Kato Mikado issues (resolved)

[timwatson]

I have searched the web and various forums and I have yet to come across an issue like the one I'm having so I'm hoping you all can help shed some light.

I have a Kato Mikado that I got on EBay, I'd guess its one of the earlier runs (it didn't have a traction tire).

Anyway it appears to have a short somewhere in the drivers (I've tested the tender) and when I went to test it things got more weird. The traction tire driver (i got it new and recently just placed it on) on the right side turns out to be the only driver that picks up any current on the right side. The left side driver wheels are all conducting electricity like I would expect but not the right side. I thought both sides would be conducting electricity but they aren't. Now the left and right I speak of is when it's upside down and the cow catcher is pointed "north".

Anyone know what's going on or experienced anything like this??

It had been working fine until about a month ago. When it started going around a curve is when it first started shorting out (only in one direction). It got worse recently and now even on a straight it's shorting. It's been a great puller so I want to bring it back from the dead. Just not sure where to start.

[superturbine]

Just in case.... Consider calling kato tomorrow morning and Ording new drivers, they still have full sets in stock.  Now have you pulled the drivers out and actually tested them individually.  It sounds like you have, try cleaning the drivers.... Really well.  The kato drivers transfer power via a copper strip at the back of the driver from the tire to the bearing box.  Is the driver really clean at the bearing box to driver intersection.  Also, The frame spacers are all in place right.

I am a little perplexed tho.... If the drivers are not transferring power how do you have a short.  Is this engine dc or Dcc?  Do the drivers show any sings of heating?  Trace back, test for power at the bearing box then at the Axel then at the copper stip at the back of the driver.

[peteski]

I think that some things should be clarified.  First, many people say that something is "shorting out" where they mean "open".  Is your locomotive actually shorting out  across the track (tripping the throttle circuit breaker)?  Or does it simply stall?

Due to the model's construction (split-frame), having drivers short would be very unlikely.  Each driver is attached to a half-axle. These are joined together in a plastic tubular axle without the half-axles being able to touch (and short). Since each half of the frame is the same polarity as the wheels on that side, there is no chance of a short there either.

Have you tried running the loco without the tender and drawbar?  Since the problem started before you installed the traction tire driver I won't ask you to replace it with the old driver.

There were two types of drivers for this loco. First had a separate metal tire and there was a brass "spoke" which connected the tire to the metal center.  Newer drivers have the wheel center and the tire turned from a single piece of metal disk. the back of it is cross-shaped and the spokes in the front are a cosmetic insert.  But both types could have been made without a traction tire driver.

[SkipGear]

The early drivers had a problem with conductivity, just as you are experiencing. Replace the drivers with the revised set and you should be OK. The seprate wheel center and rim relyed on a friction contact between them and all it took was a little corrosion or a short on a turnout to cause the connection to break down. I have on first run Mikado that has the same issue. Many people didn't notice it because the tenders picked up so well that it masked the problem. This one has a botched DCC install that the previous owner removed the pickup leaf springs in the tender and soldered wire direct to the trucks, pretty much ruining the whole design of the mechanism. This is how I found out that the drivers were not picking up very well either.

[Chris333]

This is an old driver:

Those finger go out and touch the rim, but it rarely works.

The newer drivers are solid.

[rogergperkins]

My plea to you; contact KATO USA about the problem with the locomotive.
I have 5 of these 2-8-2 from various runs.
I am very pleased with KATO USA willingness to assist.

[timwatson]

Thanks gents for the suggestions. Chris you know me, a picture is worth 10,000 words so thanks for the visual. Sounds like the easy way out is to order new drivers.

Peteski it is a short, because when it was going around the curve I could see the spark coming off the second or 3rd driver and when I picked it up it actually shocked me!!

You all have given me plenty of ammo to get this fixed.

[superturbine]

Sounds like you might still have a shorting problen once the drivers are replaced.  Is the engine DC or Dcc.  This is likely the cause of thw drivers failing.

