Divide and Conquer

Dear Nelson,

Firstly, if you unplug the decoder, plug in a jumper, and test it on analog DC,
does it still show signs of hesitation and hiccupping?
(speaks to "dividing and conquering" the issue).

I wasn't aware that the latest Athearn offerings used "outside bearing" systems with the sideframes part of the power path? Really _old_ athearn mechs (original black-cased 'semi-open' motors) did, but unless something has changed, from the "Blue Box" locos onwards the sideframes were plastic, and the bearings/pickup-points were moved inside the wheels?

I've a reasonable-sized roster of current-spec Ath SW1500s and an MP15AC, with no additional pickup tweaking or wheel-blackening cleaning they all run very sweetly and smoothly...

Happy Modelling,
Aim to Improve,
Prof Klyzlr

PS have you oiled the axle bearings or anywhere nearby?
Oil is _not_ always a good thing, the ath "sintered bearings" are oil-less and should not need attention,
and excess oil can attract dirt which becomes an "over time" insulator...
(matches your "got worse over time" symtoms, and would still affect the system despite the "tweaks" you've already tried...)

Bearings.

Prof Klyzlr the bearings are the inside frame type.  The metal tab that they ride in is the area of question.  Did oil them so maybe replacing them would help.  I don't have this issue with any other unit on my roster.  This being on of their "newer designs" I don't see any real improvements other than the fact they have eliminated the tin strip over the motor and replaced it with a plug in board instead.  As for DC operation, it doesn't seem as affected but I'm also limited to a 3 foot test track in DC.

Dear Nelson, Not sure

Dear Nelson,

Not sure "replacing" anything would be my first step. Do I read that you _did_ oil the bearing areas? If YES:
- pull the plastic sideframes off
- lift the under-truck keeper plate
- remove one axleset at a time
- seperate the axle halves, central gear, and the sintered bearings
- sit the bearings on kitchenpaper. and soak/mop-up any excess oil
(make sure to flip the bearing over, so you mop-up both sides ).

- use some kitchenpaper to wipe the axle sections clean of excess oil
- reassemble the axleset, and make sure to check that it's re-assembled in-gauge with your NMRA gauge
(never mess with wheel or axlesets without one!)

Repeat for all 4 axles

- retest on analog
(even 3' worth of crawl should prove correct operation of not)

- then reset the original decoder to factory settings

and retest on DCC using that decoder.

If no joy,
(analog appears OK, but DCC decoder operation = bad),

- try A/Bing a different decoder in the loco.

If the loco runs sweetly on analog, but hiccups and acts nasty on _one_ of the 2 test decoders,
(and not the other),
 
suspect the decoder.
(Maybe you're seeing a CV-mis-setting in one of the decoders,
or an actual mech-VS-decoder mismatch (the mech simply "likes" some decoders better than others?))

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Will try the cleaning thing!

I will disassemble the wheels and clean the bearings and try that.  Did look at the issue more closely and I believe that the "bearing to sideplate" connection is the problem area.  (shows high resistance from track to feed wire).

Will let you know how I make out.

What I have done

I have modified a few of those Athearn trucks to eliminate as much as possible any sliding electrical contacts.  I soldered fine wires to the bearings, and from there up to the motor (later, the decoder).  That completely eliminated the truck frames from the equation, leaving only the axle to bearing (and of course wheel to rail) contacts as the only ones not soldered.  I found that the trick was to solder the wired to the tops of the bearings, close to one edge, so that they would still fit properly in the frame slots and not interfere with the fit of the axles.

My next step!

Thanks Ken, that's my next step.  I have some .010 brass wire and plan on doing this just to eliminate everything possible.  Did this on some Atlas/Kato models that had the same issue at the bearing plate.  Eliminated the issue altogether.   What my thinking is, to solder fine wire to the side frame as a "wiper" to the back of the wheel.  Will tet you all know how I make out.

Prof_Klyzlr gave me the idea!

Ok   Prof_Klyzlr, you gave me the idea of divide and conquer!  Actually, diagnose the issue using process of elimination.  Boiled down to the NS "plated" wheels that are actually what looks like brass underneath.  Plating is all but worn off on 6 out of the 8 wheels and under magnifying glass all pitted bad.  As a marine technician by trade, when we find something pitted, the only repair is replacement! Athearn's "better" quality ready to roll line went with blackened wheels and blackened inside contact plates, and in my opinion did more harm than good.  Basically, I swapped out the "newer" style wheel sets for the good old fashioned sintered metal wheel sets that I polished, (see my article in the  August MRH tips section) and problem is 98% gone!  I wont say 100% because I know variables can happen.  I have never been a fan of plated wheels as I know over time it will wear off and what is underneath is usually impossible to clean reliably. 

I just had to think like a technician instead of a modeler.  

Pictures tell the story!

As you can see, the plating is all worn off and causing my power pickup issue.  I know the metal undeneath the plating will conduct power but there is such a small contact patch that any defect will cause it to lose contact with the rails. A high OHM reading led me to this conclusion.  Just got done doing some switching with the CF-7 and ran almost flawlessly through all my turnouts and crossovers.  

