Erratic operation of a ready to run MRC in Roundhouse Engine

Discussion in 'HO Scale Model Trains' started by gfmucci, May 2, 2007.

  1. gfmucci

    gfmucci Member

    OK, here are the facts of this problem so far:
    1. Running a Roundouse 4-4-0 "American" with factory installed MRC controller and sound
    2. On a club layout using the Digitrax remote system
    3. Wheels clean and track clean
    4. Engine slows to a jerky crawl on one block of track, especially with other engines on it
    5. The headlight remains constant on - no flickering; no, there is no capacitor that enables it to stay on when it does not make good contact with the track because when there is no contact, the light goes out immediately - engine is in full, good contact with the track.
    6. Of the dozens of engines that operate on this layout, this is the only one that has difficulty on this layout. I guess someones engine has to be the most sensitive.
    7. Conclusion so far...this engine is the most sensitive to voltage drops of all the dozens of engines that run on this club layout
    8. It exhibits the same slowly, jerky, clicking behavior when the club layout is switched to "N" (12 volt) mode compared to the "HO" (14 volt) mode. The club "pros" say it should run OK (if not a little slower) in the N mode.
    9. They advised me to run it on the train dealer's layout (Trains by Johnson in Pensacola, Florida where I purchased it) to determine if it shows the same problem in N mode on their layout.
    10. The dealer may have more influence than I do if he agrees the engine does not perform as it should.
    11. Roundhouse has claimed the engine and controller are "to spec" without seeing it or measuring it.
    12. If it is operating "to spec", beware of using this engine on club layouts with other engines operating because it will experience the same problems. If this engine is NOT to spec, I hope a trade will remedy the problem.
    Does this diagnostic, especially 8 and 9, make sense to you?

  2. jeffrey-wimberl

    jeffrey-wimberl Active Member

    It sounds to me as if something is not right with that locos decoder.
  3. alastairq

    alastairq Member

    two-pennor'th here, from someone who doesn't 'do' DCC or sound....backward UK for you........if the club layout is 'sceniced', ie track ballasted and painted, it may be possible the rail head isn't QUITE as 'clean' as one would wish for.
    Plus, those 'problem' sections may well not be quite as level as they would want to be.....noticeable especially with a 4-4-0, of limited pickup length? (I take it the loco chassis isn't 'sprung' or compensated in any way?)

    However, since US-designed prototypes are historically capable over rough track, I would take a GOOD hard look at the actual railheads in these areas. If painted track is present (especially if a spray painting technique was used) then there could be a problem with minute overspray. Despite copious cleaning sessions, very often minute sprayover can be missed.....especially if the evidence of 'clean track' is the uniterrupted passage of a long modern diesel loco?
    Also, many paints can leave a sort of 'residue'....after cleaning off.
    This may not be 'visible', but might make its presence felt later?
    If the railhead itself has undergone an 'abrasive' cleanup, then the head surface might contain minute scratches....if these are filled with residue, then a loco with a limited pickup system might suffer where others ignore?

    Are these 'bad' track sections 'easy' to reach?

    I'd be 'inclined' (I'm not level-headed by any means) to make up a couple of long wire 'jumper' leads...crocodile clips on all 4 ends.....then roundly 'bar' any other engine from those sections on club night, whilst you try your loco, with the track sections linked via your jumpers to a known, GOOD section..........if all is well, it's the track.
    (possibly a dry 'soldered' joint?...or a dodgy fishplate ...sorry, rail joiner to you lot!)

    Either way, if I were head serang of a railroad club, full of pride 'n joy, I'd be bending over backwards to help out a troubled member, regardless of how 'new'.....

    just a thought....???
  4. hminky

    hminky Member

    It will not run on the "n" mode on Digitrax. It will display that charactricstic of choppy action. It needs at least the 14 volts. A power loss due to bad wiring will also cause the condition.

    I have one 4-4-0 that will run on the "n" setting and one that won't.

    That is why I don't believe the "pros" at clubs. There is genius everywhere but never enough intelligence.

  5. 0-4-0 Steamer

    0-4-0 Steamer New Member

    Have you cleaned the inside surface of the rail? I use a silver quarter and it kind of burnishes and cleans the inside too. Also, my 4-4-0 has trouble in places where my other locos don't and it's an older one by a different maker. I figure that when I can find the right size wheels for my tender I will put pickups on it too. I understand that will help keep constant current. Does your tender have pickups installed? That may be the trick here if it doesn't. I have finally got it running pretty well just doing the quarter trick.
  6. gfmucci

    gfmucci Member

    Yes, the tender has pickups, as well as the engine.

    As for cleaning the inside of the rails, I will find a different hobby before I begin doing that. When mine is the only engine out of DOZENS in the Club experiencing a particular problem, I am not about to begin cleaning the inside of the rails of the Club layout.

    My problem is a combination of:

    The Club believes the problem is with my engine, thus their refusal to increase the amperage on a section of track where the problem is occurring. After all, my engine is the only one out of dozens in the Club experiencing this problem. (However, this act of charity would very likely solve my problem.)


    The manufacturer of the engine does not acknowledge there is anything wrong with the engine (Roundhouse/Athern). They say it must be the layout. wall1

    I have not contacted MRC yet, but I guess I should.

    The hobby shop where I purchased it (Trains by Johnson in Pensacola, FL) offered to evaluate it when I bring it in on Saturday (50 miles).
  7. hminky

    hminky Member

    It is the layout.

