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swchief3
Passenger
USA
142 Posts |
 Posted - 12/20/2013 : 08:15:26
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After three and a half months in service, the first of my three Kato P42s, AMTK 68, had an on-the-road failure. The front truck, which had been problematic from the beginning, failed earlier this week. I was running the unit in trail position, when the front truck froze up and shut down. When this happened, I isolated the unit and tested it. The front truck had developed considerable binding and resistance, and the current draw nearly doubled. Needless to say, I pulled the unit out of service immediately. 
Tonight, after switching back to Athearn for a bit, I opened up AMTK 68. I did a partial disassemble on the lead truck, and cleaned the wheel wipers. They were dirty, but cleaning them did not solve the problem. (BTW, the original problem was the truck stalling on a specific junction point, and it's a place where nothing else stalls.) Cleaning the wheels did not solve the problem. Took the motor and drive assembly out, to check the truck gears for binding. Found none. Tinkered with the PC board. No change. Took the left-side weight out, and reversed the contact bar, thinking maybe there was a contact issue. No change. After doing all these things, the stall problem actually got worse.
Next thing I tried was swapping trucks with another unit. I took AMTK 161's lead truck, and swapped it with AMTK 68's, and the 68 did indeed run better. When I put the "bad" truck on the 161, that engine did quirk a bit on that magic spot, but it didn't quirk to the point of the 68. Kinda strange. So, I will order a replacement front truck for the 68, and we'll see what happens. I hope I don't run into a situation where, if you replace one truck/motor, you have to replace both. I'm not anticipating that, given the mechanics of the coreless motor, but I've been wrong before...
I was bummed by the failure, because I had gotten to a good place with these Kato P42s, and was about to start selling off some of my Athearn P42s to facilitate acquiring the Heritage units. Then, AMTK 68 failed. I then got a few Athearns out, and gave them yet another dose of TLC before putting a couple on the road. After an hour of good running, they have started falling apart again, e.g., motors binding up and getting close to graunching again, and a unit I did not put on the road throwing a driveshaft when I tested it. Same problems, over and over and over again. My hand is being forced to switch to Kato.
I sure hope this new front truck will do the trick. Note that all these problems worsened after the short warranty period expired. It was the first engine of the series that I got, so I didn't know that what I was dealing with was potentially a bad truck; I thought it was just the nature of the beast. So, we'll see.
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Edited by - swchief3 on 01/31/2014 23:17:00 |
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swchief3
Passenger
USA
142 Posts |
Posted - 12/21/2013 : 05:09:35
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Tonight (Friday, December 20th), I tried working on AMTK 68 again. Unfortunately, things got even worse than they were last night. I did a complete tear-down on both trucks, checking the wheels, cleaning the wheels by hand, adjusting the gauge, checking the gears, and adjusting the wheel wipers. Result? The engine ran WORSE! Much worse. The thing started stalling all over everywhere, and both motors took turns stalling completely. Eventually, the thing started to run a little better, and pulled the nine-car train by itself. When I isolated it again, it started to sputter and die. I couldn't find any problems with the gears or with the electrical pickup components, yet the thing sputtered and jerked all over the layout.
Removed the PC board, and cleaned the contact points, seeing that there was a bit of smudge. Result? The engine ran even WORSE! And, the light settings changed on their own. That's the second time that's happened with this engine. And, during testing, the lights blinked on and off a lot.
This is what I'd call an epic failure.
I don't think these failures have anything to do with my having applied lube. I did NOT lube the motor. I lubed the worm shafts and the flywheel shaft, which are on the opposite end of the truck. In order for the lube to get to the motor, it would have to pass horizontally through one to two chambers, plus get past the female receiver, to get to the motor. If the lube were to travel anywhere, I would think it would travel DOWN into the gears, rather than across.
My sense of things is that replacing the trucks would not make a difference. There are some serious electrical gremlins in this thing, and I can't find them.  This engine has turned into a nightmare on wheels.
