I’m looking for any new information on the HO Spectrum 2-6-6-2 like the one I’ve had so much trouble with.
For those that don’t remember or didn’t read my original posts about the loco in question. It was a Bachmann spectrum with DCC and sound, factory equipped.
Top speed was attained at step 19 (NCE Powercab) and would not increase with additional throttle. All CVs were changed with several combinations. NO joy!
The other problem was it would jerk going down grade at slow speed. I noted that there was considerable slop in the drive train.
I sent the loco back to Bachmann and they did send me a new one. Same problems. It was clear that they had no clue how to fix it.
I called Soundtraxx and they told me it was Bachmann’s problem. I got the impression that they made the decoder to Bachmann’s specs.
Question: has anyone had these problems and replaced the decoder, with good results?
I would rather not replace the decoder if there is no improvement.
Since your last posts on this subject, I have had the opertunity to purchase one of the new H4 versions of the 2-6-6-2 and to operate another one belonging to a friend. Both still have their dual mode non sound decoders at this point. Both operated fine on DC with a full and complete speed range and no surge or jerkyness on grades. Both have similar play in the driveline as their H5 consins (It is of course the same driveline).
So that brings a total of 4 on my layout, and 5 or 6 belonging to others I know that all lack sound and run fine on DC or DCC. I do know one person who just purchased on with sound, I will ask him for a report on its performance.
But the evidence is getting even stronger that this is purely a sound decoder issue. I suspect the back-EMF, or its settings, is not compatible with the motor/driveline. This could explain both problems.
Soundtraxx can say whatever they want, the fact the locos as a group run fine without decoders, run fine with non sound decoders, and run fine with aftermarket decoders, points directly to that decoder. That is not to say the decoder is “defective” but rather it just may not be suitable for that motor/loco.
Oh yes, I was on the Bachmann forum, no help back then.
Soundtraxx did say the decoder was not suppose to operate the way it does. [|(]
I will try the CVs listed, I like the little engine, but for what it cost I feel I got ripped off.
I’m in the process of adding 40 sqr. feet to the lay out and need a brake from that anyway.
Have a good day.
So do they still have the RF supression capacitors still in them, Sheldon? You’ve said before most decoders don’t like seeing the PWM from your Aristo system, which makes sense - but it sounds like these last two work just fine without pulling the decoder? I’m wondering if the non-sound (but DCC) ones work fine on DCC because the el-cheapo Bachmann dual-mode decoders have neither BEMF nor high frequency PWM drives. Tsunamis have both. It’s not to hard to think that not only would the caps interfere with the high frequency drive but the caps and/or chokes could interfere with the BEMF as well. Non-BEMF high frequency decoders seem to do fine with the caps clipped and the chokes left alone - that would be easy to test by disabling the BEMF in the Tsunami and clipping the caps. If it runs smooth now - try re-enabling BEMF. If it suddenly gets jerky again - that migth be the problem. Remove the chokes and replace with short jumper wires.
I agree with you on this, the non sound decoders used by Bachmann do run OK on the Train Engineer, but, slow speed does improve after they are removed and the capacitors are removed. Also, depending on the loco, the lighting circuits do not always like the combination of the factory decoder and the Train Engineer. I would assume the new H4 does have the capacitors, but I have not been in the tender yet to remove the decoder.
If I recall, Lee has already removed the capacitors in his loco with no improvement. I suspect that the decoder simply does not like motors electrical profile or the Bachmann circuit board, or both.
I have a friend with a sound equiped 2-8-0, it runs great. I have run it, he uses Digitrax. For some yet to be explained reason, each Bachmann loco seems to have a slighly unique lighting circuit control board. I have not been into a sound loco, but this is definately the case with the non sound locos, both DC and DCC, going all the way back to the begining of the Spectrum line.
I understand Lee’s frustration, but I would be very tempted to remove any “extra” circuits from Bachmann and hard wire the decoder or replace the decoder and again, remove the Bachmann lighting board and hard wire the new decoder.
I really appreciate you taking the time to post the list of CVs for me . I have installed and double checked all my CVs. I did notice that there are about six CVs that Decoder Pro does not pull up and show. I did set them with my Power Cab. Might this factory decoder be slightly different than yours?
First off I have not had time to run speed trials yet but it does seem to have a different throttle response. Maybe better.
Now, I do get some strange sounds. Start forward step one I get two whistles and bells. In reverse different whistles and bells.
Speed changes gets me short and long whistles and more bells.
Is this the way it’s suppose to work?
Slow motion down grade is the same with a forward jerking motion. I really don’t expect any improvement is this. There is just to much slop in the drive train. I can see were with DC there is a steady power applied to the motor so it might run a little faster but at a steady pace.
If I can just remember that this is a hobby and should be a fun learning experience. [:-^]
We may have something here. If my measurements are accurate I’m getting 33.9 scale mph at full throttle and 26.36 at step 19. This should be a proportional increase to throttle input. [:D]
I’m going to save these CVs and see how they differ from the charts, and why doesn’t Decoder Pro pick up all the CVS in this decoder?
What decoder does it identify as? A regular Tsunami or s special Bachmann version? Check on the JMRI group on Yahoo and see if there might not be an updated decoder definition to better support th Bachmann versions.
