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Author Topic: my new locomotive hums  (Read 4334 times)
GRZ

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« on: March 16, 2011, 05:11:49 PM »

   I have a 6 week old Bachnann 440 with dcc. I love it,so I spent my next 6 weeks food money and got the one with sound..wow! now that I have one to conpair the first one to. the new one moves away with a bit of power, and no hum.the first one has a loud hum and takes a lot of power to get under way,but runs along good after is under way.any one know the reason?? thank you grz
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Doneldon

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« Reply #1 on: March 16, 2011, 06:55:02 PM »

GRZ-

The low-tech decoders used in Bachmann non-sound DCC locos are known for their hum and crude
low- speed operation. Their operation sometimes improve a bit with breaking in but the hum tends
to be a persistent problem. The only solution is a new decoder (not just a replacement with the OEM decoder).
                           
                                                                          -- D
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richg
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« Reply #2 on: March 16, 2011, 07:17:10 PM »

Usually when a loco hums, it does not know the words.  Smiley

Remove the stock decoder and get the below decoder. Plugs right in. I use the decoder and it is very nice.

http://www.digitrax.com/prd_mobdec_dz125ps.php

Rich
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #3 on: March 17, 2011, 12:25:31 AM »

If your DCC system will let you program CV's, you will find that the BEMF control in the decoder Rich recommended will start your old locomotive as smoothly and precisely as your new one.  The Tsunami decoder in you new one has a top notch motor control section with BEMF as well as a superb sound section.  The only down side to BEMF control is that you may have to turn it off to keep the two locomotives from fighting with one another if you want to double head them.

If your DCC system does not permit programming CV's, you will still find that the silent drive of the recommended decoder lives up to its name.

Although Rich did not mention it, you may have to snip out a capacitor or two to allow your old locomotive to work properly with this or any other silent drive or supersonic decoder.  Directions are available on this site or on the Digitrax site.  Or just ask.

Jim

p.s. teaching your old locomotive the words may not help - locomotives usually sing in an off-key monotone.
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Growing older is mandatory but growing up is optional.
GRZ

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« Reply #4 on: March 17, 2011, 08:57:22 AM »

 thank you for your help, I have no idea how to work on this new system. I have the Bachmann dcc control, how do I tell if I can change the cvs withthis unit? also what would the new decoder cost? like i said fixed income is a big factor. should I send it back to have this done? it would be nice to have it work like the newer one. Greg
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jward


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« Reply #5 on: March 17, 2011, 09:07:26 AM »


p.s. teaching your old locomotive the words may not help - locomotives usually sing in an off-key monotone.

locomotives come in all different tones though. and some sing quite well.....i live halfway up a 1% grade, and i hear them singing all the time. give me a dream consist of sd35-sd45-gp9 and u25b and you'll hear a 4 part harmony.......
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Jeffery S Ward Sr
Pittsburgh, PA
GRZ

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« Reply #6 on: March 17, 2011, 11:23:52 AM »

Jim, this locomotive has but two pistons, and they live below d valves one each side of the BOILER..and this loco burns coal a renewable re souse..[if you live long enough that is ] I drove gas tanker for gulf oil 30 odd years and sat beside in back and on top of diesel engines and to this day I miss the sounds BUT!!! steam is my thing..thank you for your comment GRZ.
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Johnson Bar Jeff

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« Reply #7 on: March 17, 2011, 01:45:55 PM »

Usually when a loco hums, it does not know the words.  Smiley

As soon as I saw the title of this thread, I wondered how long it would take/how many posts it would take for someone to come up with this line.

It didn't take long at all. ...  Grin
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Doneldon

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« Reply #8 on: March 17, 2011, 02:35:05 PM »

GRZ-

I found three questions or implied questions in your 7:00 am post.

Whether you can change CVs depends on which Bachmann system you have. If it's Dynamis you can; if it's EZ DCC, you can't. Well, that's not strictly true. You can program loco numbers and which way is forward with the EZ DCC system but that's so elementary in my book that I don't really consider it programming.

A decent new decoder should cost less than $20 unless you also add sound. With sound you are going to be closer to $100, depending on where you get it, whether it's on sale, etc. These costs are for the decoder only; installation will cost quite a bit more, especially for sound. Figure $25 or so for non-sound and $50 give or take for sound (prices in my area, the Twin Cities). Be sure to add shipping costs if you must send the loco out for the work. Your LHS can probably refer you to a local who will at least save the postage. OR, do the work yourself. It's not a difficult job for silent decoders, usually, and there's lots of help on this board and elsewhere on the web.

I hate to throw a t**d in the punchbowl, but be aware that your older loco will never be a new one so it may never operate like a new one. Even if you install a quality decoder you'll still have an older motor and mechanism.

Whatever you do, be sure to have fun!
                                                                       -- D
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GRZ

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« Reply #9 on: March 17, 2011, 05:57:09 PM »

 hi there mr Doneidon.. thank you for your reply..yes my dcc controk is the ez comand type.the engine is new,last of jan o11 / it sounds to me like the hum/growl is the motor. the growl begins when the power is turned up, one or two nochs keep turning up the power the sound gets louder loco is not moving more power till the white line on the  k nob gets just before 1/2 the engine starts to move the sound seems to go away the loco runs smothe . the other engine all it takes is very slight throttle and off it goes. ive held the little guy bottoms up and moved his wheels they move free, I dont think there is binding any where.I guess I should call Bachmann and ask them what I should do I shure dont want to spoil this thing ive waited too long to get them. yes im haveing fun.  3rd childhood...grz
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Doneldon

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« Reply #10 on: March 17, 2011, 06:29:31 PM »

GRZ-

It's just Doneldon, not Mr. That's my real first name, not an affectation.