UPDATE: I didn't stop to think that, maybe, the PC board is bad. But, a bad PC board wouldn't explain the results I got when I swapped trucks. I guess I'm going to have to bite the bullet and send the thing in to Kato. Didn't want to do that, but I don't have a choice now. |
Edited by - swchief3 on 12/21/2013 05:16:47 |
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swchief3
Passenger
USA
142 Posts |
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swchief3
Passenger
USA
142 Posts |
Posted - 12/24/2013 : 04:27:06
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| Ordered a new PC board for AMTK 68. Should be in by the end of the week. We'll see if that fixes the problem. Now, AMTK 161 is showing similar characteristics to AMTK 68, before it failed. I'm worried. |
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sschaer
Moderator
913 Posts |
Posted - 12/25/2013 : 08:49:56
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| strange that a broken board causes such behaviour. but then, h0-scale might be completely different from n-scale regarding pc boards. |
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swchief3
Passenger
USA
142 Posts |
Posted - 12/25/2013 : 19:04:14
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quote:
Originally posted by sschaer
strange that a broken board causes such behaviour. but then, h0-scale might be completely different from n-scale regarding pc boards.
Hi, Sandro! Merry Christmas! 
I'm not 100% sure it's the board, but that's the best explanation (?) I can come up with at the moment. I don't even know how a board can really "fail", unless it's bad from the start. Do N-scale boards cause this kind of wacky behavior when they fail?
I've been reading a bit about the presence of capacitors on PC boards, but I don't know if these Kato boards have them. These engines max out at 12v, as opposed to 16v, and I wonder if it's the presence of a capacitor that gives a board 16v capability. Even so, my power pack feeds in the right voltage for whatever I'm running. I was a little bit worried that maybe I'd blown the board, but I've never exceeded the 12v limit.
I did another wet-clean (alcohol on cloth) on AMTK 68's wheels late last night. The wheels were a little dirty, but not excessively dirty. There was a dull film, though, that came off. Don't know what that is. The engine ran better overall after the cleaning, and the lights no longer blink or flicker, but the engine still lurches and jerks going forward. It doesn't do it in reverse, and it does not seem to misbehave when it pulls the train alone. But, run it forward solo, and it still stutters and lurches. And, both trucks still take turns stalling completely.
I think I will call Kato tomorrow, assuming they're open the rest of the week, and see what they say. On their website, they encourage us to try fixing our problem engines at home first, so that's what I've done. But, I'm running out of ideas! |
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swchief3
Passenger
USA
142 Posts |
Posted - 12/27/2013 : 23:05:24
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New PC board came in today (Friday, December 27th). Sadly, it did NOT fix the problem. I didn't get a chance to call Kato to talk to them about this engine's erratic behavior. I'll just send the thing in. I don't know what else to do.  |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/04/2014 : 05:05:09
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Good news! After getting the trouble-prone AMTK 68 back out of its box, and messing around with it some more, I stumbled into what I think has fixed the problem of the erratic running.
Since replacing the PC board didn't work, I took the engine apart again, looking for clues of poor electrical pickup. After lots of head scratching, I started playing around with the wheel wipers. What became evident, after lots of trial and error, was that those wheel wipers have to be angled a certain way. These wheel wipers have a hole in their lower center area, at the base of the vertical "fin". That hole has to fit over a small spindle on the truck's gearbox sideframe. It seems that, if the hole and vertical fin aren't making enough contact at the spindle point, then the electrical current is interrupted. (I don't have my camera handy, nor do I have a truck disassembled. I'll try to post a photo or two of the wheel wiper and truck assembly later.) So, I bent the "arms" out a bit, i.e., away from the gear tower, making sure the wheels' axles still made contact with the wiper, when moving laterally. Bending these "arms" out forces that center point inward. This adjustment, plus the pressure the plastic truck sideframe applies to the wheel wiper, seems to be doing the trick, in terms of keeping that wiper in contact with the spindle.
