Slow Bachmann


KB02

KB02

Well-Known Member
One of my engines is a Backmann (not sure of the series) GP40. Great little engine that isn't picky about dirty track at all. It was basically my workhorse engine until I switched everything over to DCC. I put in the NCE BACH-DSL decoder in as it was just a drop in upgrade and the engine slowed down dramatically. With top voltage cranked up to 255, at speed step 28 it only moves at roughly a scale 50 mph. While this is fine for "Scale" operations, it just seems really out of place compared to me other engines.

Would anyone have any suggestions on how to speed up this loco?

1C36AA13-FEE7-4DFA-AFDD-67118D211C5B_zps7faew1pq.jpg
 
I have exactly the same loco and exactly the same problem, this started a couple of weeks back,
I took the loco apart, cleaned everything and oiled it, still no good, so then I changed the decoder,
still the same, I took the motor out and checked the speed on dc, it seemed ok but I thought it should
run a bit faster, I checked the little brushes in the motor and all I could see was the spring on one side,
so I'm guessing I'm needing a new motor, about $20 from Bachmann, a friend got a new motor for me but
it was out of a gp30 and had flywheels on it so no good for my loco, so rather than experiment I'll just trash
the loco as most of the hand rails have had it.
 
The brushes usually have a black carbon end the rubs the commutator, if they've worn out and gone then yes, a power drop will occur. You might be able to get them from Bachmann, if they can be got at.
 
As far as voltage to the motor, I don't know. I have two multi meters, and they both appear to be on the fritz. :mad:

I did some more research and, with what Peroni had to say, it seems like a common problem. I wonder if Bachmann put two different motors in the locos; one for DC and one for DCC? I know the decoder instructions say to remove the resistors, but there were none to remove.

I did some actual speed testing, too, and I was wrong about the 50mph. At top speed, with max voltage cranked, it runs a scale 70 mph. While more than enough for scale operation, it would be nice if it could do 90. I also tried this with a different decoder (didn't think of that earlier until Peroni mentioned it) with the same results.

I also pulled the whole thing apart to look at the brushes. They looked pretty good to me.
CD1044D8-C454-4B6D-B22D-3C6A4CCD4B7E_zpsyktj0qkg.jpg

I don't care for how the springs and brushes are held on place by a thin bent metal tab, but it seems to work.

Maybe a new motor would be the best option if I want to speed it up?
 
Those brushes are fine, plenty of "meat" on them. Maybe binding of the bearings on the shaft. Crandell suggests hooking the motor up to DC wires and throttling up to full voltage, then giving a smart tap to the sides of the motor near the ends and listening for the motor to speed up as the bearings settle more accurately onto the shaft. That's interesting about resistors, does it show where they are on any documentation? No flywheels?
 
I just re-read and noticed your remark about the flywheels. The fact also that this slow down has only happened since fitting the decoder, seems to point more in it's direction than the motor. I wonder if these resistors are built in and there's alternative power take-offs on the decoder to bypass them.
 
Well, here are the instructions:
Bach-DSLv35-2006.pdf
https://ncedcc.zendesk.com/hc/en-us/article_attachments/202860985/Bach-DSLv35-2006.pdf

And I was wrong. It says Capacitor, not resistor. And it's kind of a mute point as there none of either on this loco. I have looked for them time and time again thinking I must have missed them somewhere, but no. As I tried two different decoders with the same result, I doubt it would be THIS decoder that is the problem, but running DCC in general? (Decoder install was a conversion from DC.)
 
AH SO! these capacitors are on the MOTOR, not the decoder, are they where they're shown in the PDF photo? It's them that have to come out, the orange/yellow ones with 104 on them, not the blue/green ones. By the PDF illustration they're blocking access to one of the brushes, and as you've got both brushes out, they may be elsewhere (say's they might). Have to hunt them down. Either that, or it never had them and it's a different electrical set-up.
 
