Kato Mikado jerkyness help needed

[bsoplinger]

I did an install of a Kato Mikado for a customer here and I'm totally stumped. He got it back completely stripped down and taken apart from another DCC installer and so to start I had to put the loco back together. And then put it back together again, properly the second time

It runs just fine, except when it has to pick up the track power itself. That is, if I use alligator clips to jumper power from the track to the frame the loco runs smooth from near stall to breakneck without any hesitation or jerkyness. Soon as I disconnect the clips and try to have the loco run on its own, jerks, hesitations, stops and starts and pretty much any speed.

I'm thinking there's a physical issue involved here, a bent frame, driver out of alignment or somesuch that makes the power pickup temporarily short or disappear. I'm inclined toward disappear, because if it was a short I'd think I'd still see the stutter each time the short happened even when I've got it powered via jumpers.

Any brilliant ideas or suggestions?

Short of just telling him to start over on a brand new one

TIA
Brian

[Powersteamguy1790]

The draw bar from the Mikado isn't properly connected to the tender truck. On the Kato USA website, there is a picture tutorial showing you how to connect the draw bar to the tender truck.

Have fun...

Stay cool and run steam....

[ednadolski]

are all the electrical contact surfaces clean?  no stray lube?

[Chris333]

I imagine you are running it without the tender for testing?  If so and it is an older run you won't be going anywhere. The first run had these horrible strips that stretch out to the driver rims and it didn't touch very well. The newer drivers are made of a whole single piece so they conduct much better.

If the tender is hooked up then yeah make sure the feeler wires at the tip of the drawbar are correct to the locomotives frame tab. Also make sure it is contacting the front tender truck.

I have two of these Mikes in a billion pieces right now 

[bsoplinger]

The draw bar from the Mikado isn't properly connected to the tender truck. On the Kato USA website, there is a picture tutorial showing you how to connect the draw bar to the tender truck.

Good suggestion, but I can't find a tutorial about the draw bar. I decided that the plastic loop end of the draw bar goes on top (when the tender is oriented to be run) of the truck, between the truck and underbody of the tender. The brass pickups go under the truck, into the little notches there, and touch the brass pickups on each side of the truck from the inside not outside of those pickups.

This picture of the part set that is both tender trucks and a drawbar seems to show it oriented just like I said. You can clearly see that the drawbar is on top of the truck and just barely see that the brass 'rods' go under the truck. http://www.katousa.com/images/941032A.jpg

I checked that the tender wheels seemed clean, as are the main driver wheels on the loco itself. No stray lube nor any dirt. The loco as sent back was completely dry, so the only lube is what I added, a drop onto the worm then a bit of running then another drop.

It is indeed a first gen Mikado with those little strips that go to the metal rims of the drivers. Do you think using one of those conductive paint pens where the strips touch the rim would help?

About how I'm running it to test. I removed the body shell (cab, main body and front where the smokestack is). Also the piece on each side that provides the running board and underbody detail. I then have a jumper cable with small alligator clips on each end. One end attached to track and the other clipped to the frame where there is that protuberance to stick the running board/underbody detail piece. The loco then drags the wire along as it moves back and forth on my test track. I do have the tender attached, as that's where the decoder is. I even went so far as to add a second power pickup to the decoder, wired to the lightboard in the loco, in addition to running wires from the brass pickups inside the tender.

When I use the jumpers the loco runs smoothly at all speeds from creep to max. There is no stuttering, no indication that a short is occurring (such as what happens with the G4 drive wheel touching the body). The light stays on and is steady (when running forward). Since this is a sound decoder the sound comes on, stays on, stays consistent at all speeds (well the sound of the chuff advances with speed).

As soon as I remove the jumpers, which means the loco must provide power as intended, via the wheels of the tender and loco I get jerky off then on then off then on movement at all speeds. About the only thing I tried that seemed to make any difference was to set a weight that I had handy from a Kato HO RS3 (probably 2 - 3 ounces) on the front pilot. It teetered quite a bit as the loco ran but it did make it run much more smoothly. But still not nearly as smooth as it did when I was using the jumpers.

[Chris333]

That conductive paint may work, I haven't tried it. I bought the revised drivers from Kato ($20).

Here is the draw bar:


And how to couples to the locomotive:

***The tender is upside down in this photo to show how the contact strips should fit***
Also the trailing truck hooks into a tab on the draw bar.

You may try to clean the frame post where the draw bar connects.

[bsoplinger]

Here is the draw bar:

Are you sure that's the correct way? That isn't like the one brandy new loco I was looking at and it isn't how I hooked up mine, instead I ran that pair of brass wires under the crosspiece of the truck (the bit that goes from sideframe to sideframe and has the hole into it to screw into the bolster on the underframe of the tender) so they touch the brass contacts underneath (relative to the photo) instead of on top as you have them.

Regardless, having it like in your photo didn't help things at all.

I'm still thinking I need to add a .001 brass shim to one of the wheelsets, perhaps the back one, since it has a traction tire it's not like it'll be picking up power anyway

Brian

[Chris333]

That is how this one was when I removed it and how Bachmann locos are as well. I just figured this is how it was, but the way you describe would work too.

