Kato Mikado issues (resolved)

[SkipGear]

B&O S-1 - (based on a Kato Mikado frame)

http://www.trainboard.com/railimages/data/1204/S-1_Final_Shots_4.JPG

http://www.trainboard.com/railimages/showgallery.php/cat/1204

[timwatson]

That's a beautiful loco dude. That's heirloom quality for sure. Thanks for sharing it.

[peteski]

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.

Tim,
thanks for following through and documenting the fix.  it is always nice to find what fixed the problem.

I'm not trying to be a pain, but some things don't add up to me. First of all, it seems like your model had the original drivers with a contact strip in the back of the driving wheels.  As it was mentioned, those were prone to having a poor contact.

Even if the crank pins were touching the contact strips in the back of the wheels, the only thing that the crank pin would touch is the siderods.  The siderods are electrically isolated from every other part of the model except for the other crank pins.  So even if one or more crank pins were shorting to the contact strips on the back of the other drives, that would not create a short.   However, if the siderods were conducting current between the drivers through the crank pins (if the drivers themselves had bad connection between the contact strip and the metal tire), that could show up as sparking around the crank pins.  I suspect that your model was not shorting - it seems to me that it had a problem with intermittent open circuit.

Either way, the result was a stalling loco. But to me it is important to try to figure what was the problem. Maybe I'm that way because I troubleshoot things for a living. 

[cokeslinger]

http://www.tcsdcc.com/public_html/Customer_Content/Installation_Pictures/N_Scale/Kato/USRA_Heavy_Mikado_Locototive/Mikado.html


this is one way you can install the decoder

[timwatson]

Peteski I have no doubt the circuit was open on the one side. They were indeed the old style drivers. The new drivers fixing the problem proved that. I just tested the driver I thought to be offending one and it was fine. No shorts. My caveat here is I did test these off the loco. So it wasn't a pure test. I'm not taking the new ones off and putting the old ones back on to retest in the name of science.

So case closed on that issue. There were a few places I believe that driver could fail but would be few and far between.

The shocking issue:
Even after the new drivers were installed picking up the locomotive with my hand wrapped around it touching both sides of the siderods did cause another shock. Having seen how the engine is built I now believe it was ME causing the short when I picked it up and the open circuit issue was just another thing that was happening.

I've never seen a  loco that carried current on the siderods so the "regular stuff I do - picking up a steam loco by its drivers" obviously won't work with this loco.

This is my prevailing theory currently anyway. I hope that helps.

[SkipGear]

Tim,
 Picking up a steam loco by the drivers is a bad habit. I make it a point to avoid any moving parts when picking up a loco. As a prime example, a buddy with an Athearn Challenger had it suddenly start derailing at a show. He had no clue why. He brought it to me the following week and it turns out that it had derailed due to an improperly thrown switch and rolled over. He had picked it up by the drivers to re-rail it and in the process squeezed the valve gear hanger on the front engine. This caused inteference on curves and cause the derailing. It took an hour of watching the loco to figure out. It was only bent about .010" inward but that was enough to make a difference. He is a very careful modeler so it wasn't a result of ham fisted handling. He just grabbed the loco by the wrong part.

When I pick up a loco, it will be by the tender and the steam chests or boiler.

[mmagliaro]

Tim,
 Picking up a steam loco by the drivers is a bad habit.

...

+1
Keep hands away from all those delicate moving parts alongside the drivers, especially the valve gear.  The story Tony relates about bending a valve hanger has happened to me--- (more than once... oh, the shame)
 

[timwatson]

Great advice guys. I'm happy to heed the advice of those who have made the mistakes I am bound to make.

Question is will I actually remember when I have 2 trains behind me and other operators tapping their feet? I'm getting further from 40 by the minute. o.0

[timwatson]

I am posting this for the search engines to find because I am sure someone else will have a Kato Mikado that starts acting very erratically and shorts out on corners like mine did.

So I only thought my Kato Mikado short was resolved. I got the new decoder installed and lo and behold it starts shorting out again. Well this time I knew the engine worked without the tender because I tested it. So I had a place to start. I checked the drawbar and started covering it with kapton (in only a small section). Worked great one direction not the other. More kapton tape on the underside of the frame was added and VOILA she's working again.

So IT was a SHORT and the issue was in the drawbar coming from the tender to the loco frame. The metal wires in the drawbar were shorting on the underside of the locos frame as shown in this picture. A little kapton tape on the underside of the loco was the final fix for the issue.

With the decoder in it's running excellent.

[strummer]

Riddle answered,problem solved.

That drawbar issue is a good thing to know about...

Mark in Oregon

[peteski]

Good detective work Tim. Thanks for posting the info.

[rogergperkins]

About 8 or 9 years ago, I tried to exchange a tender with Baltimore and Ohio lettering with the tender on an early run Kato Mikado.
The result was the locomotive ran fine until it came to a curve, then it stopped. 
The problem per Kato USA was in the draw bar harness wiring. Sent locomotive to Kato USA; it was repaired and runs fine.