[peteski]

Thanks gents for the suggestions. Chris you know me, a picture is worth 10,000 words so thanks for the visual. Sounds like the easy way out is to order new drivers.

Peteski it is a short, because when it was going around the curve I could see the spark coming off the second or 3rd driver and when I picked it up it actually shocked me!!

You all have given me plenty of ammo to get this fixed.

Tim,
I have no doubt that you'll get this fixed. After all, the loco has a very simple (electric-wise) design and there are probably tens of thousands of these locos out there running perfectly well.

I'm also not trying to be argumentative but you got shocked?  What part of the model actually shocked you?  I would have expected that you lifted it by the plastic (insulating) boiler.  Also, the voltages used in model trains (12 volts) are generally too low to be felt by a dry human hand.  Unless you had a moist hand?  Only time I feel a slight tingle is when I touch the bare frame halves of a DC locomotive running at full throttle and I feel the kick of BEMF when I lift the model off the track.  The motor in that instance sort of works like one of those joke buzzers.

Could the shock been simply a static electricity discharge?  I'm, in Northeast US, where this time of the year the air is very dry. I constantly get shocked by touching metal objects. Friend of mine has a carpeted floor in his layout room and we constantly get shocked by touching the track or metal parts of the locomotives.

Is your model DC or DCC?

[mmagliaro]

A spark still doesn't mean a short.  It could only mean the engine lost contact, and just as you lifted it,
you wiggled a driver enough to get one of those flakey bronze strips on the back of a wheel to touch,
and it sparked.

Put an ammeter in line and run it.  When it stalls, see if the ammeter reads zero, or really high.  That's the only
way to know if you have a short (assuming you don't have any overload light or other indicator on your
power supply).   You could also run another engine at the same time and see if they both stop when this
one does, which would also be a pretty good indicator of a short (unless you have multiple DCC zones and
the engines are in different zones).

Yeah.,.. is this DC or DCC?

[superturbine]

  I think he is right, reason being- having all the engines drivers fail on one side, Tim saying he sees sparks, it started doing this in curves, sounds to me like he may actually have a Short. Do the sparks come from the drivers on the side that is dead.  If the engine is DCC all of the stated symptoms could be possible.  This engine is not know for power pick up problems.  I seriously doubt sparks are caused by a lack of power pick of from a kato mikado with the excellent power pick up of the kato tender attached.     

[SkipGear]

  This engine is not know for power pick up problems.  I seriously doubt sparks are caused by a lack of power pick of from a kato mikado with the excellent power pick up of the kato tender attached.     

The pickup problem is a known problem with the first run loco's. That is the main reason for the revised version of the loco and why Kato offers revised driver sets as a spare part. As you said, many people haven't bothered with fixing it because the tender pickup usually masks the problem. The early tender and drawbar was also revised so there was the potential for problems there.

[timwatson]

Alright gents I have an update on the Mike. Many thanks to all of you for the advice, you guys are great.

It was the drivers.

I ordered the new driver set and they "eventually" arrived from Kato. I installed them tonight and lo and behold it runs like a top again (although that eccentric crank pin was crazy hard to get back in). The thing runs excellent across switches no tender installed so something was up with the drivers. I may inspect (tweak) them later in the name of science to see what the cause of the short was. I honestly think it's something to do with the way the front driver is engineered. I think the pins that hold on the side rods touched the copper piece and that copper was touching the axle. That's my prevailing theory anyway.

Having disassembled this thing it really is quite a feat of miniature engineering (I have disassembled many steam locos before) this one is certainly a different breed. I will certainly be purchasing more.

Next up a decoder install. So yeh it "was" DC. 

Has anyone taken one of these little monsters all the way apart? To install the decoder I know i don't have to full disassemble but I was going to make sure the short was fully cured.

[SkipGear]

Sort of an exploded view.



Disregard that extra set of drivers and gears.

[timwatson]

Disregard them I think i will admonish them! That's a very cool build and most excellent view Tony. Many thanks. I'm going to file that away.

What kind of 2-10-2 was/is that?