Hardwiring a Tsunami-equipped Loco - Success then Failure

[yvesmary]

I tried my hand at hardwiring an LM-2S into a Tsunami-equipped loco. I knew I'd have a rat's nest of wires but since all the wires are red or black I wanted to make sure I soldered the right wires to the harness. As I unsoldered each wire off the decoder I soldered it to the appropriate colour of the harness wire following the diagram in the LM-2S sheet.

The wiring for the rail, motor and speaker was pretty straight forward but I wasn't sure about the LED's.

Following the Decoder Wiring Diagram I unsoldered each wire as shown on the bottom of the Diagram and added a 1K Ohm resistor and also the Back-up Light shown at the top and soldered it to the module harness. I left the Ditch Light wire off as I don't have them on this loco.

That left me with 4 wires which I bundled up and soldered to the Blue common wire: on the Diagram they are labelled Back-up Light +3V, two +3V wires and the 4th is from the strobe light which is mounted inside the shell. That wire on the decoder was soldered on top of another wire on the +3V tab.

One puzzle I had was with the Class Light A and B. They're each soldered to the decoder with a 100 Ohm resistor. I didn't know whether to leave them on or not. Then I decided to remove them and add the usual 1K Ohm resistors. I could live without them if they didn't work.

So I put the loco on the track like that and powered up. The HC-2 found the product. I pressed the engine icon and it fired up. Then the horn and the bell and the headlight (and dimmed) and the back-up light.

Wow, I thought. So then I turned up the throttle and she died.  I unplugged the harnesses and tested the module on another loco and got a no product found. It's dead.

I almost forgot. On the decoder diagram it shows the speaker wires attached to a plus and minus tab. I'm not sure if my wiring corresponds to that but I didn't think it mattered for speakers.

I couldn't find any loose wires that might have shorted out so can anybody see where I might have gone wrong from the above.

Thanks
Yves in Alberta

[KPack]

Yves - plugging module into a different loco and searching for using "Find Product" will not show anything, as the module has already been found and loaded into the HC.  If you want to test the module's vitality you can plug it into another locomotive, and select the new module by going to the new locomotive that was created under the locomotive list.

It doesn't matter which way you have the speaker wires connected. 

The only way I can think that the module would fry upon trying to move would be if one of the motor wires was incorrect.  It shouldn't be the power wires as those had to have been correct for you to get as far as you did.  When I say one of the motor wires, what I mean is that one of them may actually be wired to something else and not the motor.  It makes no difference if you have the motor wires reversed....it'll just make the motor run backwards, but that's easily fixed by pressing a button on the HC. 

I have had one module spontaneously fail.  When I sent it back to Ring, they found there were 3 very small pieces of loose solder inside (not from me) and one of them must have caused a short and fried the board.  They replaced it at no cost.  If all else fails, I'm sure Ring will take care of you.

-Kevin

[Alan]

That left me with 4 wires which I bundled up and soldered to the Blue common wire:

Blue common is actually Vcc (+), not Ground (-) as is commonly associated with the word common. Anything hooked to the blue wire must have sufficient resistance to ground to limit current below LM limit.

[Dean]

It might sound like a lot of work, but I would unsolder everything after making a diagram of the wiring. Then just connect the black and red to the track power and the orange and grey to the motor. Now try to run the engine. If the engine runs, then connect just one more device and test it. Do this for each device on the engine. This way you will know where the problem is.
If the engine doesn't run, the decoder might be fried. Double check everything and try again. Try deleting the decoder from the HC-2 and then have the HC-2 find it again.

[Alan]

That left me with 4 wires which I bundled up and soldered to the Blue common wire:

Blue common is actually Vcc (+), not Ground (-) as is commonly associated with the word common. Anything hooked to the blue wire must have sufficient resistance to ground to limit current below LM limit.

I wrote this not so much as a solution to your problem, but rather as an explanation of the differences between RP and Tsunami light connections and your uncertainty about resistors. The Tsunami board is labeled +3V on its lighting outputs. RP LM is +15V (or whatever track voltage is) on its lighting outputs. That is why different resistor values are needed.

Assuming a LED forward drop of 1.5V and a desired current of 15mA:

   

As you can see the 3V Tsunami allows you to use tiny 1/8W resistors while RP requires larger 1/2W resistors. Both arrangements will light the LED to the same brightness. The low volt output is kinda nice. Wish RP did this.

The bit about the blue wire is a lot of people automatically assume 'ground' negative when they see 'common'. The blue RP LM wire is V+. Each lighting output is a switch to ground (current sink). Mostly an FYI since it doesn't matter which side of the LED the resistor is placed on.

[yvesmary]

Kevin

The only way I can think that the module would fry upon trying to move would be if one of the motor wires was incorrect.

The loco ran fine when I had DCC so I assume the motor wires are correct.

I will try to delete the loco from the HC-2 and do another "find product" and see what happens.

Alan

Blue common is actually Vcc (+), not Ground (-) as is commonly associated with the word common. Anything hooked to the blue wire must have sufficient resistance to ground to limit current below LM limit.

Sorry, I'm not sure what that means. Is bundling up the 4 wires and connecting to the blue wire how it's done? If one of the 4 wires somehow is not connected would that cause a problem or just make that LED not work? Also if it makes a difference the 1K Ohm resistors I used are 1/4 W. Electronics are not my forte. You're knowledge (from reading your other posts) makes me envious.

Dean

It might sound like a lot of work, but I would unsolder everything after making a diagram of the wiring. Then just connect the black and red to the track power and the orange and grey to the motor

I was thinking along those lines. If I did fry the module I'd be leery about trying another one unless I knew that if I make a mistake with a next step that it just wouldn't work and not short the module.

So I will test the module tomorrow. If it's good I'll start over. If it isn't I don't know what I'll do. I would hate to kill another one.

Thanks all for your help.
Yves in Alberta

[Alan]

Is bundling up the 4 wires and connecting to the blue wire how it's done?

Yes, providing no wire in the blue bundle goes directly to a light output (green, white, yellow, or violet) without passing through a resistor and a LED (or bulb) on the way i.e. no short circuits between the blue wire and the G,W,Y, or V wires.

If one of the 4 wires somehow is not connected would that cause a problem or just make that LED not work?

The LED would not work. No other problem.

1K Ohm resistors I used are 1/4 W

It is good practice to never use a resistor at more than 60% of its rated power. Using a 1K resistor at 15V = 0.225W. Your 1/4W (0.250W) resistor is operating at 90%. Chances are there will be no problem. Just be aware you are on the ragged edge of resistor power handling.

[yvesmary]

Alan

It is good practice to never use a resistor at more than 60% of its rated power. Using a 1K resistor at 15V = 0.225W. Your 1/4W (0.250W) resistor is operating at 90%. Chances are there will be no problem. Just be aware you are on the ragged edge of resistor power handling

Okay, now I see. I always wondered about the difference between wattages of resistors. Thanks.

I'm a little relieved today. I tested the "dead" module in another loco after deleting it from the HC-2 and it worked. The lights worked and it ran forward and backwards fine.

I checked all the wires again and everything seems good. So I'll hook the harnesses back up and try it again.

Yves in Alberta

[William Brillinger]

FYI: If anyone in Canada needs to return a module to Ring, and does not want to send it through customs, contact me about getting it across the border for you.

[yvesmary]

Will keep that in mind. Thanks Bill

Yves in Alberta