Confused Kato Decoders

[ATShinkansen]

Hello,

 

So I’ve picked back up converting my Tomix RailStar 700 to DCC.  I’m hardwiring the FL12 into the cab cars.  I’m still on the first one.  The LEDs on the modified board work just fine when I touch the wires directly to the rails, but when connected to the decoder, only the headlights work, no tail lights.  I thought this might be the decoder itself (I’ve tried two, with the same results), but when I swap the white and yellow wires, I get the same thing, the headlights light up in reverse, but no tail lights on forward.  I’ve seen lately on other models where the decoder needs to “wake up” a bit before the head/tail lights respond as they should.  Could this have something to do with my issue?  I should also point out that the LED for the tail light is a replacement from Circuitron as I shorted out the original.

 

Another issue I’m having is with the EM13 in the motor car.  It ran fine when I installed it several months ago, but now when I apply power, it crawls and rapidly changes direction, as if it has no idea what it’s being told to do.  It continues to do this even when the throttle is set to zero and the direction is set to neutral.

 

 I‘ve already tried resetting CV8.

Edited August 21, 2022 by GCRailways

[Dani]

Hello,

 

If you tried two FL12 with the same result... looks like it's not a problem of the FL12 decoder. If I read it correctly, both leds (head and tail lights) work well when powered directly from the rail current. But connected to the FL12 only the headlights work, even if you swap the white and yellow wires.

 

It would help if you post a photo showing the led board and how is it connected to the decoder, but it looks like you have connected the decoder wire to the postive lead of the tail led. White and yellow wires must be connected to the negative lead of the led. This would explain the behaviour and would be the reason why only the head lights are lit.

 

Normally you have to invert the position of one of leds of the light boards so both have the positive connected to the track current (or the blue wire of the decoder), and the negative is connected to the white or yello wire.

 

About the EM13, I have no clue, but it looks like you have a kind of shortcut in the decoder. Try to isolate it with Kapton tape so the decoder is not touching any metallic surface.

 

I hope this helps!!

[chadbag]

I converted my Tomix Railstar but did not try to use KATO decoders.   For the cab cars I used NGDCC bi-polar decoders.  Something to consider if you get tired of futzing around with the various changed needed to make the standard ones work.

 

With the motor car, do other DCC locomotives or motor cars work fine?  Is it only this one?

 

[ATShinkansen]

I think the cab car issues boil down to the LEDs themselves.  I’m using a Circuitron red 3mm bulb.  (The original burned out because I forgot about making sure there was a resistor along its path.)  I substituted a Digitrax LED for it, and it worked fine.  I tried a second Circuitron bulb, and nothing.  I’d post pictures, but at this point, I’ve taken the bulbs off the board and am testing them straight off the decoder (with a resistor).  I did reverse the red LED and alter the board so that both positive leads are joined.

 

This is the only model I’ve had this issue with.  I figured it was just because it’s Tomix (my only other Tomix train is a KiHa 40, and that will be converted soon after this one).  I’ve got my Kato 500 Series disassembled for reference, as I’m basically wiring it the same way. The 500 runs just fine, though I haven’t had to replace any LEDs.

Edited August 22, 2022 by GCRailways
Clarification

[ATShinkansen]

Also, I guess do I only really need one blue wire between the LED board and the decoder?  Because both tabs are electrically connected on the decoder (makes sense if they’re common).  I don’t know why I didn’t think of that with my other conversions.

[Dani]

On 8/23/2022 at 4:28 AM, GCRailways said:

Also, I guess do I only really need one blue wire between the LED board and the decoder?  Because both tabs are electrically connected on the decoder (makes sense if they’re common).  I don’t know why I didn’t think of that with my other conversions.

 

If you have blue wire in your decoder, you need to connect only this blue to the positive side of both leds, so yes, you only need one blue wire. But you can also feed the positive side from any of the rails if this is easier, it's not strictly needed the blue wire.

Edited August 24, 2022 by Dani

[ATShinkansen]

Okay, thanks.

 

 I don’t know if Circuitron LEDs were simply not intended for DCC use on rolling stock, but I ordered some alternative LEDs from Tony’s Train Xchange in hopes that I’ll have better results.

[ATShinkansen]

New LEDs arrived a couple of days ago, and they work perfectly.  It’s definitely a Circuitron thing.  I don’t know what it is about them, but they just don’t seem to be DCC compatible.  I’m guessing they’re rather intended for control panels?

 

On to the motor car now…

[ATShinkansen]

I figured out what was wrong with the motor car.  The way everything was reassembled over the motor, it created a bulge in the cover.  The erratic behavior was worse with the shell on.  Disassembled and reassembled with care, works just fine now!