Intermountain SD40-2

[jdcolombo]

I don't see a negative anywhere....

Thanks for the photos!

Well, the lack of a marked negative pad sort of sucks.  There are some caps that might be keep-alive caps on the top side of the board in the middle toward the bottom of the photo (the four caps sitting around the left-hand "neck" are probably the bridge rectifier caps, but then there are three oriented N/S more toward the middle that might be for keep-alive purposes).

I wonder if any of those round gold "pads" on the back side of the board would be a negative . . . ESU doesn't always mark it's negative connections - for example, it's not marked on the Select Micro; you have to figure it out from their keep-alive wiring diagrams.

Guess I'll have to ask Mark Hermann.  It would be nice if ESU would release some sort of wiring diagram for this decoder, but since they haven't updated their LokSound manual in five years, I'm not going to hold my breath . . .

John C.

EDIT:  A closer look at the top side of the board shows that there are what appear to be two solder pads to the left the two dark yellow caps at the  middle-bottom of the photo.  I suspect those two caps are keep-alive caps, and now I'm wondering if those pads might be for additional keep alive connections.   Unfortunately, there is no way to know without some documentation from ESU - but they certainly look suspicious . . .

[Santa Fe Guy]

John.
Several of us here down under are waiting for the narrower Decoder from ESU. Mat told me via email late last year that they were waiting to complete the order for IM before the generic narrow version would be available sometime early this year.
This should solve a lot of installation issues for the older locos where the interior of the body shell had to be widened by careful filling to fit a loksound.
We cannot wait.
Rod.

[jdcolombo]

John.
Several of us here down under are waiting for the narrower Decoder from ESU. Mat told me via email late last year that they were waiting to complete the order for IM before the generic narrow version would be available sometime early this year.
This should solve a lot of installation issues for the older locos where the interior of the body shell had to be widened by careful filling to fit a loksound.
We cannot wait.
Rod.

Agree - I can't wait, either.  When I saw Matt at the National Train Show in Indy this past July, he was very confident that the generic board would be out in November.  I laughed and said "what year," but he insisted that it was going to happen.  I know ESU is working on it, and we'll get it sooner or later.  I've been holding off on any more narrow-hood diesel installations until that happens (instead, I've been converting all my steam locos over to LokSound, and been playing around with PA-1's from Kato, LifeLike, and BLI).

I do hope, however, that the generic board has connections for keep-alive.  I have no use for an SD40-2 given my 1950's NKP layout, but I might buy one just to play around with the decoder and see what might be possible.  I've got to believe there's a connection on that board somewhere for an external keep-alive; we just need to find it.  I'm also curious about the lighting and auxiliary outputs.  The board in the photos has LEDs on both the top and bottom; I'm assuming that the bottom LED on the front of the board is for the ditch lights (non-alternating).  OK - so is that on a different function output than Aux3 and Aux4 available on the board?  In other words, is this a 4-function board or a 6-function board?  If it's a six-function, then those that model the modern era can do all sorts of lighting stuff - headlight, rear light, alternating ditch lights, separate class/marker lights, beacon, etc.  That would be . . . very interesting.  The HO-scale LokSound Select is a 6-function board, so maybe . . .

John C.

[basementcalling]

,

If the wheels bother you, change 'em.  As I pointed out earlier in this thread, here's a before and after on an IM SD45-2, which use the same Atlas trucks:

Before: IM wheelsets. "Ew!":



After: Kato wheelsets:



I also replaced the wheels on two Atlas SD50s.  To me, that solves one problem of the new IM SD40-2.

DFF

My old eyes are missing the difference. Any chance you can reflect and reflect some light in there?

[mu26aeh]

My old eyes are missing the difference. Any chance you can reflect and reflect some light in there?

Look at the face of the wheel, easiest to look at the middle axle of the truck in top picture vs any of the wheels in the bottom picture.

[peteski]

Thanks for the photos!

Well, the lack of a marked negative pad sort of sucks.  There are some caps that might be keep-alive caps on the top side of the board in the middle toward the bottom of the photo (the four caps sitting around the left-hand "neck" are probably the bridge rectifier caps, but then there are three oriented N/S more toward the middle that might be for keep-alive purposes).

If someone is willing to send the decoder to me to borrow it for some reverse engineering (without damaging anything) I'll figure out where the additional keep-alive caps can be attached.
 