I have no idea what is going on... Are the tender wheels dirty? If you pop a wheel out is there a bunch of crud in the axle caps? Can you stick something like a LED on the drawbar and see if it stays lit as you push the tender around? If so the post to on the loco frame could be dirty, you can rub it with an eraser. I have like 3-4 Kato tenders here now and they are all working, but they are all DC. You got me stumped.

[victor miranda]

take the tender trucks apart and clean the fuzz out of the cups and axles.

also take a brightboy to the tops of the truck contacts
and make sure the strips in the tender are functional and contact the truck tabs.

last thing is to make sure the drawbar wires are sprung against the contact points, truck side out,  loco side in.

[bsoplinger]

take the tender trucks apart and clean the fuzz out of the cups and axles.

Did that, not really much fuzz in there but I checked there before I put up my first post here about my problem.

also take a brightboy to the tops of the truck contacts
and make sure the strips in the tender are functional and contact the truck tabs.

I double checked the tender strips, they move freely and are nice and shiny brass vs old penny colored. The contacts were/are clean.

last thing is to make sure the drawbar wires are sprung against the contact points, truck side out,  loco side in.

I'm not sure what this means. The drawbar on the loco end is split around the little nubbin on the bottom of the loco. On the tender side the wires ride against the brass contact strips in the trucks, under the crosspiece (the bit with the hole to mount the truck) with the round plasticy piece over the top of the crosspiece.

I did have some luck with adding a .003 shim to the last (#4) driver, actually 2 shims one on each side of the frame. Now the loco runs OK-ish. Jerks and hesitates every now and then, maybe 1 pass out of 4 on my test track (one pass is a forward/backward run of the 6' long test track). Before the shims I was lucky if the loco would go 2" without a hesitation.

Another point I should maybe offer. Each time there is a jerk/hesitation the sound cuts out and restarts. This is with a micro Tsunami decoder. So that indicates either a complete loss of power or a short. It can't be much of a short because the command station never sees a short, i.e. it doesn't cut out.

And thanks for all the suggestions offered so far. This one is really frustrating me.

Brian

[Chris333]

 ???

I thought you mentioned shims to help get extra traction or something. How did it help the smoothness of running? Is it a electrical or mechanical issue?

I just made a 2-10-2 out of a Kato mike. The forth driver still has a traction tire. The front driver is now geared. Point is I ground and cut the frame many times, but it still ran silky smooth once it was all together.

[Powersteamguy1790]

Brian:

 By telling me the loco runs with a hesitation/jerk tells me that the draw bar is compromised and should be replaced with a new draw bar.

The draw bar is probably distorted/bent due to all the handling that this steamer has seen. Once a draw bar on a Mikado is compromised, the steamer will run erratically. Those are the symptoms of this Mikado.The draw bar is the weak link on a Kato Mikado. I always keep quite a few on hand to service my Mikados should the need to do so arises.

Have fun....

Stay cool and run steam....

[bsoplinger]

By telling me the loco runs with a hesitation/jerk tells me that the draw bar is compromised and should be replaced with a new draw bar.

I trust what you say, I know you've got tons of experience with all sorts of N-scale steam, but...

I did that. I ordered a drawbar (and other things) from Kato's site. Replacing the drawbar made absolutely no change at all in how this thing runs. I should have mentioned that I did put in a new one. I knew I did of course, guess you folks can't read mind, sorry about that Should I order yet another drawbar, could the new one I just got be bad?

I think its a physics issue Chris, because if I run a pair of jumpers and connect them to the tabs that hold on the underside pieces that make up the walkway on the loco (with those pieces removed) and connect the other ends of the jumpers to the track the loco runs completely smooth at all speeds. This tells me that the wiring to the decoder is good since if it was bad or intermittent I'd see that happen no matter how the loco gets power. It also says that there are no shorts occurring as it runs because any short would instantly make the decoder reset itself. Since it runs perfectly with the jumpers it is a pickup issue. The decoder picks up power from both the tender contact strips and the lightboard in the loco. Which makes it seem to me that even if the drawbar was compromised I'd still get power from either the tender strips or the loco itself even without the drawbar's electrical connection. I've cleaned the track a few times now, checked the wheels themselves on both the tender and loco, checked the brass point cups on the tender pickups for lint and stuff, in short done all the 'normal' things I can think of that effect power pickup.

Yet the loco still occasionally hesitates.  :'(  :'(

[3rdrail]

I think we're missing some facts here. I noticed a reference to operating the Mike with the tender but minus the superstructure. No wonder it skips and stalls! The Kato Mike minus the boiler and weights is imbalanced toward the rear. I notice it was stated that things improved with a weight on the pilot.

Kato's engineers are top notch. The whole system is designed to work as a unit, not as a separate underframe and superstructure. Try it completely assembled.

[victor miranda]

hmmmmm
quite the puzzler.

from your description there are not many causes left.

trucks work contacts into tender work
that leaves the drawbar as the problem.
does the loco short.... the jumpers work so a short is not possible,
back to drawbar.

some how some way the drawbar is the problem.

the contacts on the bar are made of wire,
if they get overloaded they will heat a lot,
they lose their temper and big and do not always show drawbar melting.
bend the wires to make stronger contact.

and clean the contact points.

I live with cats and I can tell you the fuzz from then hides pretty darned good
so you may want to check again for fuzz in the pickup cups.
The jumper clearly points to the drawbar however...
v