On to the next project.

In troubleshooting, a methodical patient approach always wins...

Dear Nelson,

Glad to hear you found the fault! I understand the logic you were using focussing on the keeper/contact-plates and sintered-bearings, but when it comes to troubleshooting, Willy Occum was onto something...
(or, said another way, "...Unless you're in Africa or a zoo, when you hear hooves, think horses - not zebras..." )

I agree that the old Blue-Box style truck<> frame and "bent steel spring contactor" system was maybe not the best solution, (although I've seen old BB Athearns still circulating on 4x8 analog-DC "trainsets" long after many other locos have died and gone in the trash), and replacing these paths with wire is a logical way forward. However, the newer (Horizon era) Athearn mechs with DCC-ready PCBs and truck<> PCB wire connections are larger devoid of the "classic" Blue Box issues. That both styles of Ath mech used the sintered bearings as both mechanical wear and electrical contact points doesn't seem to have made a lot of difference in performance either positively or negatively. (If it ain't broke...)

I'm not sure I'd be swearing-off all NS-plated wheels at this point, although _thinly_ plated wheels are indeed a pain... What I would want to ask is, how much wheel-sliding/juddering has this loco been doing to wear the NS plating away? What kind of trailing load does it usually have to handle? NS plating does indeed "wear under normal operations", but usually it takes ops of the magnitude of EnteTrainment or Minatur Wunderland to wear down to underlying brass in a "a few weeks" timeframe...

(Another thought, if this loco is usually run as a DCC consist with another loco,
maybe a revisit of the speed-matching of the locos in question might be helpful?)

If you're looking to re-equip the loco with decent NS wheelsets at any point in the future,
I'd reccomend checking out the plug-in replacements offered by NWSL...

http://www.nwsl.com/uploads/cat_chap3_for_web_9-20.pdf
(Start at Page 7)

Whatever the case, it's truly great to hear that you worked it thru and got it nailed down.
NB that your willingness to actually _investigate_ a failure, locate and confirm the _actual_ fault, and repair/resolve it hereby places you in a rare and shrinking category of "not scared of loco mechanisms" modeller,..

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Used!

I purchased it "slightly" used at a swap meet recently.  I will at some point replace the wheels with NWSL ones, but will try to post a few photos of my "polished" wheels I installed. Thanks for the info.

CF7 Problem

Hi, just like you I have had this engine for a while and I installed DCC/Sound in it along with custom lighting. I had this happen to me many moths ago and I fixed it ith older Bluebox wheelsets. The problem was fixed but, just recently it happened again and is running very poorly and stalling all the time. I've tried to file away the awful blackened metal contact plates the brass pickup squres ride on too. Any tips?

  The only Athearn locos I've

The only Athearn locos I've had trouble with were older blue box locos with the old wheels that get oxidized. Replacing the wheels with NWSL upgrades fixed my problems. If your wheels look clean and your track clean then you might check to make sure you don't have too much oil in the bearings as they need to conduct the current from the wheels to the sideframes.  Just as a test I'd try adding some graphite to the wheel treads and the track then see if it helps, maybe squirt some on the bearings too? If it doesn't help it wouldn't have taken too much time to try it :> )  ....DaveB

Thanks for the reply

Thank you for the reply. I've look at NWSL's website but was unable to locate replacement wheelsets. My track has never been cleaner and the wheels are as clean as can be. I'll try cleaning off extra oil as that may be part of it. When it stalls if I lightly push the truck from the side it starts to move again. This whole thing is very frustrating and makes no sense how it ran flawlessly for over a year and now started problems again. I'm thinking about doing a short video and posting it to Youtube then linking it here.

See this MRH thread on this subject.

https://forum.mrhmag.com/post/locomotive-tune-up-tips-how-to-video-12195936

And this video that shows you the end results.

I'm glad this came up again

This topic shows up with several different models and situations.  It is always on speed step one, the lowest speed.  Usually the step one speed has been lowered during programming.  I have a theory that stiction is playing a role here.  Yes, there has been a slight voltage drop due to some electrical imperfections.  This is the region where the system is extremely sensitive to any imperfections.  

I have been doing a lot of testing of various DC loco's.  I test all on rollers over the entire voltage range.  What I observe is a 0.3 to 0.5 voltage counts between where the motor will stop and where it will start again.  That is the result of stiction.  On the rollers this occurs around 4 volts on the power supply.  Take the rollers away and the start voltage drops to under 3 volts.  

Electrical imperfections act like the rollers.  With DCC the decoder allows you to run lower speeds, but when the integral of the pulse voltage goes below the motor start voltage, it will stop.  When it gets close to the average, it will start to visibly sputter.  This could only take a 0.1 voltage loss depending on where you set step one.  Unfortunately a humid day might cause that much voltage variance.  

Load and slope will further aggravate this sensitivity.  

I suspect that the slower you want step one to be the more frequent the maintenance requirements.  

I hope to have data that talks to this issue sometime soon.

