I just purchased this model, a DCC ready Russian Decapod. it ran fine on the test track in the hobby shop, but it won't run on my old dc layout at home. It seems that the five large engine drive wheels short out the power supply and pass current directly from one track to the other. (I checked with a volt-ohm meter.) Any thoughts please?
Does it run at all. If it does not, check the tender trucks to make sure one of them did not get turn around.
Hi RAM:
Many thanks for your reply. I believe the tender trucks are correctly aligned. The loco does not run at all and as soon as I place the loco on the track and start to increase the throttle control the dc power pack circuit breaker trips out. Really strange since it ran fine on the test track in the hobby shop. Any further thoughts would be greatly appreciated. Thank you.
Dear Wincoll,
My "lazy" answer would be to tell you to take both your loco and power pack to your hobby shop and let them trouble shoot them.
Digital, or old analog Ohm-meter?
What range is your Ohm-meter set to? (Should be on its lowest setting.)
How many Ohms just touching the two probes together? (For meter and probe "zeroing".)
With the loco off your track, How many Ohms do you read touching a left, and a right drive wheel?
If you want to continue, take a reading across every L-R pair of wheels on the loco and tender, with the tender harness plugged in.
Thanks.
Sincerely,
Joe Satnik
Dear Joe:
Many thanks for your reply. Regarding my volt ohm meter - it is a commercial grade digital Fluke (manufacturer) model, accurate and calibrated.
With the tender connected I get these continuity readings across each pair of loco drive wheels, starting with the front pair: 6.5 ohms, 7.5 ohms, 13 ohms, 6 ohms and 7.5 ohms. I'm thinking that this is a problem. If I put the tender on the track on its own the rear reverse light comes on with the power pack reversing switch thrown, and the power pack circuit breaker does not trip. Anytime the loco is on the track the circuit breaker trips.
Any further suggestions would be much appreciated. Thank you so much!
Since the tender doesn't short the power pack, they could still be a problem. If both trucks were turned 180 degrees, they are our of phase with the drivers. IE: the front truck gets power from the right rail, while the driver gets power from the left rail and the other way around. This will cause your short. With just the tender on the track, the front truck gets power from the right rail and the rear truck form the left rail. This completes a circuit to light the back up light. When the loco is put on you get the short. Joe
Make sure both trucks did not swivel. Doubt that could happen but you never know. Not all Bachmann tenders allow 180 swivel.
Rich
Hi, Wincoll.
I was expecting 9 ohms or so, but 6 Ohms is not out of the question.
I suspect your power pack circuit breaker may be faulty (trips too soon), and/or something is binding or needs lubrication in your loco.
Just to be assured of your electrical pick-up situation, please take these readings:
1.) With the loco and tender off the tracks and connected to each other, touch one of the 6 Ohm wheels with a probe.
Take a resistance reading with the other probe to all other wheels on that side of the loco and tender, one at a time, non driven wheels included.
Keep readings in order, front to back of the loco-tender consist.
2.) Repeat for the other side.
Thanks.
Joe Satnik
A DCC ready loco with DC adapter drawing about 500 ma at 12 vdc would be a resistance of around 24 ohms. A calculation I made some years ago.
My Bachmann Spectrum HO 0-6-0T measures about 150 ma at 9 vdc which is about 60 ohms. Only a small open frame motor. No lights.
Rich
Rich,
Please re-read, as I have made clarifications and corrections.
The Back-EMF of a spinning motor reduces the current (I) it draws, thus making it appear a higher calculated resistance (Rcalc).
(Power supply voltage - BackEMFrpm) / I = Rtot
Rtot is the total resistance of: the wiring to the track, the track, track to wheel interface, wheel to pickup interface, loco internal wiring and motor winding.
With "ground" at the Power Pack (-) terminal, here is the circuit:
G----(-)PPK(+)---Rtot----(+)BackEMFrpm(-)------G
What you are seeing is:
Power Supply Voltage / I = Rcalc, which is higher than Rtot.
Hope this helps.
Joe Satnik
Edit: Changed Rcalc to Rtot in 3 places.