As for your noisy loco, it sounds like you might be a good candidate for a new decoder. First, though, see if removing the decoder and installing the dummy plugs improves operation. You can find an exploded view of your tender here:
                               http://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_440_DCC-tender.pdf
This should help you see how to do it.

For your slow-to-respond sound loco, well, sound systems do use quite a bit of current which reduces what's available for the motor. Perhaps you can find a friend or a nearby railroad club where somebody will program your loco so it starts sooner in the range of your throttle.
                                                                            -- D
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #11 on: March 17, 2011, 09:34:21 PM »

GRZ, about 9 or 10 posts above, Rich recommended a particular replacement decoder, a Digitrax DZ125.  This little marvel will solve both your problems, assuming your older 0-4-0 is otherwise running well.

The first problem - the hum - is caused by the relatively long and slow pulses of electricity that the Bachmann decoder feeds the motor.  They make the motor vibrate.  Bachmann uses a decoder with long, slow pulses so that they can filter the output of the decoder to prevent radio and TV interference.  They do this so that they can sell their locomotives around the world, even in places that have strict limits on how much radio and TV interference can be generated by electrical devices.  In North America, our limits on radio and TV interference are not so strict.  So we can remove these filters.  Once we do that, we can use decoders that produce short, fast pulses of electricity to run our locomotive motors.  These pulses can be so short and fast that they just do not have time to vibrate the motor.  And even if they did, it would vibrate too fast for us humans to hear.  The decoder Rich recommended is a supersonic, silent type so it does not rattle your motor.  Therefore it will produce no hum.

The second problem - the late starting - is caused by the motor needing about 1/4 of maximum power just to get started.  It has to overcome the friction of the gears, the side rods, the motor itself, and the friction of the wheels in all the cars behind the locomotive before it can start to turn.  Many decoders allow you to adjust the starting voltage.  This is the voltage applied to the motor when you turn the speed control just past the stop position.  This system works reasonably well.  It would work perfectly if the total friction the motor has to overcome was constant.  But the friction changes depending, for example, on how many cars the locomotive is pulling and on how warm the locomotive and the cars are.  A better alternative is to use Back Electromotive Force (BEMF) control.  The permanent magnet motors that drive our locomotives also work as generators.  When we power the motors with pulses of electricity, we can use the time between the pulses to measure how much voltage (electromotive force or EMF) that the motor is sending Back when working as a generator.  This Return Voltage or BEMF tells us how fast the motor is turning.  A decoder with BEMF control compares the BEMF of the motor with a voltage we send the decoder by adjusting our throttle.  If these voltages do not match, the decoder feeds less power or more power to the motor until they do.  We can set up a speed table so that at 1% throttle, our locomotive will travel at 1% of its maximum speed, at 10% throttle, 10% of maximum speed et cetera all the way up to full throttle.  Now when we turn the throttle just a tad past stopped, the locomotive will start moving.  And the BEMF control in the decoder will makes sure it does, at the right speed, no matter what the friction is.  In effect, we have turned our throttle into a speed control instead of a power control so it works more like setting the cruise control on a car to a particular speed instead of working the throttle to change the amount of power we feed to the wheels.

That is the short version of what a better decoder can do for you.  All of this and a bunch more from a $25 decoder.

Bypassing the present decoder by installing the dummy plugs will simply give you a high pitched sizzling sound in place of the hum.  It will not correct the delay in starting.  From your initial post on this thread, I understand you are happy with your sound locomotive.  That being the case, there is no need for anyone to play with the CV's.  The locomotive that needs some changes is your "older" one, if you can call a six week old locomotive "old."  (On my layout, the "older" locomotives are those made before 1980.)

I am sorry to see you live so far away from Saskatchewan.  Here in Saskatoon, the group I model with has a standing offer on installing decoders - bring along two locomotives and two decoders and one of us will install the first decoder for you while you look over his shoulder.  Then you install the second decoder while he looks over your shoulder.  After finding how easy they are to install, you never have to worry about installation cost again.  I hope you can find a club or a group with a similar offer in your area.

Jim
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Growing older is mandatory but growing up is optional.
Joe323

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« Reply #12 on: March 18, 2011, 10:13:32 AM »

I have a question related to this topic, so I'll ask it now.  I have heard of these so called silent running decorders and that they eliminate noises that humans can hear BUT  dogs can and that the noise might disturb our dog.  Any truth to this?
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GRZ

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« Reply #13 on: March 18, 2011, 11:45:37 AM »

DEAR JIM, wow I understand your anser to the problem I think? I called BACHMANN in PIHILY, the lady told me to re prograham the loco,using the information on the dvd that came with the loco. I did this and it helped a little ,she said I may have to do this 2 or 3 times, not too close together tho,im too old to know how to work this new stuff,I have no one that can help in my area ,im the first to make this dcc move in my area, the hobby shop in W.LEB N.H.is more interested in plaines and gas powerd cars. they wont evan order rail road stuff for me, I have to mail order every thing, boy how I wish we lived closer you have the knowledge to work this stuff. will this vibrating hurt the motor ?thank you ever so much for your help grz
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OldTimer


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« Reply #14 on: March 18, 2011, 12:22:53 PM »

Neither my dogs nor cats pay any attention to my layout.  Engines are mostly equipped with Digitrax quiet-running ("SuperSonic") decoders.
OldTimer
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Just workin' on the railroad.
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