Video

Here is my video of this issue. Very interesting study on low speed I'd love to hear more on this study down the road. However I believe my problem is solely the trucks as the sound system would still remain active even if the motor stalls. 

One other thing that might

One other thing that might help would be either conductalube (Atlas) or never stall on the pick ups. I do that with my locos and generally never have issues there. It could be that everything not just wheels will oxidize over time and needs cleaned and relubed.

Cleaning results

Just got done disassembling the wheels sets and cleaned each part of them and the trucks with rubbing alcohol. The container of alcohol was a light shade of yellow when they were all done being cleaned from all the oil I removed. Some things like lint and hair were also present in the alcohol. Pleased with how well the oil and debris were removed I then decided to clean the trucks with a small amount of rubbing alcohol too. After resembling the wheel sets and trucks I was edger to see how much better it should run. Fired it up and the same problem nothing changed   Slow speed is also not one of the factors as originally thought by me and others as I just found out at almost any speed this happens just like as show in my video previously posted. I know some of you have suggested conductive oil but I'm not to sure how much of a difference it would make as these wheel sets and bearings are completely spotless. I'm ready to give NWSL replacements a try here soon. Any more tips guy? I've spent a lot of time and money on this locomotive I'd just really like to see it run like a good old KATO. Love the tips and reply I've been getting so far very helpful so thanks guys.

Before replacing the wheels

Follow the Prof's original suggestion.  Run on analog DC with the decoder out of the circuit.  If the problem goes away the decoder is probably the problem.  

If it continues at all power levels, I'm not convinced the wheels are at fault.  Particularly since they have just been cleaned.  

If you can rule out the decoder,  Then you need to try it isolate it further.  I would disconnect the drive from the motor.  Then run the motor by itself.  If it runs erratically, then there is your problem.

(if you can measure the current while checking these steps out it will be helpful.  If the voltage is dropping because of lost connection, the current will be going down as well.  If the problem is some kind of binding, then the current will be going up.)

If the motor runs fine then reattach one spline and truck and run again.  If everything runs fine, then repeat with the other spline and truck.  Before making these last runs, I would verify that you can rotate the spline freely with no binding.  

Let us know what you find,

On second though

It may be the wheels, but not because of electrical pick up.  I have recently been doing some testing in this area, and I have found a common problem with loose wheels on powered axles.

In the case of the Athearn BB engines, this is the half wheel shaft is loose in the axle gear.  Hear to fore, I would have said that these axle gears were cracked.  Now I’m not so sure.

Recently I have been working with four Athearn BB engines.  They range from new, never out f the box, to well used.  Of the thirty two half wheels, twenty two were loose.  That includes 3 sets out of the 4 on the new engine.  I found this condition after running tests on all four.  Because of this I have repeated the tests with sets of tight stock wheels.

What I see is that the loose wheels cause the engine to run slower at a higher current level.   I intend to discuss the details in another post.   The decoder uses current draw to determine how to control the engine speed.  It does not know that the motor is running on a different speed-current characteristic.  This may be the source of your running issue.

This is likely a progressive fault.  I suspect all axle-wheel joints will loosen over time because of the stress levels unless something is used to keep them tight.

Let us know if you can easily turn any of your wheels in the axle gears.  They should be difficult to turn.

Well, The Findings

Hi all lots of great advice here. Since I last left off I decided to try a little bit of everything. Here is what I did in order

1: Removed shell and found broken wire going to rear left truck (hard to tell it was broken) see below photo

2. After re-soldering this broken wire I was for sure certain this was the problem all along.

3. Tested the unit, still having same problem as before

4. Polished wheel sets until all the chemically blackened crap was gone and a nice shine was present (like photos you posted before)

5. With new wheel sets installed attempted to run locomotive, no luck same problem

6. Uninstalled DCC/Sound decoder

7. Decoder was not the issue unit ran poor on DC but never died hum......

While watching operation on DC only I noticed to motor would stall (hence DCC decoder shutting down like a user commented previously) so, the motor would randomly stall at varying speeds (fast or slow) it would never fully stop running however, it would just turn really slow then back to normal or motor would hum if it did stop. Sometimes the stall was very minimal but I assume on DCC the decoder would be very sensitive to any sort of motor stall. So, with electrical connection issues now off the table it's come down to poor motor operation. This motor never used to run like this it ran great, never ran this engine too much. I guess like many Athearns I have owned their motors just can't match the quality found in other manufactures locomotives I hate to say. So where can I go from here? Would a KATO motor fit or would major mods be required? Is there any way to fix a Athearn motor like this? This whole thing has really gotten me bummed after all the hours I spent with adding custom lighting and details/decals to this CF7. Any help would be great. Thanks guys!

Can you rotate the fly wheels easily

Usually the motor doesn't just die.  Your description sounds like one of the trucks has binding gears.  It is a common problem with the gear on the top of the truck tower.  This gear is held in place with two square brass bearings.  One of these will seize on the shaft.  Dragging on the motor.  It can cause it to stall.  

If you rotate the fly wheels you will feel this drag, if it is there.  They should be easy to rotate.  If not, you have to isolate which is causing it.