Added Italics
Hi All:
Thanks for your continued suggestions. Still no luck, though the loco did finally run half way round an 8 x 4 oval then the power supply circuit breaker tripped. No more action. Starts momentarily and then the breaker trips.
Regarding the tender trucks, I believe they are correctly aligned as they could not rotate without breaking the truck bodies. I'm pretty certain that power for this loco comes from the tender trucks as each truck is "hot" to the opposite track.
Here are the ohm readings that Joe requested, front to back:
Left side:
first drive wheel to front 2 wheel truck - open
first drive wheel to second drive wheel - 0.9 ohms
first drive wheel to third drive wheel - 2.5 ohms
first drive wheel to fourth drive wheel - 1.5 ohms
first drive wheel to fifth drive wheel - 1.9 ohms
first drive wheel to first tender truck wheels - 2.5
first drive wheel to second tender truck wheels - open
Right side:
first drive wheel to front 2 wheel truck - open
first drive wheel to second drive wheel - 1.1 ohms
first drive wheel to third drive wheel - 1.1 ohms
first drive wheel to fourth drive wheel - 0.9 ohms
first drive wheel to fifth drive wheel - 1.0 ohms
first drive wheel to first tender truck wheels - open
first drive wheel to second tender truck wheels - 1.7 ohms
I am using a "Tech II Railpower 1400" power supply with 14 vdc and 18 vac (for switches) and a total capacity of 13 VA. No other power is utilized when I'm trying to run this loco, and I have good voltage at the track (14.4 vdc).
Any further thoughts, or should I return to Bachmann for repair? Can't really go back to the hobby shop as I bought the loco in Maine and live in Connecticut.
Thanks to all for your thoughtful replies - much appreciate the suggestions.
Will (Wincoll)
Hi, Will.
Your pick-up situation looks good.
Sorry that took so much work.
But hey, that's what you get for letting me know you had a good Ohm-meter.
Possibilities:
1.) Something is binding in the loco's drive train.
2.) Loco needs cleaning and lubing.
3.) The motor winding is shorted.
4.) There is a weak (defective or worn out) circuit breaker in your Power Pack.
5.) Your loco does normally draw more than 900 mAmps (=13VA/14.4V),
meaning your power pack is too small.
Can you set up a current test circuit with a dummy load and meter
to pull 600mA, 700mA, 800mA, then 900mA to see if the power pack's
circuit breaker holds?
Thanks.
Joe Satnik
Edit: Eliminated possibility #5, as new research shows much lower loco current draws.
Since the OP has a meter, put it on the highest DC amps scale. Put the meter in series with one lead between the pack and track.
Standard procedure when anyone does a loco amps test before installing a decoder.
Sounds like you have only one meter but this will still work.
Below is what I do with two meters. Has worked for many years, even when all I had were analog meters forty years ago.
http://www.trainelectronics.com/Meter_HF/index.htm
Rich
Hi Joe and Richard:
Thank you both for your further replies and suggestions. Sounds like my power supply is maxed out when I start the loco thus causing the circuit breaker to trip. I greatly appreciate your help and will start with the motor amp draw test, and if it is close to power supply capacity then obtain a larger capacity power supply as I'm expanding the layout anyway. I like Rich's idea of the two volt ohm meters wired up to measure voltage and amperage simultaneously - probably find something at Radio Shack as there're having closing sales.
I'll let you know how I make out in a few days.
Thank you again.
Will (Wincoll)
Hi, Will.
Found a review for your Frisco 2-10-0 loco by Jim Hediger in the April, 2002 Model Railroader on pages 25 and 26.
Scale MPH Load Volts Amperes
9.5 Free 5.5 0.20
13.6 Free 6.0 0.21
36.9 Free 9.0 0.23
55.0 Free 12.0 0.24
Slipping 12.0 0.32
Stalled 12.0 0.51
So, your loco running free shouldn't draw more than 1/4 amp.
This eliminates my previous #5 possibility.
Other possibilities:
6.) Short in tethers,
7, 8.) Short in loco wiring or circuits,
9, 10.) Short in tender wiring or circuits.