After messing around with AMTK 68's wheel wipers, I test-ran the engine. After awhile, it started running more normally. The lurching, stuttering, surging, and lagging went away. This engine still has an issue with the rear truck locking up when I open up the throttle, but once it kicks into gear, the engine runs fine. And, that one magic place on my layout, where AMTK 68's lead truck always seemed to stutter and/or fail, is no longer an issue. The engine no longer stalls there.
I applied the same "fix" to AMTK 161, which was starting to run extremely erratically. Its wheel wipers needed the same adjustment. The engine is running like a charm now, and it's the best it's ever been! I'm running it now, with AMTK 188 trailing it, and the engines are smooth as silk. These engines are really nice now. They don't surge or lag any more, and their running characteristics are MUCH better. Acceleration and deceleration are 1000% better now, and much more realistic than before.
I'm going to run the 161 and 188 for the next few days, to see if the good running continues and the "fix" holds. I hope to get the 68 on the road, too, to see if I can get that freeze-up worked out. At any rate, I wanted to let you all know that these engines are doing much better. That wheel wiper set-up seems to be this design's Achilles' Heel.
We'll see how it goes...
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swchief3
Passenger
USA
142 Posts |
Posted - 01/05/2014 : 04:37:16
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Well, the "fix" didn't last. Running was good this afternoon. Running this evening was right back to the way it was. AMTK 161's rear truck is starting to fail, and the unit is running erratically and losing power again. AMTK 188 is surging, and otherwise running abruptly. The worst of the three units, by far, is AMTK 68, whose rear truck has just about failed completely.
This is ridiculous. The 68 is only entering its fourth month of service, and it's all but failed. AMTK 161, which I got a couple weeks after the 68, is beginning to fail. So, if the pattern holds, the 188 will fail in about a month or so. These failures come after powering a nine-car train, running paired, and running the full range of speeds.
These engines should not be failing like this, especially not for the price. Some of my Athearn RTR P42s and P40s are ten years old, and are still running. Note that I didn't say running "well", but they are still running. For both the price and the hype, these Katos should be better than this.
As a sidebar, I tried this wheel-wiper fix on my Kato F40s, and the results were amazing! All three units match now, and they run a lot more consistently than before. However, given the epic failures I've had with the Kato P42s, I'm worried that the brief success I've had with the F40s may not last. I'll be running them next, to see how they hold up. They may be OK, since we're dealing with a single motor, vs. two coreless motors. We'll see.
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Edited by - swchief3 on 01/05/2014 04:39:17 |
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sschaer
Moderator
913 Posts |
Posted - 01/05/2014 : 14:49:53
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this sounds strange.
guess we need to take a more sophisticated way of troubleshooting. i think there are some issues which are summing up.
just thinking out loud :
- if the power supply does not deliver enough ooomph an engine might stutter
- if the electrical path from track to motor is not good enough to provide enough amps an engine might stutter
- never ever use abrasive tools to clean contact strips. use a tooth paste, automotive polishing paster or similar.
- n-scale engines have 5-pole motors. if one pole fails it runs erratically
- trucks locking up/binding might massively increase the needed amps causing issues (see 1 and 2)
just noticed you mention coreless motors. there are several throttle packs which are not safe for coreless motors. any kind of pulsating power might cause issues. best would be to try the engines on pure dc (maybe even a 12v battery). |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/05/2014 : 21:40:38
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quote:
Originally posted by sschaer
this sounds strange.
(snip)
just noticed you mention coreless motors. there are several throttle packs which are not safe for coreless motors. any kind of pulsating power might cause issues. best would be to try the engines on pure dc (maybe even a 12v battery).
My power pack is a Tech III Power Command, Model 9500, made by MRC. It does have "momentum" on it, but I never use it, because it can easily kill a motor. This power pack is pretty potent. Is this one of the ones on the "bad" list? |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/10/2014 : 02:57:42
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Took the plunge, and ordered a new rear truck for AMTK 68. Its original rear truck has now failed completely, and I tried swapping it with the good rear truck out of AMTK 188, and the 68 ran fine, while the 188 faltered. It'll probably be the middle of next week before the new truck arrives.
