Calling all Bachmann S-4 owners

[Catt]

Since the decoders are dual mode it seems to me that running the loco on DC should give a clue as to whether it is electronics or gearing that accounts for the nice low speeds.

[SkipGear]

Since the decoders are dual mode it seems to me that running the loco on DC should give a clue as to whether it is electronics or gearing that accounts for the nice low speeds.

Not really because the decoder could have voltage output limits built in to protect the motor. These would be in effect in both DC and DCC since either way, the signal must go through the decoder before powering the motor.

Because of the micro coreless in the 4-6-0, many thought this was the case, but when you pull the decoder, no change in max speed happens. The one thing is that you will find is much better slow speed control with the decoder than without, once you get rid of the overly high Vmin setting they come with. The decoder is a high frequency pulse controler which will make these thing crawl a tie at a time in DC or DCC.

[peteski]

Has anybody (Spook?)  taken this model apart yet?  I'm specifically interested in the motor: How large? Coreless?

[SkipGear]

Has anybody (Spook?)  taken this model apart yet?  I'm specifically interested in the motor: How large? Coreless?

http://www.spookshow.net/loco/bachs4.html

[spookshow]

Has anybody (Spook?)  taken this model apart yet?  I'm specifically interested in the motor: How large? Coreless?

Pete, if I had to guess I'd say it's similar to the coreless motors Bachmann used in their 4-6-0 and 2-6-0 steamers (just with two driveshafts instead of one). That's just a guess, though - I didn't tear mine apart in order to prove that theory 

Cheers,
-Mark

[peteski]

Pete, if I had to guess I'd say it's similar to the coreless motors Bachmann used in their 4-6-0 and 2-6-0 steamers (just with two driveshafts instead of one). That's just a guess, though - I didn't tear mine apart in order to prove that theory 

Cheers,
-Mark

Thanks Mark!

[Scott Lupia]

Guys, I was wondering if anybody has any kind of comprehensive list of the CV's for the decoder in this engine?  I saw that very basic list on the Bachmann website for a similar decoder but can't find anything that relates directly to this decoder.  The reason I ask is that when operating on DCC my engine buzzes like crazy.  Doesn't do this on DC power.  I have had similar issues with other engines that I was able to fix by altering the motor control CV's.  I find it irritating and perplexing that this information is not published on one of the many pieces of paper that is included with the engine in the box.  I was hoping I could find it on the website too.  No luck.  Maybe I just am missing it and am complaining over nothing.  Am I missing something?

Scott Lupia

[spookshow]

AFAIK, the CV's listed in this document are the only ones supported by that decoder (there aren't very many) -

http://www.bachmanntrains.com/home-usa/ez_content/1_Amp_Decoder_Instr.pdf

-Mark

[Scott Lupia]

Wow does that suck!  Thanks for the heads up on that.  I will stop trying to work with it.

Scott Lupia

[C855B]

Aha! That's the doc for the "2-function decoder". From what I could tell in my JMRI experimenting, this appears to be a new "4-function decoder". Apparently JMRI is aware of this, but the official B-mann documentation channel is not. The extra CVs I found in testing definitely took (and regurgitated) values. The question is whether they do anything in this particular model.

Work is going crazy this week, so I cannot promise specific test time. I will try to steal a few moments tonight or tomorrow to put together a test loop and see if the motor curves do something.

[spookshow]

Boy, Bachmann got the parts schematic for the S-4 up on their website right quick. But apparently not for the decoder (if it really is new/different)?

-Mark

[C855B]

I just spent an hour with it on a loop on the dining room table. Sadly... it is in fact the 2-function decoder. So you know what it is already. Messing with speed table values did absolutely nothing, as did any changes to the headlight management tables that were specific to the 4-function version.

I find it really odd that all of the "extra" CVs responded normally if you selected the 4-function decoder in JMRI. That has to mean that the DCC system side of firmware support for the 4-func is in the 2-func, just not connected to anything. Or maybe the output code is suppressed. I dunno.

No magic discovered.

[peteski]

I just spent an hour with it on a loop on the dining room table. Sadly... it is in fact the 2-function decoder. So you know what it is already. Messing with speed table values did absolutely nothing, as did any changes to the headlight management tables that were specific to the 4-function version.

I find it really odd that all of the "extra" CVs responded normally if you selected the 4-function decoder in JMRI. That has to mean that the DCC system side of firmware support for the 4-func is in the 2-func, just not connected to anything. Or maybe the output code is suppressed. I dunno.

No magic discovered.

I suspect that what you are seeing it a poorly written firmware on the microcontroller.  Probably some code that was added but not properly cleaned up. I guess that these are very inexpensive decoders. I guess that we get what we paid for. 

[Cajonpassfan]

I know that a four function decoder is better than a two function decoder, no argument there.
But, the S4 is also  the finest running switcher I own with a near perfect power curve and top speed so I don't personally see the need to change anything in the way of performance. The decoder seems very adequate for motor control.

The lights, at least on mine, are either on or off in both directions, which I believe is prototypical for a switcher. F0 turns the lights on and off, F1 dims them in both directions. Certainly the crew would not turn the lights on and off with every reverse move while switching, which is the way other switchers come, cute but wrong. When switching a siding next to an active mainline or parked next to it, the lights would have been dimmed, and F1 allows for that. On mine, the lights also dim somewhat when in trailing mode on F0. In F1, there's no change. Again, good light effects, IMHO, as yard switchers generally did not display classification lights, ditch lights and other "special effects". So it begs the question about why a four function decoder would be preferable for this unit and whether sometimes basic functions are good enough, especially at this price.
Maybe I'm missing something?
Regards, Otto K.

[SkipGear]

I played with one for a couple hours last night also. The CV's are the same as the 2 function decoder.

There is no way to control the amount of dimming between forward and reverse. There is a CV for dimming amount but it only controls the amount of dimming when F1 is pressed.

CV's available: 1, 2, 3, 4, 17, 18, 19, 29, 50, 51, 52

50 is for DC control reaction when on DCC
51 control the buttons used for lighting
52 controls the amount of dimming when F1 is pressed.

That is it. I tried programing some of the other features listed in the 4 function and ended up needing to reset the decoder to get it to operate correctly. The decoder can accept them and read them back but nothing happens.