  8. 0-4-0 Steamer

    0-4-0 Steamer New Member

    I guess I wasn't real clear on how you do this. It isn't a big deal to do. Just take the quarter at an angle and rub it back and forth between the rails. The quarter is a perfect size for this and it will remove any scenic spray of paint from the inside of the rails at the spot in question. It should take about two minutes to do and it really works. It will also smooth any scratches that may be there. No need to change hobby's when a loose piece of change may fix the problem in no time at all.
  9. gfmucci

    gfmucci Member

    Sure, it is not a big deal to do that track cleaning exercise. But as I noted in a previous post, dirty track or dirty wheels have been confirmed to not be the cause of the problem. Dirty track, dirty wheels or lack of circuit continuity at switches has the very visible result of making the headlight flicker or go out altogether. In the instance when the erratic, crawling, jerky movements with clicking sounds occur, the headlight stays on fully bright, with no flicker whatsoever. There are other issues involved.:|
  10. 0-4-0 Steamer

    0-4-0 Steamer New Member

    hmmmm, quiet the quandary! Good luck with it. Maybe a replacement loco is in order.
  11. hminky

    hminky Member

    It is not the amperage. You are experiencing a voltage drop in the section of track.
    I can duplicate that condition on my staging oval. If I disconnect the oval and only use jumper wires, duplicating a bad connection, the Roundhouse 4-4-0 will perform like you discribe.
    If my Digitrax command station is set to n, a lower voltage, it will do the same thing.

  12. gfmucci

    gfmucci Member

    Exactly. The other engines on the block draw amperage, lowing the voltage to the point where this engine works quirky, but all the other engines work fine. The question remains, why is this engine the only one doing this?
  13. gfmucci

    gfmucci Member

    "N" is typically ~12 volts. HO ~14 volts, right? your Roundhouse more sensitive to voltage drops than your other engines? Is there anything you can do besides preventing/avoiding voltage drops? How much variation in voltage is acceptable by the average engine/controller?
  14. pgandw

    pgandw Active Member

    Because, as you point out, the MRC decoder (especially this particular one) is more sensitive to voltage drops than the other engines. This doesn't mean it is out of tolerance - it just means it is the most sensitive of the locos at the club.

    You have 2 things happening here.

    1) You have excessive voltage drops at the club layout that will eventually cause problems with more than just your one engine. There is no NMRA spec for allowable DCC voltage drop. All the DCC recommendations I have seen about the issue say that the wiring should be robust enough to keep voltage drops under maximum load to 5% or less (typically max voltage drop of 0.7 volts). Conventional DC can usually tolerate much greater voltage drops.

    2) your MRC decoder and engine are more sensitive than most to voltage drops. So your 4-4-0 will be the best detector of club DCC wiring problems, just as some larger steam engines are the best detectors of track problems. In Harold's case, one of his 4-4-0s has problems with a less than 2 volt voltage drop, the other doesn't.

    You can fix either or both issues. Fixing the wiring - more feeders and heavier gauge wire if necessary - fixes the issue for the future for all locos. My suggestion would be that you offer to install the extra feeders in the troublesome section of track yourself to prove the point, and fix the problem for all.

    Replacing the decoder with one less sensitive to voltage drops will fix your loco. But the problem will reoccur when somebody else buys an Athearn/Roundhouse steam engine that happens to have an MRC decoder at the more sensitive end of the manufacturing tolerance band.

    my thoughts, your choices
  15. gfmucci

    gfmucci Member


    You about wrapped it up. That makes a lot of sense. I appreciate your comments. I'll talk with the club guys again and see what involved in this layout power upgrade.
  16. gfmucci

    gfmucci Member

    The end of this saga...

    Since I am new to the club, and not experienced with someone else's complex electrical power arrangement, my jumping in and upgrading the power grid was not a viable option. And the upgrade components would likely cost well over $100.

    I visited my "local" hobby shop (50 miles away) yesterday where I bought my Roundhouse engine. They conducted the supreme test: They tried to run the engine on 12 volts (the "N" voltage). It replicated the same problem as on the club layout: slow, jerky movements with a clicking sound - the sign of the controller reacting to low voltage. You might ask, "HO isn't designed for N scale voltage (roughly 2 volts less than HO), why would that be a good test?" Because every HO engine at the club and, fortunately, every HO engine this dealer had experienced was capable of running on N voltage. He then tried another Roundhouse product with sound on N voltage. It exhibited the same symptoms as mine.

    Bottom line: He gave me full credit for my Roundhouse in exchange for an upgrade to a Bachmann Spectrum USRA Heavy Mountain 4-8-2 with Tsunami sound. This exchange cost me $70. Yes, this engine runs fine on N voltage - probably an essential if you plan on running on untested or underpowered club track.

    The Roundhouse 4-4-0 with MRC sound was a sweet little engine, and I hated to see it go. It would be great with a properly tuned club layout (which my clubs' layout is obviously not) or as a part of private layout where the user has control over the power he supplies to the track. With the remote controller that comes with it, it would make a great engine for a single engine layout. But it is definitely more sensitive to voltage variation than my club honchos wanted to fool with.
  17. jeffrey-wimberl

    jeffrey-wimberl Active Member

    All this means is that when another club member has a similar problem, the honchos will blame the loco and/or loco owner instead of the flaky track. The only thing that changed is you got a much better loco in exchange.
  18. gfmucci

    gfmucci Member

    All 'tis very true. But perhaps after the 2nd or 3rd similar issue, they will finally upgrade their substandard block. Might take a year or two, though.

    Another way to look at it, from the Club perspective, is that no standard was violated by their layout. No standard exists as the basis for declaring the Club track out of compliance. All the engines that operated on the layout worked fine, except when mine came along. Sooner or later, there will be a standard established. Until then, the "N" test is as good as any for an HO engine.

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