Erratic operation of a ready to run MRC in Roundhouse Engine

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gfmucci

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Dec 25, 2006
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Unusual sensitivity to voltage drops: Roundhouse-MRC Engine

I bought a Roundhouse 4-4-0 engine ready to run with an MRC sound controller a few weeks ago. I use it at the club I just joined.

It runs great on 95% of the club track. However, there are two sections where it either barely moves, even on full throttle (no incline), and makes a clicking sound from the speakers, and another spot where it moves in jerky movements, where the engine seems to cut out for a half second at 2 second intervals. In both of these situations, the headlight remains on full and does not blink at all. No one else's engines have problems in these areas. The track voltage throughout the system is between 12.5 and 13.1 volts. The wheels are clean. The track is clean.

Except for these two areas, which are each about 10-12 feet long, the engine runs smooth and predictably.

At first I thought it was a voltage drop problem. But the voltage is actually about .2 or .3 volts higher in these trouble areas. Could it be some form of RF interference in these areas? How would I trouble shoot this problem? Or is it clearly a defective controller in the engine?

Like I said, no one else's engines (and there are dozens) have problems on this layout, especially at these locations.

Any ideas:( ?
 
Yes, the other loco's show no problem at all in these areas. Another guy who is familiar with these engines said they are particularly sensitive to dirt pickup...that the "stuttering" sound from the speaker is from lack of voltage...that the combination of dirt on the pickup areas of this loco and dirt on those specific sections of track would be a rational reason why it only affects this loco at these track sections. I'll try cleaning these areas first before I swap electronics - which I don't know how to do anyway. I have a call into Roundhouse. My next to last resort would be to reset the controller.
 
A Roundhouse rep called me back today. He was 90% certain it was dirt - somwhere - tracks - wheels - or a combination. I will do my due diligence cleaning when I return to the Club Saturday and advise. :| Thanks.
 
This may also be caused by a defective pickup on one set of wheels.
May run OK on some of the track but have problems where dirty track
or poor track feed leaves a dead spot that the good pickup stalls on.
If all pickups were OK, it would go right over that spot. Are the other
locos which pass it OK 4-4-0's or longer wheelbase??
 
It is true that mostly longer engines run through these areas. I'll see if I can test another shorter one through those sections. However, it is not just an isolated spot or two. I can hand hold my engine and drag it across 8 feet of track and it maintains the same anemic, sputtering behavior, even at full thottle....then as soon as it reaches a certain point, it has full power again. That "certain point" is always at the same place. I thought initially it was a voltage drop in a block, but the voltage checks out fine at 13.1. While I'm advised its a combination of dirty wheels/pickup/track, if cleaning doesn't cure it, my next guess would be some form of RF interference. I hope I don't have to go there. I'll know by Saturday, the next time I'm at the club.
 
If it runs fine everywhere else but certain sections, it is the track. If it was the locomotive it would act the same everywhere. It might not be getting a correct DCC signal through the rails. I had that problem with mine on a temporary segement until I ran feeder wires to that section. I have had no pickup problems on either of mine and I don't clean my track at all.

Harold
 
gfmucci said:
It is true that mostly longer engines run through these areas. I'll see if I can test another shorter one through those sections. However, it is not just an isolated spot or two. I can hand hold my engine and drag it across 8 feet of track and it maintains the same anemic, sputtering behavior, even at full thottle....then as soon as it reaches a certain point, it has full power again. That "certain point" is always at the same place. I thought initially it was a voltage drop in a block, but the voltage checks out fine at 13.1. While I'm advised its a combination of dirty wheels/pickup/track, if cleaning doesn't cure it, my next guess would be some form of RF interference. I hope I don't have to go there. I'll know by Saturday, the next time I'm at the club.
Click to expand...

Unfortunately, a voltmeter doesn't tell you what is going on under load. Most voltmeters have a very high input resistance so they don't load the circuit. You need to measure the voltage at the decoder when it's stalled - I'll bet it's not 13 volts then. A current meter while stalled will tell you whether it's stalling due to an open or a short circuit (the below assumes open, but an intermittent low resistance is a less likely possbility).

As Harold said, if it the situation always changes at a "certain point", then there is a problem with the track. The rail joiners at that "certain point" are conducting poorly or intermittently. If there are feeders in that section, then one of the feeder wire joints is bad, also. Could be certain weight combinations or wheels cause the joiner(s) to shift ever so slightly and lose contact. As Harold said, run another set of feeder wires to that section of track, and at least one problem will be solved.

You may still have dirty wheels and/or pickup problems on the locomotive, too.

If you can switch the section of track to DC instead of DCC, troubleshooting might be easier. Doing this takes DCC signal corruption and decoder setup out of play, and rules them in or out as possible culprits.

The MRC decoders used in Athearn/Roundhouse DCC locomotives are apparently more susceptible to losing their "brains" than most other decoders. A poor signal or intermmittent contact can cause problems with MRC decoders that other decoders will handle fine.

just my thoughts
 
It's interesting that amidst the various problems I described for this engine, when on the "good" sections of the layout, it never lost its "brains", never had to be reset, it just starts chugging along as if nothing ever happened.
 