[AKNscale]

Is there an instruction sheet with these?

[Mark5]

@davefoxx  - You should send the before/after pic to Paul and company at Atlas.

[mu26aeh]

Is there an instruction sheet with these?

Yes, there is instructions from ESU on default/ranges for CV's and the different sounds etc.

[mu26aeh]

Has anyone heard anything regarding the decoder (no-sound versions ) only models ?

[jdcolombo]

If someone is willing to send the decoder to me to borrow it for some reverse engineering (without damaging anything) I'll figure out where the additional keep-alive caps can be attached.
 

As Peteski notes (implies?), there's always a way to attach keep-alive to a decoder.  All you have to do is find the bridge rectifier, and then solder the negative cap lead to the negative side of the rectifier circuit (and the positive lead to the common positive, which is easy on this decoder since that's the U+ pad on the back).  On some decoders, the rectifier circuit is four individual diodes; on others, there is a single SMD rectifier "chip."  Now that I look at the board again, that thing at the top of the middle of the top of the board with "6RB" (?) on it looks suspiciously like a rectifier, with a bandpass diode next to it. 

The problem is that it's not always easy (!) to solder a wire to the appropriate place.  But it almost certainly CAN be done - you just have to find the right place . . .  It would be very disappointing, however, if ESU didn't provide a pad for the negative connection, like they do on every other LokSound decoder.

John C.

[peteski]

As Peteski notes (implies?), there's always a way to attach keep-alive to a decoder.  All you have to do is find the bridge rectifier, and then solder the negative cap lead to the negative side of the rectifier circuit (and the positive lead to the common positive, which is easy on this decoder since that's the U+ pad on the back).  On some decoders, the rectifier circuit is four individual diodes; on others, there is a single SMD rectifier "chip."  Now that I look at the board again, that thing at the top of the middle of the top of the board with "6RB" (?) on it looks suspiciously like a rectifier, with a bandpass diode next to it. 

The problem is that it's not always easy (!) to solder a wire to the appropriate place.  But it almost certainly CAN be done - you just have to find the right place . . .  It would be very disappointing, however, if ESU didn't provide a pad for the negative connection, like they do on every other LokSound decoder.

John C.

Well, that is why I once I figured out the component locations, I would trace the circuit to find some easy to solder locations for the negative/ground.
Looking at that blurry photo (and without being able to examine the circuit closely) here is my speculation as to what things are.

[ Guests cannot view attachments ]

[nkalanaga]

As for "sensitive to dirty track", my DC locos were as well, until I cleaned the wheels.  I suspect that whatever they used to blacken them, or possibly some oil on them, was the problem.  They ran fine after cleaning.

[SkipGear]

As for "sensitive to dirty track", my DC locos were as well, until I cleaned the wheels.  I suspect that whatever they used to blacken them, or possibly some oil on them, was the problem.  They ran fine after cleaning.

Agreed, mine took a few laps around my son's little 3x3 layout before it stopped stalling randomly. Once the wheels got a good run in, it will crawl around the layout with no stalls at all.

[jdcolombo]

Well, that is why I once I figured out the component locations, I would trace the circuit to find some easy to solder locations for the negative/ground.
Looking at that blurry photo (and without being able to examine the circuit closely) here is my speculation as to what things are.

(Attachment Link)

Yeah, I think you're right - that's probably a choke coil.  I still think those two dark yellow caps are probably for a keep-alive, and now we seem to be getting more reports that once the wheels are clean, drop-outs pretty much disappear.  I remember that Matt Hermann told me at the National Train Show in Indy that there WAS some keep alive on-board.  I'll bet those two caps are it (and maybe the third cap on the right of the two as well), and that would also explain why there was no obvious connection for an external keep alive.

Well, my curiosity got the best of me.  I ordered one of the Iowa, Chicago & Eastern ones so I could take a close look at the board myself. 

Sigh . . .

John C.

PS - I also posted a set of questions about the board to the Yahoo LokSound list.  I'll let folks know if Matt gives me some answers, including confirming that the Aux3 and Aux4 pads will work for additional lighting; why there seems to be an LED on the bottom back of the board (I don't think there are rear ditch lights, are there?), whether there is keep-alive on the board itself, and whether there are pads to add external keep alive.