Need some ideas to improve pickup from Kato Mikado tender trucks

[Bart1701]

I have one of Kato's first run of Mikado steam locomotives. I just installed a Tsunami TSU-750 sound decoder in the tender which is used for sound only; this is in addition to a separate decoder in the boiler that controls the motor and light functions. The sound decoder is constantly resetting itself as the locomotive moves around the layout. From what I can determine, the issue appears to be related to power being picked up by the tender trucks and being sent to the brass contact strips inside of the tender. As the tender moves, it looks like the tips of the brass pieces on the tender trucks that should make contact with the underside of the brass contacts inside the tender is not happening reliably. As the trucks and tender naturally vibrate/wobble slightly when it is moving, the contact seems to get broken quite often causing a decoder reset. This also impacts any power that the drivers would be able to send back to the tender through the drawbar since the front tender truck does not always make reliable contact with the brass contact strip in the tender. As an FYI - The tender still has the metal weight in it that runs along the bottom of the frame.

How would I be able to dramatically improve the reliability of the power pickup in the tender? Installing new contact strips, using some way to extend the tips of the brass piece on the trucks to make a more reliable contact with the contact strips, or some other way?

Thanks,
Bart

[Chris333]

Tender is fine. The first run locomotive drivers barely pick-up electricity. If you go to Kato's site you can buy a new set of revised locomotive drivers for around $20.00.

[Bart1701]

I have already replaced the drivers with the newer revised drivers from Kato a while ago. I am pretty confident that my problem is with the unreliable contact between the brass sideframes on the tender trucks and the contact strips inside the tender.

Bart

[Nick Lorusso]

Add a capacitor to the sound decoder. I have had that problem with sound decoders before.

[Bart1701]

I guess I should have provided more details about the installation    Sorry!

I did install capacitors with this decoder install. I also have used them with other sound decoder installations and they do help immensely!

However, this decoder periodically starts resetting itself constantly as it goes around the layout- so I don't think the capacitors would have enough time to build up much of a charge. My best investigation still suggests that the tender trucks are not maintaining solid contact with the brass contact strips as the tender experiences slight wobbling/movement on sections of the track.

Thanks,
Bart

[spookshow]

I'd check the axle tips and the corresponding dimples in the truck contacts to make sure that everything is clean and shiny. Tender wheels as well.

I've never run into any problems with the conductivity between the truck contact tips and the contact strips inside the tender, but I suppose if all else fails you could go with Victor Miranda's Con-Cor 2-10-2 tender truck mod (IE, add MT springs to the truck contact tips) -



Good luck!
-Mark

[brokemoto]

I had some problems with contact in the tender.  I solved them by adding weight.

[Chris333]

On other tenders that I add Kato trucks to, I just solder wires right to the trucks tabs.

[chicken45]

I listened to Maxcow's advice and hardwired the truck tabs.
I wasn't able to take his advice in hard wiring the drawbar.

[SkipGear]

The phosphor bronze strips in the tender are supposed to act as springs. If they are bent up and not perfectly flat, you will have the problem you describe. The tender in stock form never sets down fully on the bolsters. It rides on the pickup wipers as a leaf spring to help with equalization so all 8 wheels contact the rails no mater how bad the track. You should be able to push down on the tender at it will spring back up slightly. If it doesn't either you either have a ton of weight in it or the leaf springs are bent.

The Kato tender pickup system is the best there is when it is assembled correctly. My guess is you soldered direct to the Pb wipers and it warped them so they are no longer doing the proper job.

[randgust]

Kato does things the same way in the 'critter' chassis - the 11-105, and in the cupola caboose.    I only have two tenders, but I've done probably 50 11-105's and a dozen cabooses.

The trick is to remove the wipers and rebend them like SkipGear said.  You can also add weight, in effect, that puts more downward force not on the wheels but on the entire wiper > contact > axle > wheel system.  When it works right it equalizes contact and springs the wheels onto the rails, unlike any other system ever designed, and is significantly better.  With the tender sitting on the rails, you 'should' be able to pop an individual wheel up with tweezer points and feel the spring action pushing back down.  If you can't, its either hung up in the slots or the wipers aren't bent down enough to hit the nubs.   You just keep tweaking the contact bend until you max it out so that it is balanced.

I also do two more things to mine - I hit the axle ends and the contact 'nubs' with Atlas conductalube, and I also periodically polish the wheel treads with a felt buffing end at medium speed in my dremel.  That brings them back to factory shine.  That makes the second biggest difference to tweaking the contact bend.

I've had to repair several customer attempts at soldering jumpers and bypassing the wipers.  If you do try it, don't do it in an assembled frame - do the tabs entirely out of the trucks as it is all too easy to melt the plastic slots, trucks, etc.  But without downward force, there is no equalizing, and while you may beat the wiper/nub problem now you'll have erratic contact on the axle ends.   I've concluded it's ineffective overall.

I've also hardwired around my wire-spring drawbars - the Kato Mikado, Atlas 2-6-0, and Atlas 4-4-0.  It's worth it.

[Chris333]

I've had to repair several customer attempts at soldering jumpers and bypassing the wipers.  If you do try it, don't do it in an assembled frame - do the tabs entirely out of the trucks as it is all too easy to melt the plastic slots, trucks, etc. 

This is what I do (take them apart to solder)
https://picasaweb.google.com/ErieChris333/MaPa280#5493993509572427650

[SkipGear]

I have a beautifully painted and detailed Mikado with a decoder installed that was given to me because of the same problems mentioned above. When I dug into it, the problem was somebody decided to nix the wiper setup and hardwire the trucks to make installing the decoder easier. I rebuilt that tender 3-4 times with different wire and configurations and never got it to run smooth. I finally stuck a whole new tender on it. After that, instantly butter smooth and no problems. I will only hardwire truck pickups if it is the last resort. The spring wiper setup is soooo much better when setup correctly.

I went to great lengths on my 2-10-2 tender to get that system in the vanderbilt. It was worth it, even only on the front truck of the tender.

[mmagliaro]

Since my name got mentioned, I wanted to clarify something.

Although I do often hard-solder super flex wire directly to Kato trucks, I do this on tenders that do not have the
sprung bronze wiper system in the floor, and I run the wires directly to the motor.

In a stock Kato Mikado tender, I would not do this.  I would solder leads to the bronze strips and run them to
the motor to bypass the drawbar,
which is sometimes a problem, but that floor/truck pickup system is excellent.  On that point, I agree with Tony.

In the problem case at hand, I am inclined to agree with others in here; those strips are probably bent upward, or not bent down flat enough. to keep good contact on the truck tangs as the trucks swivel and rock over the track.

[Bart1701]

UPDATE - Problem solved!

My Mikado is steaming around the layout smoothly again - thanks to all of you for your suggestions. I did the following 3 things and then tested the locomotive and it was working perfectly - so, I can't determine whether one of these things or some combination of the three was necessary:

1) I took the brass contacts out and made sure they were flat. Some distortion was apparent after handling them and soldering the decoder wires to them.
2) I took small strips of thin plastic and glued them at each of the channel ends on the bottom of the black plastic piece in the tender that secures the contact strips down and holds the weight in place. I figured these would push down slightly on the contact strips to make better contact with the brass tips coming up from the truck sideframes.
3) I cleaned the tender wheels. Under closer observation, I could see some crud on the wheels.

I'm betting that the crud on the wheels was the primary cause of my problem - sometimes the fix to a problem is the most obvious and easiest to fix. I have to get better at looking at the condition of the wheels first! I also think that the re-shaping of the strips was also necessary.

Thanks,
Bart