On the Bachmann spare parts page they show the GP40 has two different motors, one with the Caps and resistors
and one without, I don't know what loco the one with the caps and resistors go into as mine does not have any of
these on the motor. My loco was running fine for a few years, then suddenly it slowed down, I'm using a Digitrax
Superchief 8amp system and the loco does not start up until I'm around a speed on the throttle about 40, this is both
with the speed table enabled and without it, and with a decoder changed, so I can only think it is the motor.
If any of you guys can up with some other idea I would be happy to give it a try. In the mean time I have ordered
another motor and a couple of shells from Bachmann.

http://estore.bachmanntrains.com/index.php?main_page=index&cPath=66_68_185&sort=20a&page=2
 

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Retired Alex said:
Have you tried adjusting the CV values to increase top speed? See page 4 of the instructions.
Click to expand...

Oh yes. Many times. Both with speed curves and without.

peroni said:
On the Bachmann spare parts page they show the GP40 has two different motors, one with the Caps and resistors
and one without...
Click to expand...

You beat me to it on the motors.
You know, the more I research, the more I think I should do more of it before I post. BUT, some of the questions raised here make me think of other things to research. The one with the capacitors is for the EU market to comply with their anti-interference laws. My loco has the other one.

Also while researching, I found the top speed for a Prototype GP40 is about 70 mph. I think I may just spend some time re-mapping my speed curve to get better performance out of the lower speed steps. Unless there's something good on TV... oh, look... there is... :p

Peroni, what motor did you order for yours? I looked a bit at the Northwest Short Line 2032D-9. I used one when I remotored my Rivarossi Hudson. It's a great motor and should fit in the housing without issue.
 
I ordered the motor without the resistors and caps, because that is what it has in it already, I can't see how the one with the
resistors and caps could fit as the motor touches the top and bottom of the frame as you photo shows and there is no room on
the side as it is a neat fit into the shell. Bachmann have emailed me that they have already sent the motor and shells by USPS
so I don't know how long it will take to get to Australia, but will let you know if that solves the problem.
 
peroni said:
I ordered the motor without the resistors and caps, because that is what it has in it already, I can't see how the one with the
resistors and caps could fit as the motor touches the top and bottom of the frame as you photo shows and there is no room on
the side as it is a neat fit into the shell. Bachmann have emailed me that they have already sent the motor and shells by USPS
so I don't know how long it will take to get to Australia, but will let you know if that solves the problem.
Click to expand...

Ah....So,,,,,another invader eh! I find it usually takes about 3 weeks, 14 days to land here then it's in the hands of AusPost (sometimes a courier). If it passes through the entry port by Tuesday, should get to you that week, if Wednesday, probably won't see it till the following Tues.
 
Actually, something you just said, " the motor touches the top and bottom of the frame". Was this only ever a DC loco, not DCC ready i.e. the motor isn't insulated from the frame. An insulated motor is an essential requirement for DCC operation. If it isn't, I'm amazed it runs at all.
 
It is the same loco that you have, I should have said that there is no room at the top or bottom of the motor for resistors and caps
as there is only a slight gap both top and bottom, and yes it was a dc loco until I changed it to DCC, but don't forget I said that it
was running for years as DCC then a few weeks back the slow down problem started.

No, I wouldn't say invader, I helped prop up the American Economy, everything that I have for the layout and all my Locos and rolling stock I bought from the States over $10,000 worth, so I look on myself as helping our friends out.
 
peroni said:
No, I wouldn't say invader, I helped prop up the American Economy, everything that I have for the layout and all my Locos and rolling stock I bought from the States over $10,000 worth, so I look on myself as helping our friends out.
Click to expand...

Glad to here the new motor solved the problem, they do eventually pass the point of no return, As far,as helping out the US economy, I think I'm substantially out ahead of that figure. I tend to place my hand across the eyes with just enough gap between the fingers, so one eye can make out the purchase button to place the pointer and click it.
 
I, once again, lost an hour or two of my life to adjusting speed curve CV's. It is far more acceptable now than it was before, but a new motor may still be on the horizon. We'll see.
 
KB02 said:
I, once again, lost an hour or two of my life to adjusting speed curve CV's. It is far more acceptable now than it was before, but a new motor may still be on the horizon. We'll see.
Click to expand...

The speed steps you set your cab to will also affect the way it accelerates up through the range 0-128. I don't think my NCE even recognises 14 steps (would be very coarse) but 28/128 are available to choose from. 28 requires less twiddling/movement of the speed control, but 128 is smoother
 
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