Today I got into the tender on the new H4, removed the decoder, and yes they do stil have a capacitor across the motor - its gone now too. While performance was OK with the decoder, slow speed is better now without it or the cap.
Interesting side note, while the new H4 2-6-6-2 ran fine on the Train Engineer with the decoder, the same decoder, installed in the 2-8-4’s which I am converting to heavy mikes, does not work so well. The locos run fine, but not on trackage with my detectors, I can’t reverse the loco, it just sits there. On trackage without detectors, isolated from my “keep alive” circuit the locos run fine but the lights don’t work. After the decoders are removed and the jumpers installed, everything works fine.
So some of the “problems” must be in the way the decoder and the lighting board interface. And it is obvious that the lighting board in the 2-8-4 is different from the one in the 2-6-6-2. In fact, from wheel arrangement to wheel arrangement, no two Bachmann lighting boards are the same.
I still think the problem Lee is having would be solved by hard wiring the decoder or hard wiring a better decoder.
But what do I know, I’m just hick with a pickup, some guns and some trains.
Hey Guys
Randy
D. Pro does identify the decoder as Bachmann OE
Sheldon
I used River Eagles cv numbers for my loco and it runs as it should, (I think.)
Now it’s just a matter of finding out if I’m too dumb to operate the devices or the manufactures are just winging when they write the manuals.
Although I’m not sure I would buy another articulated because the drive train just has too much slop to run well on DCC. I am talking with the guys on Bachmanns’ web site and over at JMRI’s to see if the proper specs are available. I ask if The regular Tsunami manual covers the Bachmann OE version.
Thanks to all you guys the little locos not too bad now.
Lee
Oh yes, I’ve had the tender apart and clipped out the capacitor but I tried to get the other locos’ boiler apart with no luck. It looks like the only way I could get it apart is with a rock.
Lee, I don’t buy that for a minute, the slop in the driveline has nothing to do with any of this in my opinion. Why would that effect DCC operation and not DC operation?
I do believe Bachmann may not really have the best combination of motor, lighting circuit board and sound decoder for best performance.
Bachmann is working to hit a price point, I don’t know what you paid, but I hope is was not more than about $300. That is street price for a 2-6-6-2 with sound and is way less than any of the other brands for an articulated loco with sound. Just like their “basic” decoder is just that, basic, I suspect the sound decoder is low budget as well.
Before Bachmann offered sound, everyone I knew who was putting sound in them, and many who were just adding DCC without sound, recommended removing all the Bachmann electronics and hard wiring the decoders - still likely to be the best bet with any of their locos.
And again, I will repeat, my four, and several others I have seen all run fine on DC, so the problem is not mechanical, nor is it the motor. That leaves the decoder and the thier lighting board (or as I have suggested many times now, an interface problem between the two).
I saw your post on the Bachmann board today. The H4 is actually a new and slightly different loco from the one you have (yours is an H5). It is the same drive, but has a different tender and that tender has a new lighting board. So results from those who have sound versions of the new H4 may have little bearing on your problem.
If you decide you don’t want it, put it on Ebay, they go pretty well on there.
I’ve had several of them apart, there are no capacitors in the loco, everything is in the tender.
The middle dome comes off, there is one screw, the cab un-snaps and the boiler lifts right off - but getting the dome off can be tricky and getting to the motor requires unwiring the whole loco, a pretty big job after the boiler is off.
Hey, I can be wrong but here is my way of thinking. On DC the power / voltage is applied to the rails / motor, the loco rolls forward and if the cars start pushing the loco nothing changes the same voltage is still applied. The train continues ahead maybe a little faster but not noticeable.
With DCC the throttle tells the loco to accelerate to step 10 when the train starts pushing the loco, the decoder backs off, then it’s too slow, the decoder adds power and surges forward etc.etc. Surge slow, surge slow. The slop in gearing doesn’t allow the decoder instant feed back it goes from slack one way to slack the other way.
It could be the decoder but I’m not spending another $100 until I explore all other options. This old retiree has to squeeze ever $. This is the best I can explain my thinking.
BEMF can do that, a decoder without BEMF or witht he BEMF turned off will work just as DC does, some voltage will be applied to the motor for each speed step and the motor will speed up or slow down as the load changes. BEMMF, especially if set to be too aggressive, will attempt to keep the motor turning at a set speed, however it will always slightly lag any binding in the drivetrain, making for some interesting surges. Same thing happens when you consist two locos with BEMF, they can fight one another and buck and surge.
Not sure what the CVs might be for the Bachmann version Tsunami, but you could try totally disabling BEMF and see if it runs any better. But the only real way to fix slop int he drivetrain is to install thrust washers so the worm can’t keep moving fore and aft. Same problem shows up on Athearn and P2K locos too.
And this is why I like TCS decoders, the BEMF fades out above a certain speed step, that way you get the benefits for slow speed running but at higher speeds there’s no ‘cruise control’ effect and you need to add more juice to haul a train up a hill without slowing and cut back when going down.
Randy, all good thoughts here and you, me and David are all in agreement, but having had several of these locos completely apart, I can tell you (and Lee) that the slop is ot in the worm gears and wold not be easily removed/lessened. The slop is in the drive shaft universals and in the gear towers themselves.
As you and David explain more about decoder programing, I am more convenced its the decoders basic design (or lack of it).