Meanwhile, I did another teardown on the failed truck. I took it completely apart. Found no binding at all. Found no broken gear teeth. The top drive gear, which meets the brass worm, does have a lot of lateral play, but it didn't appear to be enough to cause the truck to lock up. So, now, I'm thinking the motor, itself, failed.
I'm now watching AMTK 161's rear truck, because it continues to show signs of impending failure. |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/14/2014 : 06:12:44
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Good news! The replacement rear truck for AMTK 68 came in today (Monday, January 13th), and it did the trick. Popped the bad truck out, popped the new truck in, and off we went. AMTK 68 is running better now than it did when it was brand new.
I'm currently running it in lead and AMTK 161 trailing with my standard nine-car consist. Everything's going great. Acceleration and deceleration are fine now. It seems that the tweak with the wheel wipers did, indeed, help, though I bent the arms out too far and had to bend them back. The main thing is to make sure the center of the wiper sits as flush to the housing as possible, so the electrical contact stays as constant as possible.
Back to the new rear truck for AMTK 68. I did NOTHING to it. Unwrapped it, popped it on, and tested it immediately. Right out of the box, it was really nice. I did clean the wheels on the new truck, as well as the rest of the locomotive wheels, before getting the train rolling.
I was worried about AMTK 161's rear truck failing. It no longer shows any signs of impending failure. I guess the wheels were more fouled than I thought. I'm still experimenting with wheel cleaning intervals, to see how long I can run between cleanings, before the running gets erratic.
I am encouraged. VERY encouraged. |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/20/2014 : 00:33:42
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Things are continuing to go well with these Kato P42s. I started having more trouble with AMTK 161 running erratically. I tweaked around with it, and stumbled into something. The 161's rear truck motor was causing problems, so I took the truck apart again. After (still) finding no binding, I inspected the motor and worm/flywheel assembly. Couldn't find anything wrong. Then, as a last-ditch effort, I looked at the motor's alignment. Front-to-back alignment was fine. Side-to-side alignment was fine. (The motor can't move side to side, because of the cradle housing it sits in.) What I did note was that the motor was slightly askew in a rotational sense, to one direction or the other. I rotated the motor in its shaft, so the leads were directly across from each other, and the surging and lagging just vanished. It was amazing! The engine runs like a charm now... just like the other two units. I am having a GREAT time with these things now. They are smoother than ever.
I'm not sure why rotating the motor made the difference, or, even, IF rotating the motor made a difference. Is it a polarity thing? I have no idea. All I know is it worked.
With both the wheel wiper tweak and the motor orientation tweak, these engines smoothed out and quieted down. Throttle control is wonderful now, and these engines seem less vulnerable to dirty track.
I'm really pleased. It's taken several months to get here, but I like where we've arrived. |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/20/2014 : 06:30:29
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Uh-oh. Spoke too soon. AMTK 161's rear truck is starting to act up again. Its rear axle is starting to stall again in lateral movement. So, the wheel-wiper tweak failed. And, to boot, this engine has slowed down again to the point where it is considerably slower than the other two. Replacing yet another truck/motor assembly is not my idea of a good time.
Sigh. |
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swchief3
Passenger
USA
142 Posts |
Posted - 01/31/2014 : 23:15:34
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Been running AMTK 161 the last few days, in both lead and trail positions, and it's doing much better now. I had to tweak it again, as it got out of adjustment, but it's doing quite well now. That engine is proving to be very finicky. AMTK 68, with its new rear truck, is still running great, and AMTK 188 has been good from the beginning.
Those Heritage units are looking better and better. The phase Vs seem to be smoothing out, the more I run them. This is good. |
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Kato HO P42 Update...Things are looking up...
