I hung around an older civilian we had working in our shop. He taught me how to read the software for the test bench, and to read schematics. I was able to pinpoint the failure of a module down to the component most of the time. My fellow shipmates were more of the swap-and-see type technicians. They would see what the failure callout was on the screen and order that part. If it worked great, but if it failed, they just went to the next callout. If they ran out of call outs they gave up. I would sometimes step in and work the problem through to the bad component. Sometimes that component was the test bench itself. If you seen me working on the HUD or any other module of the F-14D’s radar most of the time I had at least 3 binders out and I would be studying the flow charts and schematics to get an understanding of what’s failed. I guess I was being lazy for just sitting there reading… lol.
And I bet you understood more about that HUD and F14D than most techs ever would! When did you serve? Which airwing and carrier? I was on CVN-70 from 83-87, down in the reactor rooms.
I was at Naval Station Oceana AIMD for the first part of my career and attached to the USS Stennis CVN-74, then Norfolk AIMD and lastly the USS Truman CVN-75. I was in from 2001 to 2006. My rack was right under the flight deck on both ships at the catapults on the Stennis and under the wires on the Truman.
I need to scan in my pics of when we (CG59) used to unrep with the Abraham Lincoln. All the way up on our 04 level and we were just above the hanger deck but still below the flight deck lol. Kind of made me feel like we were on a raft. My Uncle who was a chemist for Sante Fe came to see me when I graduated boot camp and when that was done we went down to Coronado/32nd street to see the ships. When he saw the carrier moored up (I don't remember which one) I remember him saying "I understand displacement but seeing something that big float doesn't seem possible".
