Hi Guys [:)]
I have been trying to get Tom at Bachmann to give me the low down on the speed expected from my 2-6-6-2 but he has not gotten back to me yet.
Can anyone with a DCC system (preferably a Power Cab) give me the speed that I should expect from the critter.
I measured mine on a level 4 foot stretch of track, and computed the speed with the on line calculator. I have the (times) in seconds for that test, from step 10 (Power Cab) through step 28. My times step 19 through 28 are all the same. If anyone has the time to check this for me I would sure appreciate the help.
A DC system would not give the same results, I think. [%-)]
If the decoder is bad ill’ return it but I don’t want send it back if it is just a slow loco.
A fellow club member has the non-sound version of this locomotive and they do run slow – actually more prototypical. The real engines had small drivers and were made for heavy drag freights, not passenger service.
Thanks, I have the manual but it doesn’t tell me how fast it should go or why the last 1/3 of throttle does not provide any increase in speed over the track.
You probably need to adjust the default speed curve, but if you only have a Power Cab you can’t do this. You need a system that can connect to a computer so you can use Decoder Pro and let it read the decoder’s current settings, and then look at the default speed curve. I don’t own one of these engines so I have no idea how they are set at the factory.
The Power Cab is too limited to be able to connect it to a computer so you can’t use Decoder Pro with it, but you may be able to find someone who can do it for you.
I have Decoder Pro and everything is set for for straight line acceleration with max CV at 255. Verified by Power Cab CV read out. I just need to know how fast max speed should be, and why speed peaks at step 19. Is this normal? Can someone verify If another 2-6-6-2 works this way.
Page 17 of the decoder user’s manual tells how changes to CV 25 can select different speed curves. Try the different values given in this table of logarithmic curves and see what effect they have on performance.
I’ll ask again - when you reset it, did you try it in 28 or 128 speed steps WITHOUT the speed table to see whatthe true top speed is? If there are 28 discrete values in the speed table and each oen is higher than the one before it, it shoudl not stop changing speed at step 19, as it would not be gettign full voltage to the motor. I still say there is an issue with the way the decoder is handling the speed table. Try it again with NO speed table (and adjust CV29 to suit) and see if your stop speed isn’t more liek what others have reported - and that it moves faster at step 28 then it does at step 19.
There are still some that don’t know just how versatile a Power Cab is. Even though I use Decoder Pro and a laptop it’s so much faster to read and write one or two CVs with the power cab.
The decoder is set for 28/128 and the speed CVs are set correctly with a straight line numbers. I checked this using the Power Cab CV read back capabilities against the owners manual.
What I really need is to know how fast the loco is supposed to go.
As I see it there are two possibilities. one the decoder is bad and two there is so much drag internally that the motor can’t pull it any faster. I would bet on the first.
I’ve never measured how fast my 2-6-6-2 can go so I can’t tell you exactly what it’s top speed should be, But my guess would be maybe a scale 40-50 MPH.
Keep in mind these were big engines with small drivers which created problems counterbalancing the weight, so real USRA 2-6-6-2s were generally restricted to a 20 MPH top speed. It’s not like a later high drivered 4-6-6-4 UP Challenger that’s meant to haul fast freight or passenger trains at top speed, it’s meant to plod along slowly with a long “drag freight”. Mine is generally used on iron ore trains, usually at around 10-12 MPH.
To be honest, I usually only use DecoderPro to look up odd settings - it’s quicker then finind the correct manual and looking it up. Almost ALL of my programming is done directly from the system. It’s just faster. I don;t have multitudes of lights and beacons on any of my locos, and I model a time long before ditch lights, so all I generally ever set is address and start/mid/top. No need to use DecoderPro for that with ANY system.
Sorry if you feel the eed to ignore my suggestion, but you will NEVER find out the true actual top speed if you don;t get rid of that speed table and test it in ‘plain’ mode. There is something wrong with the speed table if it stops changing speed from step 19 to 28. It’s either getting full voltage at step 19, so each succeeding step is no more voltage to the motor, or the voltage it sends to the motor from 19 to 28 is the same. Either way, clearing the speed table will determine that. Using no speed table and making sure start and max CVs are not set (Tsunami does not use the mid voltage CV6). It might be enough to just change CV29 to not use a 28 step speed table but I’d just do a reset, dial up address 3, and crank the throttle wide open.
Randy
I have tested all suggestions and nothing changes. In business, if an employee had a suggestion I always thought it was wise to consider it.
