TSU Tsunami2 TSU-GN2000 - Help

[Jamesn320]

Hi All,

I'm fitting, well trying to fit, DCC power couplings to some HO locos with TSU tsunami2 decoders.  I’ve managed to get function 5 to work in forwards and function 6 in reverse.  The functions in these boards only put out 1.4v.  Not to worry, I can use at transistor which is activated by the function and draw power form the decoder common and decoder ground.  But!!!!!!  Where is the decoder ground an Tsunami2 TSU-GN2000?

It will be the same positions used to connect a stay alive.

Any help is greatly appreciated!

Cheers,

James

[jdcolombo]

Is that a board-style decoder?

If so, then I think it has a two-pin plug connector for a Soundtraxx "Current Keeper" keep alive next to the motor pads.

One of those pins would be the decoder ground.  I'm not sure which, but it looks from Soundtraxx's wiring diagrams like it might be the right pin (one closest to the motor pads). 

John C.

[Jamesn320]

Hi john,

it looks like this.

[peteski]

If the manual for that decoder doe not show the common (negative, or ground) connection then you can find it on the negative side of the rectifier diodes. Those are the 4 large black rectangular components next to the track pickup contacts (on the right side of the decoder in the photo).  If I see it correctly in that photo, the negative side would be at the diodes closest to the side edges of the decoder, and on their inboard terminals.  But I can't quite see them clearly, so it is not a sure guess.

[Jamesn320]

Hi Peteski, I tried that first.  Tsunami's are odd.  Between the common and functions you only get +1.4v, I guess they are pre resistored down for LEDS.  Between the common and the left of the top diode you get -14v which is odd.  Any others and its about 6 + or -.  If you attempt to power any thing from that -14v all the other LEDS get brighter which tells be to leave the common alone.  The socket, which thanks to John, I now know is for the current keeper should have the proper board common and ground pre voltage drop so I just attempted to measure that, carefully.  But not carefully enough, I think I must have crossed the terminals with the probe as the decoder is now dead and the command station detects a short when placed on the track.  I'm not having a good day!

[peteski]

Hi Peteski, I tried that first.  Tsunami's are odd.  Between the common and functions you only get +1.4v, I guess they are pre resistored down for LEDS.  Between the common and the left of the top diode you get -14v which is odd.  Any others and its about 6 + or -.  If you attempt to power any thing from that -14v all the other LEDS get brighter which tells be to leave the common alone.  The socket, which thanks to John, I now know is for the current keeper should have the proper board common and ground pre voltage drop so I just attempted to measure that, carefully.  But not carefully enough, I think I must have crossed the terminals with the probe as the decoder is now dead and the command station detects a short when placed on the track.  I'm not having a good day!

James, the common connection for the function outputs (the blue wire) is positive not negative (or ground).  Or in this case, if their common is designed to directly drive the 1.5V incandescent bulbs, it will be positive 1.5V. The functions outputs provide a path to ground, not a positive voltage. So are you looking for a common positive or a common ground?

The manual for this decoder might be helpful in identifying that's what.  It might be available for downloading online.

[jdcolombo]

I'll let you and Peteski figure out the electronics aspects.

BUT . . . isn't that a plastic plug on the far left side of the decoder rising from the board?  That looks like the connection for the Soundtraxx keep-alive.  If you are really looking for the negative connection, that's a place to look.

John C.

[Jamesn320]

Hi Peteski, yep common is always positive, but between the negative side and the blue wire (tab) it reads (-)?  As you say the Tsunami decoders are set up to directly drive LEDs.  Useless for anything else.  So the circuit for what I want to do is this hence why i want a clear positibe and negative.  The blue 'tab' will be no use.




I normally used these with ESU or Zimo chips which are much better in my opinion as they are far more flexible in what you can do with them.

[Jamesn320]

I'll let you and Peteski figure out the electronics aspects.

BUT . . . isn't that a plastic plug on the far left side of the decoder rising from the board?  That looks like the connection for the Soundtraxx keep-alive.  If you are really looking for the negative connection, that's a place to look.

John C.

Hi John, yes it is and you are right. But in attempting to check that I think I have shorted the decoder!!!!  As I say, not a good day.  But thanks for the info, that is what I wanted to know.

[peteski]

Hi Peteski, yep common is always positive, but between the negative side and the blue wire (tab) it reads (-)? 

That makes no sense to me.  Unless Tsunami doesn't follow the DCC standard?  But that doesn't seem likely.  I would really have to have the decoder in hand to do some "reverse engineering".

Looking at https://www.soundtraxx.com/manuals/Installation-Guide.pdf (page 20) these decoders seem to have both, 12V and 1.5V positive voltage available.  Terminals 2 and 7 are 12V common, and terminal V1 (on the side of the decoder) is 1.5V common (both positive in reference to the decoder's ground).  The function outputs still provide a path to ground (when activated).

[k27463]

Peteski, the GN2000 is a Athearn specific board with 1.5V outputs for the Athearn bulbs...

james, can you get a better top down photo of the decoder with all the pads clearly labelled?

[peteski]

Peteski, the GN2000 is a Athearn specific board with 1.5V outputs for the Athearn bulbs...

james, can you get a better top down photo of the decoder with all the pads clearly labelled?

That's what happens when an N-scaler tries to answer H0 scale questions. 

The full (12V) voltage, and ground will still be available at the decoder (likely at the rectifier diodes).  And it would make sense if the function outputs were basically providing a path to ground (like in any other DCC decoder).