OK. Here are the results of additional testing of the Roundhouse 4-4-0 MRC sound controller engine on my club layout...

Wheels were cleaned. Track is clean.

When any other engine is on the same block at the same time as my Roundhouse, voltage or amperage (not sure which) drops below a certain threshold of tolerance of the MRC electronics. No other engine is affected in any visible or audible manner. Only my 4-4-0. This circumstance caused a drop in power available to the 4-4-0 which resulted, as before, in clicking sounds from the speaker, and sputtering, jerky, slow operation of the engine. The question I will pose to Roundhouse Monday is this: Is this behavior within the performance spec of the engine, and nothing will be done about it; or, is this behavior something beyond the design spec., and either an adjustment of some kind or board replacement will be provided?

What are your thoughts?
 
gfmucci said:
Is this behavior within the performance spec of the engine, and nothing will be done about it; or, is this behavior something beyond the design spec., and either an adjustment of some kind or board replacement will be provided?
Click to expand...

I certainly hope that the kind of problems you're having aren't within the performance spec. I was just about to buy the same unit when I saw your thread and am anxiously awaiting the resolution, especially whatever Roundhouse has to say. Where did you get yours, if you don't mind my asking.
Doc
 
I got it a a LHS in Pensacola, FL...Trains by Johnson. I didn't bother going through them for this troubleshooting exercise...they are 50 miles away. Roundhouse was very responsive by phone. They called me back within a few hours of my call. They asked me to double check the cleaning first. They gave me the clear impression that they intend to make it right. I'll find out tomorrow.

I do have to say, that this is a sweet running little engine - runs very smooth; the momentum is adjustable, both start up and stopping. It works flawlessly, except for when the juice is drawn down by other engines. Experienced club guys estimated it runs as slow as 5 scale mph. And it has a good top speed at close to 60 scale mph. I had it pulling 5, 70' passenger cars without a problem - probably beyond its proto load limit.
 
jeffrey-wimberl said:
Run feeders to those areas where it's having trouble. Worked for me when I changed to DCC.
Click to expand...

I totally agree with Jeff. If the decoder is having signal problems when another locomotive is in the same track section, you need additional and/or beefier feeders in that section of track.

If it weren't for the fact this only happens in a particular area, I would suggest checking to see if the DCC power was adequate. Since it is limited to one area that has an inadequate signal when both the MDC and another loco are present, it has got to be the electrical feed and/or rail joiners.

The sound decoder is going to draw more power than non-sound units. Typically sound decoders draw about 0.6 amps, and a non-sound loco will draw 0.3 amps or less.

just my thoughts
 
Here is the "definitive" answer from Dave of Roundhouse (they are excellent with return calls!):

This engine is apparently more sensitive to voltage drops than others on the the club layout (only explanation as to why this engine is the only one experiencing problems on these sections of track). The engine is not out of spec as far as the voltage operating range is concerned (I don't know how he would know, since this particular engine's tolerances haven't been measured by anyone.) He agrees with a couple of previous posters who said additional power needs to be routed to the sections of track where the voltage drops and problems for this engine are occurring.

I told him I am the "newbie" in the club...coming in with this little engine experiencing problems with their layout that no one in the club has experienced in umpteen years, and telling them that my engine requires an upgrade to the juice on a couple of track sections. Wish me luck!
 
Good luck with the club. I think the Roundhouse rep is giving you the straight scoop, but I also know that if only one locomotive has a problem with a section of track, the presumption is that that one locomotive must have a problem because no "one but you has any problem." Is anyone else running a sound equipped locomotive? You may have to wait until Athearn or Roundhouse comes out with a new sound equipped locomotive that others want to run and then when enough of you start having the same problem at the same place they will have to admit that they have a track problem.
 
This MRC compatible problem has occurred more than once recently on our club layout. I've spoken to those involved and will attempt to post some of their opinions/observations.

My own feeling, as a non-technical user type, is that I'm waiting to see if MRC will come back and explain why their modules have trouble working side-by-side with other vendor's products in this evolving DCC market before I commit to using/buying a product containing a MRC module..
 
After the phone conversation I had with Dave of Roundhouse, I e-mailed the link to this entire thread to him... I hope he/they see how these problems can create unhappy customers.

I discussed this thread with our club president. We will conduct another test next week to see if this same problem can be created in other blocks of the layout that have two or more engines running simultaneously in them. This will tell us if it was just a block wiring problem (just the blocks where we initially observed the problem), or if the problem is universal over the entire layout.

If the problem for this engine is limited to just a block or two, a block wiring upgrade may be the solution. If the problem occurs over the entire layout, the engine/MRC is most certainly the lone culprit.

In either event, this engine has proven itself to be more sensitive to voltage variation than any of the several dozen engines (with and without sound) operated by club members on this layout.:-(
 
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