The Tsunami default for speed is a straight line. With V start, or speed table the results are the same. Reset to default nothing changes. The speed is constant from step 18 through 28, this is what causes my concern. Since I have no way to measure the output of the decoder I can only go by top speed. If 29.66mph scale is correct so be it. I just find the flat response strange! [%-)]
OK, you previously mentioned after you reset it you programmed the address and put in a straight line speed table. A straight line speed table (in CVs 68-93, with CV29 set to 50or 54) is NOT the same as “no speed table”. That’s why I suggested removing the speed table and setting CV29 to 34 or 38. Even though having 255 in CV93 should make a speed table that provides maximum voltage to the motor and step 28, and if each previous CV is some lower number there should be a difference ins speed as you move through ALL the steps, that obviously isn’t working. What I’m getting at is to verify the actual top speed this loco moves at is to go back and completely reset the decoder and run it on address 3, and see how fast it goes.
One other thing, since this is a Bachmann, it probably has capacitors across the motor. That seems to work with the cheap Bachmann DCC On-Board decoders since they don;t use a high frequency drive, but with the better quality motor drive of the Tsunami or other quality decoders (and as Sheldon will confirm, the high frequency PWM control from his DC Aristo system), the cause no end to problems as the drive frequency reaches a frequency that the capacitors filter out - in a capacitor that means starts appearing like a short. For best operation these need to be cut off - completely removed. SInce they are in parallel with the motor, they can be cut off and nothing else needs to be done - no jumper wires or anything.
Lee, Randy is right on with this. I would have never thought Bachmann would have put sound in these locos without fixing this problem.
I have never seen inside a Bachmann sound tender - BUT, I suspect that you may be looking at a standard Bachmann lighting board with a sound decoder pluged into it. That is how the DCC only versions are done. If so, the lighting board will be the terminis for the plugs to the loco and the wires from the tender trucks and will have the female side of the eight pin DCC connector. The capacitors are on this board. Two of the wires that go to the four wire plug are the motor leads and they are typically marked M+ and M- where they attach to the board. At that area of the board, there is usualy one or two capacitors, sometimes old fashioned disc type, sometimes modern “chip” type. In the circuit they are simply across the two motor leads - simply remove them.
If this is the problem, they are shorting out the motor output from the decoder and dramaticly distoring the effective voltage to the motor, AND confusing any BEMF or similar motor regulation circuit in the decoder.
Again, as much as I like Bachmann products, I will say if I was using DCC, I would remove all the original Bachmann boards and install hard wired decoders - everyone I know who has done that has been very happy with the results. Either that or they have installed Digitrax or other 8 pin plug in decoders with good results - also removing the capacitors.
And, as Randy said, I remove these capacitors even for DC use. Dispite some disbelief by others, my tests show that even with the most ordinary DC power packs, removing these capacitors improves slow speed, smoothness, and control range of these locos. And on a pulse width modulated DC throttle like the Train Engineer, the results are dramatic. My Spectrum 2-8-0’s creep along as slow as any decoder equiped one and start and run smoo
I just opened the tender (again) what appears to be the audio board is plugged into the other one. I have not pulled the boards yet, just trying to get up the nerve but I don’t see anything that I recognize as a capacitor. In my day a capacitor was tubular with a wire to each end. My next thought was that it might be in the engine.
Oh well this gives me a direction to explore now. [dinner]
Lee, knowing Bachmann, it is not in the loco - a disc capacitor is a small disc or just a blob , usually brown or green, with two leads comming out. If its this type the will be standing up on their leads. They will be small about 1/8" to not more than 1/4" in size.
The more modern circuit board type, which are appearing now on the newer boards, look like surface mount resistors or diodes, but are actually capacitors. Very small little rectangular boxes with tinned ends where they are soldered to the board.
Lee, if you could post a picture of the boards, I might be able to help more.
Understand this, I am reasonably sure the decoder and the sound components are all together and the other board is a lighting and interface board typical of other Bachmann locos.
Again, the interface board will have the connections to the loco plugs and will be where these noise filter capacitors are found.
Here are a couple examples. The first one is from the Spectrum 2-8-0, the second from the 3-truck Shay. Point is, this is what a typical capacitor looks like.
Here’s the image, its about the best I can do without reading the camera instruction. [:-^]
The silver thing under the right hand board is the speaker. OK I traced the red and black wires back from the engine. That would be track power to decoder. That leads to the right hand side of the left board. M+ and M- leads (orange an tan) come from the right hand corner (closest to the camera) of the left board back to the engine. There is a rectangle block about 1/4 by 3/16" soldered directly to the board across the out put, I assume. No leads visible.
My teachers definition of assume. Makes A** out of U and ME
