F3 ABA went wild

Yes... Switch to Legacy / TMCC and get rid of that MTH junk.

NOW THAT'S FUNNY!!!!

I already have Legacy, 12 Legacy engines and several TMCC, but I am not giving up my MTH DCS engines. I have been running both systems concurrently without any issues for almost two years now. 

The problem I have now is with just the F3 ABA, and all I want to know is whether there is anything I can do before shipping them to be fixed.

Thanks for your help.

Alex

I did the same thing with my Marx train when I was six by way of an overly enthusiastic ignorance of speed limits. It's progress when manufacturers can do the same thing at ten times the cost with highly sophisticated electronics and now derailments are now automated to boot. I restored the trains progress by placing it back on the track, now we need a team of specialists with a university degree to do essentially, the same thing.

Top suspect for this failure is the encoder on the motor.  If it's not reading the striped tach wheel, that's the symptoms you experience.  I'd take a peek inside and see if that has become dislodged or a wire broken from the encoder board, that's happened to several I've seen.

Alex: What voltage are you applying to the TIU power terminals? For test purposes set it just high enough for the DCS system to operate. Then test you engines again. I agree that the tach reader may be the problem since it is the only way the DCS knows what speed to drive the motors.

Pro Hobby

Try the leading F unit on its own.

ALex,  If you want a faster turn around you may want to give me a shot.  If under warranty then I would send it to MTH.

If all the unit where full steam ahead, then as Chuck said you can test A unit by it self.  That has the tach.  I would also put the powered trail unit on the track by them selfs and power the track.  If they move the slave board FET has been shorted and they need to be repaired.

This does sound like a loss of tach signal.  So as soon as the engine is commanded to move, and it doesn't have the feedback the motor is turning (even though it is) the board will command more voltage to the motor.  Hence full speed.

It can be a bad sensor, faulty tach tape, damaged wire or the speed amp is damaged.  If the trail units act fine, then only the A unit would need to be sent.  G

John, Alan, Chuck, G -

I suspected the encoder, but thought I would ask before I took the shells off. I didn't know that the units could be run independently. I'll try these suggestions next.

The track voltage varies between 19v and 17v most of the time. The second time I tried to run the ABA at the track with the 'other' TIU and Z4000, the track voltage was right at 18v. This engine, as well as the others, have been running fine with my present setup. I strongly suspect a fault with the ABA leading or trailing unit.

G: My wife bought me this engine set from Jimmy Sutter in June 2010, she gave it to me for Christmas that year, but I was not able to run it until I had some track down, around May or June 2011. I am pretty sure that it is out of warranty. I will certainly take up up on your nice offer if I can't fix the problem myself.

Thank you guys for your real help, and I will report back as soon as I find something out.

Alex

You can't run both of the units independently, I suspect one of them has a slave board and will only run connected to the other A unit.  However, the lead A unit should run by itself.  From the description, I think it'll be speedy!

John,

Right you are!

I removed the shell from the leading A unit, and could not see anything out place, missing, or bad. See pictures.

I placed this leading A unit on the track, powered it to 18v, selected with the remote, started it up (sounds are fine), and when I moved the wheel to 1 SMPH, it took off just as before. Then I tried the trailing A unit by itself, and it did not do anything.

So it appears that the culprit is the leading A unit, as you guys suspected.

I'll be in touch with GGG.

THX!

Alex

PS. As you would imagine, I have several people visiting this weekend (TCA National Convention in St. Louis), and this Santa Fe passenger train is (was now) one of the trains I always ran when I have company.

Alex, I responded to your e-mail.  When you turn the rear truck by hand is there enough strain relief on the wire bundle that the tach wires are not stretching?

Unpowered and on the bench you can test continuity of the 3 wires on the tach to the same colors on the 7 pin connector (top of Power Supply Board).  G

Alex,

Just a thought.  That tach reader looks a bit far from the flywheel.  Just try putting a little pressure on it towards the flywheel and role up the thumbwheel.  The optimum spacing should be .030"

Dave

G,

Per my our emails and for the benefit of forum readers, everything appears to be fine; no strain on wires, no loose connectors, nothing out of place, etc. I tried what Dave recommended, but without success (next paragraph), so the locomotive needs to be repaired as we have already agreed.

Dave,

Good point. I measured it, and the gap was 0.042. I was able to push the reader so it would stay at 0.025. However, I tried it like this, and it still went full speed.

Thx!

Alex

My experience has been that the gap has to get pretty wide before you'll lose total control, usually it'll just starting running a bit ragged with partial reads.

I had that happen to 2 locos a few months ago, about an hour apart, when my grandchildren were running.  On advice of Barry B & others after my inside inspection, I reset both and they worked fine.  Never recurred and we were never able to figure out a cause.

Just like my computers and the like:  things happen with no rhyme or reason.

RJR,

Did you do a feature or a factory reset?

Thx!

Alex

As I recall, a feature reset.

A feature reset can't hurt.  If that fails, then a factory reset would be my next try.  Doesn't cost anything to try.

RJR, John -

I'll try that tomorrow.

I have several guys coming to visit (from the TCA Nat Conv) in a few minutes, later today as well, and I don't even want to do anything other than run the trains as I have planned. I substituted a UP F3 ABA passenger train for the Santa Fe, recorded a session that lasts 15 minutes and uses two trains, involves nine turnout changes, and am keeping my fingers (and toes) crossed. After that playback is over, I'll run several Legacy engines, manually.

I let you know the results when I do the reset.

Thanks!

Alex

If that doesn't work, check that flywheel at sensor isn't loose on shaft.

Ralph, I thought your issue was erratic and or sporadic behavior.  No harm trying, but when an engine is thumbed up to 1mph and it takes off immediately, that is a sure sign of no tach feedback.

Interesting enough the other often quoted idea is to reload the program.  Personnally, I have yet to run across an engine were a reprogramming has worked.  Never had an engine with just a corrupted soundfile.

Now, I have had one TIU that required a reload.  G

Alex,

I agree with G that it is a tach reader issue.  Reader/positioning, wires or U12 amp.

Dave

I would note for the record that on the two occasions when this happened to me, I checked the tach reader gap and the wire connections, and that made no difference.  The runaway continued until I did the reset.  In other words, one can't say with assurance that the problem is or is not the tach reader.  To this day I have no idea why it would have happened twic, on 2 different locos, and not recur after reset although months have passed.

Alex, did you have any luck with the reset, or did you wind up sending it to GGG?

Sounds like it's somehow getting into conventional mode and launching at the full 18v which would be "rocket launch speed".

Could this somehow be happening?

From the symptoms, I don't think it's dropping into conventional mode.  It starts up from the remote and sounds are triggered from the remote.  That wouldn't happen in conventional mode.  The fact that it takes off as soon as you apply any throttle seems to strongly suggest that it's not getting the tach pulses.  That's the exact symptom I've seen when a wire breaks off the tach sensor.

Alex may post more, but the engine had speed control off.  When I did a conventional reset it cleared.  There was a blown LED and lights were flickering some.  Replaced the LED and tested fine after the reset.

Alex said he did the feature reset via DCS.  So it is interesting that it did not clear.

One motor is running slower then the other (about 1V) uncoupled.  The engine would chatter as one motor was pushing the other when speed control is off.  With it on the engine runs smooth and quiet.  G