Mysteries of the new LokSound in the Intermountain SD40-2

[peteski]

Hi Peteski.

I think you're right about the positive/negative.  I can certainly test continuity, but how to I check for the negative output (dark blue line) with a multimeter?  I assume I connect the positive lead of the meter to one of the track power tabs - easy.  Then what?  And what am I looking for?  A specific resistance? Or should I do this with power feeding and look for a specific DC voltage?

Thanks for your help - this is the last piece of the LokSound mystery!

John C.

John,
If you are willing, it would be easier if I had a chance to fondle the decoder in-person. PM me if you are willing to send it to me.  I would give you additional direction if this appeared to be a simple bridge rectifier, but I'm really puzzled to the components I marked in yellow. And looking at a photograph is not giving me enough information to try to figure them out.  It seems like there might be some additional circuitry within the rectifier area which I have never seen before and I really don't feel comfortable giving possibly incomplete or false info.  I don't want anybody to blow up their decoder.

As why ESU did not provide pads to add a (real) keep-alive circuit, it seems fairly clear to me: They did not think that these narrow-hood decoders will ever be installed in a model which has enough room for the circuit.  I think that to them adding a smaller value (like 470uF) cap is not really a valid or worthy solution.

[jdcolombo]

Happy to send the decoder.

I sent you a PM.

John C.

[Dksw]

I may have missed this, but will this decoder be drop fit into IM's N scale tunnel motors & SD40-2W, same chassis is it not more or less?

David

[jagged ben]

I may have missed this, but will this decoder be drop fit into IM's N scale tunnel motors & SD40-2W, same chassis is it not more or less?

David

No, not the same frame.  It will not drop into previous releases of tunnel motors or SD45-2s.  (I'm also doubtful on the SD40-2W, although I don't own one to be sure.)  You might be able to fit it in with some significant frame milling in the top middle area where the new board is wider, but the contact spacing may also be a little off.

Future releases, my guess is the new decoder will probably be compatible.   They announced tunnel motors with sound way back, presumably they are working on a new frame for the new decoder.  That's an assumption though. 

[reinhardtjh]

I may have missed this, but will this decoder be drop fit into IM's N scale tunnel motors & SD40-2W, same chassis is it not more or less?

David

That was the plan.  IM delayed the SD40-2, SD40-2W and SD45-2T's until this decoder was finished so they would have a single decoder type to install.

[RAILCAT]

Any further news in discovering the keep-alive connections.

[jdcolombo]

Any further news in discovering the keep-alive connections.

Peteski is working on it. 

John C.

[peteski]

The components on this decoder are so small and so close together that I ended up ordering needle-type probes for my meter to be able to get to the solder pads. Those are on the way to me.

[jdcolombo]

needle-type probes

That sounds vaguely . . . X-Files-ish . . . 

John C.

[peteski]

That sounds vaguely . . . X-Files-ish . . . 

John C.

I can't comment on that. 

[AKNscale]

Any headway Peteski? I'll probably call ESU Monday to see if they've even recieved the schematic yet.

[peteski]

Any headway Peteski? I'll probably call ESU Monday to see if they've even recieved the schematic yet.

I have, but now I have to document it so it makes sense to everybody, and other projects keep getting in the way.  The design is a bit different than a generic decoder. 

[AKNscale]

Ah, I was almost considering wiring it to the U+ and AUX4 then setting AUX4 to always on in function mapping. Don't know if it would work but it was the only thought I could come up with. But I'm pretty sure it wouldn't work as my Select Micros use a separate pad for the cap negative.

[peteski]

Ah, I was almost considering wiring it to the U+ and AUX4 then setting AUX4 to always on in function mapping. Don't know if it would work but it was the only thought I could come up with. But I'm pretty sure it wouldn't work as my Select Micros use a separate pad for the cap negative.

Nope, that is not the way to go (for several reasons).  Give me some more time.

[carlso]

I have a quick question for you. Wasn't the SP a large purchaser of SD-40-2's ? I have not seen any SP shells from IM, have I missed some posting ?

Carl