Can't identify DCC Sound Decoder on Bachmann 2-8-0

Model Railroader Electronics and DCC
1

New to this, go easy on me… :wink:

A friend sent me a Bachmann 2-8-0 and two tenders. One was an SP Vandy tender with a DCC and sound card in it. When I operated the loco + tender on DCC you could hear the motor spinning (turns out the nylon gear on the motor was cracked) and I could get bell, whistle, and hear steam chuff.

I had to get some parts and redo the loco. While I waited for parts I moved the DCC/sound, plugs, etc into the other tender, a coal type tender.

Then I screwed up. I put it on the program track, read the decoder, picked something, set a new long address, then went to the sound volume tab and turned it up to full volume, and then saved every page out to the loco. Pretty much wrote over the top of anyting that was there. The loco will run, but no chuff/bell/whistle. F2, F3, etc. can produce coupler clank, pop-off (?), some other sounds.

I Googled the heck of it… I tried all of the Soundtraxx Bachman OEM and Bachmann Sound Value options under the Soundtraxx folder. The loco runs on all options, and I can get accessory sounds on some of the function keys, but never chuff, bell, or whistle. I have checked on all those option under the sound tabs in Decoder Pro and there are options for all of those listed.

By the way, when I use DecoderPro to try to read the Decoder (CV8, etc.) I get nonsense results and it says it is unidentifiable and there are several options: Athearn diesels, BLI diesels, N scale stuff, etc.

Looking at the birds nest… there are a lot of heat shrinked solder connections. Maybe this card is an upgrade to the standard Bachmann gear?

It would be great to find the correct DCC/Sound decoder profile for this card!

Thanks,

-Richard

2

I have not seen a sound decoder with a IC has large has shown, when you read CV 8- what do you read back?

have you tried a decoder reset?

3

If those shrink wrapped connections (and the decoder being wrapped in blue painter’s tape) aren’t your doing - that is an aftermarket upgrade installed by a previous owner.

Post a picture of the other cide of the decoder - that side just has the power supply parts. The fast that it has a big giant voltage regulator (the 3 legged part in the middle) makes me suspect that on the other side you will see a big blob of epoxy rather than a neat square or rectangular main chip and this is an MRC decoder (the cheap Chinese capacitors also lead me in that direction).

–Randy

4

Some of the heat shrink is mine… as is the blue tape while I wait for a larger piece of shrink wrap to show up so I can cover it. It had a shiny black plastic heat shrink wrapper on it, I cut that off looking for clues as to the board manufacturer. Here’s the back side of the board… and the blob! So maybe this is MRC?

I didn’t realize that decoders can be reset. Back to factory original… and then after that just use DecoderPro to read every page?

Many thanks for the help on this!

5

I’m pretty sure that’s an MRC. Which one though is the question. If you read CV8, what value do you get? 143 is MRC.

Some MRC decoders reset if you program CV125 to 1.

SO far, going one by one through the steam HO decoder manuals, the 01630 is the closest in appearance. Most CVs are the saem across all MRC decoders though. Using the wrong definition, you probably set all the sound levels to 0 or invalid values, so all you get is silence. Even the reset may not reset that - as the instruction sheet says it only resets the short address to 3, clears momentum and any star/max voltage. But the instruction sheet does list the sound volume CVs and the default values so you can set them yourself.

Look carefully along the edges of the decoder, maybe the model number is printed on it. MRC decoders are in the format like 0130, 01629, etc. a 0 and 4 digits. It would be on the green PCB itself, not the value of any of the components.

–Randy

6

Actually, can’t be a 1630, the 1630 has wires, yours has a 9 pin connector. Could be the 1869, but the picture shows the blob in a diffrent layout. Maybe an 1819.

All the instruction sheets are here: https://www.modelrectifier.com/Articles.asp?ID=254

Also, you can read CV7 as well - a value of 32 seems ot be the older decoders, a value of 19 are the newer ones.

–Randy

7

Randy, thank you for the very specific information. So helpful, and I appreciate it! I will give this a go tonight after work and see what I can figure out based on the info you provided. I will report back…!

8

Randy, definitely 143 MRC, but CV7 = 31. I tried all of the profiles in JMRI Decoder Pro. I don’t know if this is valid way to proceed but I would Add New Loco, select the MRC profile, the open the programmer and write all pages. (Does it matter if I am programming in Direct or Paged mode?) Then I would try the loco. Everything fails except Profile 1656. The manual sheet for that one shows it does not have a JST connector, but it’s the only one that (sort of) works. I get chuff, whistle, bell and sounds at idle. However, if I change anything (like the type of whistle) it remaps the function keys… but then I can’t change the function key mapping because that tab is blank in DecoderPro. 1656 isn’t the correct one… but it’s close. Also, tried writing 1 to CV 125 a few times, it definitely resets the address to 3. But when I do that all the sound functions are inoperable. I’m so close! Yet so far… I will take a look at the board next and see if there are any clues there.

9

Don’t write all pages until you have definmitely identified the decoder - thic can be setting some CVs that aren’t in the decoder you actually have, or setting CVs to values that are not supported in this one particular one.

About all you can do is go through the instruction sheets one by one, and see if any of them list CV7 as 31. You can skip the diesel ones, since this is a steam decoder.

–Randy

10

31 isn’t listed on any of them. 32, 19. That’s it. Hmmm…

11

That sounds like you need a programming booster, many sound decoders won’t read correctly without it. I had a similar problem with some decoders before I added a booster; Decoder Pro either wouldn’t pick up anything, or it would pick up obviously wrong stuff. If Decoder Pro misreads the decoder type, all the sheets are going to be wrong, so changing/writing a sheet is going to mess up the decoder.

