# Kato Runs Slow/Erratic



## edwards (10 mo ago)

I have a Kato SD40-2 that runs very slow max speed and does not begin to move until throttle is about 25% or more. Further, it slows at about 50% throttle and them jumps back up at about 60% throttle. And even further, the speed steps on my throttle jump by 3s. For instance, speed steps 3, 6, 9, 12, 15 and so on in lieu of 1, 2, 3, 4, 5,,, and so on. I have changed from a Digitrax decoder to a XL Systems decoder and the same issues occur.

Anybody know what's going on??


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## CTValleyRR (Jul 26, 2014)

What DCC system are you using? The jumping of speed steps is fishy, to say the least. It might be the decoder, but it's more likely that something is wrong with your DCC set-up. The fact that you're talking about throttle percentages has me scratching my head, too.

However, it also sounds like the speed tables and min /mid / max voltage settings are all hosed up. If you set these values, you can just undo your changes, but if someone else programmed it, then It is probably worth just doing a factory reset (set cv 8 to a value of 8 and start over). If no one has ever set them, then you need to. Min voltage is adjusted so that it just crawls in speed step one. Max voltage should be the highest setting allowed to take advantage of the full speed range of your loco.


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## edwards (10 mo ago)

No, nothing like that. I use JMRI and all my other locos work properly and I know how to program the speed tables. This Kato had a Digitrax decoder and have the speed step jumping by 3s (and I referenced by percentages because the steps don't follow normal 1, 2, 3, 4 steps). But here is the weirdest part...I CHANGED to a BRAND NEW decoder by a DIFFERENT manufacturer and the loco still acts wonky. I am wondering if a wire on one of the motor stators broke? But it seems the motor just would not work at all in that case.

I have also adjusted the Back EMF all sorts of ways.


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## CTValleyRR (Jul 26, 2014)

Unless you have another loco with the SAME model of decoder, the fact that your other locos work and that you know how to program speed tables doesn't really matter. How is it done on THAT decoder. Or those.

You're right that if there were a mechanical failure, then it just wouldn't run at all. This issue is digital, ergo suspect the programming. I don't use JMRI myself, but I have heard that people have had issues when trying to copy the same set of CV settings to different locos with different model decoders. When ever you're troubleshooting, forget everything you are assuming to be true, and check it, then test it. Change only one variable at a time, and make sure the loco behaves properly before you change the next one.


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## Oomowmow (10 mo ago)

edwards said:


> I have a Kato SD40-2 that runs very slow max speed and does not begin to move until throttle is about 25% or more. Further, it slows at about 50% throttle and them jumps back up at about 60% throttle. And even further, the speed steps on my throttle jump by 3s. For instance, speed steps 3, 6, 9, 12, 15 and so on in lieu of 1, 2, 3, 4, 5,,, and so on. I have changed from a Digitrax decoder to a XL Systems decoder and the same issues occur.
> 
> Anybody know what's going on??


I just saw this thread, but I thought I'd share a similar problem with an older kato GP38-2. It's not DCC, but it's having similar issues. It speeds up all by itself and then slows way down. Sometimes it almost stops. It runs very smoothly the whole time, just won't stay at a consistent speed. I've cleaned and lightly oiled it to no avail. All my other engines run fine, so it's not the track or power pack. If your still having an issue... maybe it's the loco itself. I'll be taking mine in to have it looked at eventually.


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## pmcgurin (Sep 7, 2010)

I don't know if this will help you, but I have had performance go downhill with Kato F series and Atlas and Kato fou axle road switchers and found that replacing the trucks cured the problem. The locos in question had quite a bit of use at the time, four or more years at least. A hobby shop expert put me on to this.


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## Oomowmow (10 mo ago)

pmcgurin said:


> I don't know if this will help you, but I have had performance go downhill with Kato F series and Atlas and Kato fou axle road switchers and found that replacing the trucks cured the problem. The locos in question had quite a bit of use at the time, four or more years at least. A hobby shop expert put me on to this.


That's interesting. I've wondered if there's a connection issue. Although my GP38-2 was allegedly new old stock when I got it, and it looked clean when I opened it up. still, there's something wrong. I've really got to get it looked at, there's a place not too far away that has a guy that repairs locos.


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## pmcgurin (Sep 7, 2010)

Just tonight I replaced the trucks on a Kato F3A from their first run of these with spare trucks (new) that I bought years ago. Before I replaced them, this CN F3 couldn't pull five Con Cor passenger cars at full speed, but now it's pulling them at slow speed, about 25% power (DC). The Con Cor cars have weighted bottoms and are heavier than most other passenger cars I have. These old trucks have metal frames instead of later ones with plastic frames. I think that CN olive and yellow F3 is of a similar era as the GP38-2. Not sure of that.