Hope this helps.
Sincerely,
Joe Satnik
Hi Joe:
Thanks for this further update. I really appreciate your persistence in helping me identify the problem with this loco. At this point I think I'm going to ship it back to Bachmann for warranty repair.
Thank you again, and happy railroading!
Will (Wincoll)
Hi, Will.
Just know that if they choose to replace it instead of repair it,
you may not get a DCC-ready Decapod back, as they are not currently being produced.
What track voltage does it take to get it moving?
What track voltage does it take to keep it moving? (Before it blows the breaker.)
Is the dummy plug in its proper location/orientation?
Thanks.
Joe Satnik
While I am a great fan of Bachmann Spectrum engines, I own 30 or so of them, the worst has been the 2-10-0.
My two older ones are currently out of service due to pulled wires from the plugs and circuit boards and the newest one, purchased in January of this year has had numerous 'issues', mainly with wires becoming detached from the circuit board when the tender body shell was being removed for kitbashing and adding weight. On the latest model, the tender drawbar is longer than the older models which results in the fall plate between engine and tender dropping down between the tender even when close coupled. All my engine tenders are close coupled. On this engine, the wiring harness is way too long, longer than the usually overly long wiring harness. It's so long it drags along the ties. Yes, that can be fixed by stuffing the wires back into the tender but that also has resulted in detached wires from the circuit board and, of course, all that wire stuffed into the tender just exacerbates the constant issue with the Bachmann wiring harnesses lifting the front of the tender.
My loco also suffered from the 'sitting on the tracks, making all the noises, bell, whistle, hiss, chuff etc.,' while not actually moving syndrome. It also has really poor electrical pick up for a ten coupled steam loco. However, keep at it. The drawbar can be replaced with a home made one, a friend soldered the wires on the tender back for me, thanks Sid, and now the loco is running, albeit with poor pick up, which is the next issue to work on.
Cheers
Roger T.
Hi Joe and Roger:
Again, many thanks for your ongoing feedback and recommendations. Your info, Roger, is not very encouraging! - but I guess I shouldn't make impulse purchases while on vacation! I think I will proceed with sending the loco back to Bachmann for repair.
To answer Joe's question about track voltage etc., I don't know as I only ever got the loco moving once, and on each subsequent occasion the power supply circuit breaker trips as soon as I engage the throttle.
Thanks again, and happy railroading to all!
Will (Wincoll)
Visually check the tender trucks. Look at the wheels. If it worked on the test track at the hobby shop, then it should work on yours. Drivers don't magically go out of phase with each other; the trucks on the tender (I OWN TWO) can swing on one another, and if you don't check that, everything will appear to go haywire.
SGTC.
Hi SGTC:
Thanks for the suggestion; but the trucks on this tender cannot physically swing. Also, the insulated wheel hubs on each tender truck are on opposite sides from the front truck to the back truck. I believe this is the correct configuration.
Thanks again,
Will (Wincoll)
Quote from: Wincoll on April 25, 2015, 08:30:16 PM
Hi SGTC:
Thanks for the suggestion; but the trucks on this tender cannot physically swing. Also, the insulated wheel hubs on each tender truck are on opposite sides from the front truck to the back truck. I believe this is the correct configuration.
Thanks again,
Will (Wincoll)
The front truck should have the insulated wheels on the Right/Engineer's side and the rear truck should have the insulated wheels on the Left/Fireman's side.
Cheers
Roger T.
Dear Friends:
Thank you; I checked the tender truck alignment. It is as it should be, per Roger. So I finally got this puzzle solved and the loco running. Removed the bottom drive wheel retaining plate from the loco and found that one of the copper wipers which is part of the copper bus on the inside of the bottom plate, and which contacts the drive wheels, was not quite aligned correctly and was shorting to ground. Tweaked the copper wiper very carefully - boy these are delicately made - reinstalled and guess what? No more problems and the loco runs great! still a mystery though as to why the loco ran in the hobby store and not when I got home - was very careful in handling at all times!
Thanks again to all!
Will (Wincoll)
Ahhh, Life is good!!!!