As Randy said, if there’s heat-shrink inside the tender, someone added the decoder later. A factory installation would either have a sound decoder plugged into the receptacle on the lightboard, or would have a sound decoder in place of the lightboard that would be soldered to the connections on the decoder. They wouldn’t be splicing wires and using shrink wrap.

p.s. if you can figure out what type of decoder is in there and which CV to change to do a re-set, you can change the CV on a programming track even if you can’t get your system read back the CVs.

12

It’s ver definitely an MRC, the problem is, which MRC? Since the second CV that could narrow it down returns a value that according to MRC documentation isn;t any of their decoders. But then again, it is MRC - I did buy one once to try it in an Athearn RS3, and while there is a CV to change horns, they don;t tell you which value for the CV equals what type of horn. WHen I contacted MRC, they told me they don;t keep track of that information. Into the trash it went. It wasn’t a good runner anyway. Luckily I got it well under the MSRP on eBay but really it wasn’t worth the space it took up. But I don’t like to say negative things about a product I’ve never used, so that was my TOFTT moment. Making manuals simple to understand doesn’t mean leaving out important information on how to do things.

Some of their older decoders, they even say they do not support readback, if it reads, consider yourself lucky. My program track setup with my PR3 was able to read some at the club, which was somewhat surprising, but as least I was able to change the volume for the member. The newer one I got for the RS3 didn’t have any readback issues.

If trying to change the horn type CV changes functions instead, that may be another clue, see if any of the decoder manuals use a different CV number for the horn. And don’t write all sheets unless you were able to read all sheets from the decoder, if you get one that mostly works, try just writing the changes you’ve made, not all sheets, that way if there is some other CV that is not correct for the purpose, it won’t get written back to mess up the decoder again.

–Randy

13

Mystery solved, still need advice. It’s a loco genie. The layout is the same as the board in this photo, and includes the tell-tale red antenna wire.

I read the data sheet, it responds to regular DCC as well as the wireless feature of loco genie.

So, the quesiton, there’s no loco genie profile in Decoder Pro for loco genie. Can I just create a new loco in Decoder Pro but not select one from the menu, and then just add the default values show on the table for each CV? And then… how are function keys mapped? Will that automatically happen if all the CVs are correct?

14

No, a decoder profile is a bit more complicated than that. You’ll just have to set the CVs one by one, either using the single CV programmer or just use your throttle. You won’t be able to properly store this as a roster entry and actually be able to make changes without messing it all up again.

And I see in typical MRC fashion the information is confusing and likely not correct - it lists two different CVs for controlling the adaptive BEMF!

–Randy

15

My first sound loco was like that. From Athearn. A Roundhouse 4-4-0 and it was a MRC decoder. Came witha remote. About maybe ten years ago. The red wire was for the wireless remote. Sound I think. Not sure what else.

There is an MRC IO Group that might have the specs. Former Yahoo DCC Group I use to belong to.

I trashed the decoder and remote and put in a SoundTraxx Micro.

From then on I bought the 2-6-0 and 2-8-0 with only non souind decoder and put in Micro’s and a speaker.

Those locos looked terrible next to my Bachmann’s. Very plain.

2-8-0 same lenght as a 4-4-0 but they ran very well. Two stage gear box.

Rich

16

Well at least you can do the factory re-set, set CV125 = 1.

https://www.modelrectifier.com/v/vspfiles/resources/dcc/021500%20Loco%20Genie-Steam.pdf

Based on the data sheet, it looks like the CVs line up pretty much like the other MRC sound decoders, so maybe you could try programming it in Decoder Pro using one of those MRC files. However, you will need the booster I mentioned earlier, you can’t read MRC decoder CVs without one.

FWIW I have a number of engines with MRC sound decoders, and I find them pretty easy to set up. The default settings work out well, I usually just choose the horn and bell from the available ones, adjust some of the sound volumes down a bit, and change the lighting (which is just one CV, very easy). Then I speed match the engine to my “golden engine” using the usual speed and momentum CVs 2-3-4-5. Even without Decoder Pro, it doesn’t take long.

17

Randy, Rich, Stix… it turns out it’s not that version of Loco Genie either. Resetting the decoder using CV125=1 loads values in the default registers that don’t match those shown on the sheet. I also used the PowerCab to load every CV as shown on the table. Loco runs, no sound. So… no joy. Grrr! I can read the CVs with my PowerCab on my small track… not using a booster? Maybe I’m missing something? Thanks!

18

I had the Power Cab at the time but did not think much of the decoder. Neither did a few people at the time which is why I trashed it.

19

I’m not sure the chart is accurate, given the two different CVs for the same thing, plus it shows CV7 as 0, not 31. ANd notice that the CV125-1 reset only sets SOME CVs to default values - the ones marked with a * in the chart, assuming even that is correct. All other CVs - who knows? I’d set them one at a time to the default values listed and start with that.

And if that doesn’t work - I’d get a normal decoder :slight_smile:

–Randy

20

Randy, I finally figured something out. One of those RTFM moments. I realized that “Write Changes on this Sheet” was a precision change versus “Write Everything on this Sheet”. I went back to the 1656 profile, wrote every sheet to the loco, and then just surgically changed certain items like momentum, whistle type, chuff rate. I just saved that change, not the whole sheet. Doing that the loco is running nicely, the sound works, and the function mapping works correctly on my Power Cab. I duplicated the profile so I have this as a baseline if something goes wonky on it again.