After changing the power delivery wires from transformers to TIU inputs to 12 ga stranded on four track circuits (TIU inputs), the next time I tried to run trains this happened: With three different locomotives, two diesel (both ERRCo conversions that worked perfectly before) and one steam (Legacy).  Both diesels start up fine, respond to horn and bell commands, but when throttle is advanced they move minimally and then “die”, go silent and stop moving.  Turn the speed knob back down and wait a few seconds, and sounds return as well as response to commands, but same result with speed knob advanced (“die.”). The Legacy steamer doesn’t even start up, no response to “Engine 25” at all.  Re-set its engine number to make sure not “forgotten,” but that wasn’t the problem.  This all was with an older Legacy base that to date had been fine.  I tried a Legacy 1-L system and then an old TMCC system, and the behavior is the same with all.  This is with GRJ’s TMCC signal “buffer” boosting signal maximally, too.

Color me puzzled.  What to do, what to test?  I have a signal test circuit to use with a VOM, so with advice can look at signal in whatever location needed, I think.

Thanks.  Hope all of you remain safe and not needing to expose yourselves unnecessarily to the pandemic virus.

Don

Original Post

Did you try going back to the original wires you had between the transformer and TIU? Just curious to know if the problem stayed. Also curious as to what wires you used before changing to 12 gauge stranded. 

If you take the engines to the bench and run them on a test track or rollers, do they work there?  If that's not an option, consider another layout for a test.

Yes, on the test track things behave normally.  What changed for the layout was from 2 track circuits with about 20 feet each of 14 gauge wire on the common side between transformer and 2 TIU inputs, to 4 circuits (two newly connected) with about 20 feet each of 12 gauge wire on common side transformer to TIU.  So as you experts point out, some added capacitative load for the signal compared to before, but this still is not close to the mass of copper wire on the common side of some of the truly huge layouts where things work, especially with your buffer added as here.

Nothing you've said, taken literally, explains why both TMCC and DCS would quit working.  There has to be something else in play.

TMCC failing is especially odd as normally very little you do with the power would affect it.  Nothing on the input side of the TIU should have affected the TIU or TMCC/Legacy signals, so that doesn't explain anything.

I would double check the one wire from the Legacy Base is tight and connected to the output side of the TIU. I would also make sure the commons on the output side are connected. 

Yes, Marty, confirmed on both counts, for all three trials of Legacy, Legacy 1-L and TMCC systems.

gunrunnerjohn posted:

Nothing you've said, taken literally, explains why both TMCC and DCS would quit working.  There has to be something else in play.

TMCC failing is especially odd as normally very little you do with the power would affect it.  Nothing on the input side of the TIU should have affected the TIU or TMCC/Legacy signals, so that doesn't explain anything.

 Clarification: I did not mean to imply that DCS function changed, have not even tried that.  Will do so just in case something changed, but for it to be involving all 4 channels seems unlikely.  The Legacy/TMCC signal connection has always been to one wire output at a barrier strip just inches from the TIU output, from one of the TIU channels, so it reaches layout by that one common wire.  That didn’t change.

Hudson J1e posted:

Also you said transformers (plural). Is it possible the transformers are now out-of-phase?

Good question.  No, they are not: have attended to that long time ago.

gunrunnerjohn posted:

Did you test the command base on the bench to see if that has changed?

Used Legacy 1-L set on test track with normal loco function, yes.

I have read in other threads on DCS forum that some clubs feed TMCC signal to each  TIU output.  That would shorten signal path for those blocks not now getting signal directly (meaning all but the one).  Will try that with a soldered wire harness to deliver signal to all four outputs, next.  If that doesn't solve, plan to remove all but one of the new 12 gauge common power feed wires from system and try one block that way.  The new wires are the last thing changed.  Thanks for the ideas, please keep them coming.

 

Is the TMCC/Legacy/1-L base drawing power directly from an outlet?  Is that outlet working?  Or are they plugged into a surge protector, which could also be either defective or killing the signal (not a continuous ground)?  This has to be something in the power or signal pathway to the layout since everything works fine from a (presumably) different outlet and signal pathway to the test track.  Would replace the wire going from the base to the track just in case it is broken or otherwise dysfunctional.  Wires break .

Thanks.  All of those known OK, wire from base just replaced yesterday when repositioning devices.  Will report next results of wire harness to all TIU outputs and then, if necessary, removal of all but of the one new common wires to blocks.

cnwdon posted:
gunrunnerjohn posted:

Did you test the command base on the bench to see if that has changed?

Used Legacy 1-L set on test track with normal loco function, yes.

Would think that means something is incorrect with your new wiring set up.

Bingo, BobbyD!  We have found the enemy and he is us!  The PSX1-AC rapid breaker circuits that went in just before the new wiring need a jumper to set the trip current higher than 4.8 amps.  I forgot the jumpers in my zeal to get the boards installed and all pretty.  Tomorrow will install them and suspect I’ll be reporting no problems.  Sorry to waste everyone’s time speculating! 

gunrunnerjohn posted:

Why would the current setting cause issues with the TMCC signal?

With no jumpers, the PSX1-AC trips at 4.8 amps/ just low enough to produce what we were seeing.  It wasn't signal loss, it was power cutoff and then with speed dialed back and less current through motors, it resets itself and things come back to life---I think.  I'm rewiring with the jumpers added to make it a 12.2 amp threshold today, expect this will be the cure.  Will report 

OK, that behavior would nix that product from ever being used by me!  When I have an overload that trips a breaker, I want it to stay tripped until I fix the reason for the trip.  Having it banging the short with continuous on/off cycles is not something I put up with!

The PSX-ACs are configurable for either manual or automatic reset. I have mine set for manual reset with a reset button mounted in the layout table fascia by the power cart. I don't want things coming back on until I'm ready either.  The PSXs also have lots of other configurations, alarms, outputs for LED indications, etc.

Last edited by rtr12

Hmm. Seems we could of eliminated the Legacy setup first thing if we knew the power was dropping out. 

Yep, that was a rather large clue!  It would have been nice to know about the PCX-AC units that were added as well, that's not exactly a "small" change.

Ah, well, the symptoms always make perfect sense once the diagnosis is figured out.  I overlooked the fact that I hadn't run trains since adding the PSX1-AC's to the system, before adding the new 12 gauge power feed wires (seen entering from the right).  All wired now with jumper on each PSX1-AC so trips at 12.2, not 4.8 amps.  The starting current for the 3 prewar-style or 4 DC can motors in the two diesel lashups in question just touched that 4.8 amps.  The reset is not instantaneous, there is time to turn things off.  After reducing motor current, it took a fair bit of time for the power to resume.  Since the setup is hanging from the ceiling for better radio signal from remotes around the basement to bases (TMCC and DCS), the work is overhead and the neck only does that for a while before needing a break.  Finally all tidy to my satisfaction.  Your TMCC DM Buffer is nicely displayed, GRJ.  Thanks for speculating with me while I got another flat spot on my forehead to add to the collection there 

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