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## Oomowmow (10 mo ago)

pmcgurin said:


> Just tonight I replaced the trucks on a Kato F3A from their first run of these with spare trucks (new) that I bought years ago. Before I replaced them, this CN F3 couldn't pull five Con Cor passenger cars at full speed, but now it's pulling them at slow speed, about 25% power (DC). The Con Cor cars have weighted bottoms and are heavier than most other passenger cars I have. These old trucks have metal frames instead of later ones with plastic frames. I think that CN olive and yellow F3 is of a similar era as the GP38-2. Not sure of that.


My GP38-2 is from the first run of Kato USA in 1987, so it's old.


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## CTValleyRR (Jul 26, 2014)

Oomowmow said:


> That's interesting. I've wondered if there's a connection issue. Although my GP38-2 was allegedly new old stock when I got it, and it looked clean when I opened it up. still, there's something wrong. I've really got to get it looked at, there's a place not too far away that has a guy that repairs locos.


The first thing you need to do before putting NOS (new, old stock) into service is completely clean and relubricate all the drive train components. Petroleum-based lubricants gel and harden over time, and running a loco with insufficient lubrication can actually cause damage to drive train components.


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## Oomowmow (10 mo ago)

I didn't see anything crusty when I opened it, but it did look dry. The problem came gradually, after I'd taken what I thought should be all the right steps. I dunno, I'm stumped.


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## pmcgurin (Sep 7, 2010)

something you should be concerned about is electrical pickup through the trucks to the frame to the motor. Make sure the contact surfaces are not oxidized. Clean them. I do not know what the trucks are like on the GP38-2, but the 1988 F3 Has trucks with a split metal frame that conducts to the frame in lieu of the later trucks with coppery wipers. Either way I had to take an eraser to the contact areas. I was afraid contact cleaner might damage plastic. I found this to be important to maintain performance. As a note, I replaced the trucks on my 1988 CN F3A because I had had rhe spares for twenty years. If you do not have spares on hand, you might not be able to get any.


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## Oomowmow (10 mo ago)

pmcgurin said:


> something you should be concerned about is electrical pickup through the trucks to the frame to the motor. Make sure the contact surfaces are not oxidized. Clean them. I do not know what the trucks are like on the GP38-2, but the 1988 F3 Has trucks with a split metal frame that conducts to the frame in lieu of the later trucks with coppery wipers. Either way I had to take an eraser to the contact areas. I was afraid contact cleaner might damage plastic. I found this to be important to maintain performance. As a note, I replaced the trucks on my 1988 CN F3A because I had had rhe spares for twenty years. If you do not have spares on hand, you might not be able to get any.


I'll take another look at the trucks contact points. It didn't look like a split frame tough, which is unusual.


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## pmcgurin (Sep 7, 2010)

On spookshow.net there is a page on Kato GP38-2: Kato (Japan) EMD GP38-2 (spookshow.net) 
that has some interesting info on this model, if you haven't already read it.


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## Oomowmow (10 mo ago)

Oomowmow said:


> I didn't see anything crusty when I opened it, but it did look dry. The problem came gradually, after I'd taken what I thought should be all the right steps. I dunno, I'm stumped.


Well, here's an update on the kato GP38-2. It continued to get worse, even though I inspected the pickups on the trucks and cleaned them. It would speed up so fast I thought it would derail, and then it would almost completely stop. I talked to an engine repair guy, and we agreed if it was a contact problem it would slow down only, not speed up. He also told me this particular run (the first model released by kato usa in '87, before which they were sold through atlas) was more prone to shorting out over time. That in fact is probably what is happening to mine. The motor is dying. So, anybody got an old kato motor from '87 lying around they'd like to sell? 😐


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## pmcgurin (Sep 7, 2010)

I don't have your model, the 1987 GP38-2, but I have some older Atlas and one of my 1988 Kato F3A that tend to screech and have halting performance at slow speed, about 20% power on a Tech II Dualpower 2800 transformer. At higher speeds these work OK. These are annoying with the screeching and jerking performance and I am sure they are on the way out. I have about six of these 1988 or 1990 Kato F units, all Canadian National green and yellow F3 or red and black and white striped F7 that are still fine. Three of the green and yellow 1988 F3s croaked, and what I did was to buy some DCC-ready F3s from the early 2000s release, and use these later mechanisms in the old green and yellow F3 A and B shells. So now these are DCC ready, and maybe doing something like this would be an option if you like the GP38-2 enough to use a DCC-ready mechanism in it. Just an idea, but I found it useful, because I have a ConCor passenger train in green, and Kato hasn't to my knowledge remade the older green and yellow F units. So, you might want to put a newer mechanism in your GP38-2.


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## pmcgurin (Sep 7, 2010)

I will add that Kato's newer mechanisms are lighter generally, and they run more quietly and with more pulling power. I bought several of the newer F3 units around 2007 and used the mechanisms in F units I wanted to keep using. I only bought a couple of road switchers, but they run very well, an SD40-2 and an SD70 MAC.


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## Oomowmow (10 mo ago)

Yeah, that's the plan. I'll be keeping it around, so if I find a running unit for a reasonable price that the shell would fit, I could resurrect it. 
Most of my locos are Kato, and all Are much newer than the jeep 38, And they all run flawlessly.


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