I recently recieved a rivarossi big boy 4011. When I place it on track with a DC power source and turn the throttle up, the engine kind of buzzes or hums a bit before it actually gets started. It starts moving just below 4 volts, but only after humming for a bit. The much odder thing is that if I switch the polarity/direction of the DC current while it is running it just keeps on going in the same direction, still responding to throttle changes.
Is this what DCC does when on a DC layout? I don’t have a dcc system to test with.
I can think of some reasons for the slow start every time, but not the ability to switch polarity while running.
It came without a box, used, untested, so no advertising about dcc.
Looks like I’ll have to open it up at some point to see exactly what it has, or get a dcc system. I’ve heard some decoders can get burnt out running dc too much, so I don’t want to do that.
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I cannot confirm it, but I found one source that says the 4011 was made in 1998. That doesn’t mean it was or was not DCC or was or was not converted to DCC.
DCC now, not sure about 1998, can be dual mode, meaning they can be programmed to run on either. Internet wisdom is that allowing DC mode on a DCC system can cause run away behavior.
I always assumed that a DCC loco, programmed to only run on DCC, would do nothing on a DC layout. It never occured to me to test that hypothesis. Someone has I am sure.
I can’t explain the failure to respond to reversed polarity.
I have a Bachmann Spectrum 2-10-2 that does this. But only with my MRC Tech 6 in DC mode. When powered by the Tech 760 or 780 it changes direction normally.
Someone has put a decoder into your locomotive.
What type of DC power does your powerpack produce?
Have you tried a different powerpack?
A decoder equipped locomotive with DC (analogue) switched off in CV29 will not run at all in DC mode so that’s not it.
My guess is it’s that your particular powerpack is putting out PWM DC power and confusing that decoder. Try a more recent DC powerpack if you can borrow one, or a DCC to test how it runs with the decoder active.
If it has a decoder it will be in the tender. A decoder will have at least four wires between the tender and locomotive. A DC Rivarossi or non DCC locomotive will only have the drawbar for power from the tender to the locomotive.
The older Rivarossi (pre 1995) motors do have a lot of motor noise and draw a lot of current.
Could be a decoder was added and unless it has the capacity to drive the older motor the high current could have damaged the decoder causing erratic running.
EDIT:
The Rivarossi articulateds make great runners so don’t give up on it.
I thought I replied to this earlier and was waiting for it to be approved, but maybe I never actually hit post. If theres two of my posts in a row thats why. Anwyays heres for the new replys
“Was it advertised as having DCC?”
No, I bought it used untested without box
“What type of DC power does your powerpack produce?”
I’m not sure, its a MRC tech II loco-motion 1500. I know it’s pretty old but my other engines until now have mostly been older and all DC.
The only other even semi-modern power pack I have is a bachmann spectrum. Tried that and it would start up then stop constantly, never getting to any decent speed.
“In the tender”
I’ve seen other rivarossi locos that have tender electrical pickup but this particular one can actually run without the tender
After seeing these replys I ended up taking it apart. I hadn’t wanted to originally from previous experience with steam engines being complicated to put together, but this one only ended up only needing 2 screws removed to access the drive system, top just lifts off. Decoder (I assume) pictured below
It’d be a shame to not run this for fear of damaging the decoder, so I may resolder the wires directly to the motor until I get a dcc system. Seems silly to remove DCC but it may be a while before I can get my hands on a DCC system.
If it has a motor decoder, it shouldn;t make any noise untilt he voltage gets high enought o move it, any more than a DC loco would - it’s possible for the motor to buzz slightly when it’s just under the threshold of having enough power to start the loco moving.
If it’s a sound decoder, at around 5 volts or so it should start making the basic boiler hiss sound, and then at slightly higher voltage, start moving and making the chuffs.
For a 1998 vintage, it’s VERY likely that it could have a sound decoder that does not operate on DC. Many older decoders, and especially sound ones, were DCC only. That could account for the strange noises.
I don;t think Rivarossi offerend them with sound at that time, so if it has a decoder, it was added by the previous owner at some point. If added at the time the loco was new, it’s very likely not dual mode and won’t run on DC.
Locomotive is moving under DC power only so whatever the problem might be it cannot be a decoder not able to run in DC mode.
Because it won’t respond to the reversing switch on the powerpack and it only starts to move at 4v I suspect a non sound decoder has been installed and it doesn’t like the type of power the OP’s powerpack is delivering to the track for some reason. I do know decoders do not like “momentum” switches on MRC Powerpacks. I’m guessing the MRC Tech II may not be suitable for that decoder. Wonder what brand and model that decoder is? Looks almost stone aged.
Also, note this Tech II powerpack delivers pulse modulated voltage at 60 Hz for very good low speed operation of DC locomotives. I am no DCC expert but I predict that’s the cause of your symptoms. That explains the hum without movement followed by a lurch to a relatively fast speed. That pulse power may also interfere with the decoder’s ability to read reversal of rail polarity.
Similar electrics can be used to “trick” a decoder from QSI into operating decoder effects like bells and whistles. For QSI decoders running DC mode flicking track polarity while the locomotive is moving signals the decoder to make sounds. The frequency of the flip is determined by your manual dexterity, fast or slow flips produce different effects. That generates a very slow AC signal within the DC power delivery.
For very slow speed motor control your MRC Tech II 1500 switches voltage from some x value of DC volts to zero volts at about 60Hz (much, much faster than your finger could manage). The decoder sees that as some kind of instruction signal rather than a power to the motor signal. When the pulsing stops the dec
A quick google reveals anecdotal reports of “decoder frying” with Tech II but Rapido does not blackball these powerpacks. If anybody would the ever vigilant Rapido would, I should think.
Failure of a decoder to operate as expected might easily be reported as fried when it is just fine but can’t use the DC power as delivered.
New DC powerpacks are pretty cheap and more recent used models are even cheaper, getting down to the price of some DC only locomotives.
Unfortunately I can’t see the OP’s pics on this computer, so I’m kinda shooting in the dark. Anyway, in recent years, all decoders have been “silent” decoders, early decoders often had a noticeable “buzz” sound when power was applied. I still have 3-4 of them on my layout, both sound (Digitrax “LC”) and non-sound.
It being noisy doesn’t mean there’s a problem or that the decoder is being harmed, it’s just noisy. You can either replace it with a modern dual-mode decoder (maybe $15-20 if you shop around) or if the engine uses an eight-pin DCC receptacle, you might be able to track down the correct “dummy” plug to convert it back to DC only.
I also have a quite lovely Lifelike Proto Heritage 0-8-0 that does not like to run in DC mode at all with its decoder connected.
Using the Tech 6 in DC mode produces similar behaviour to the OP’s Rivarossi although reverse function works. Nothing but humming until the voltage reaches a threshold and then she shoots off at fairly brisk clip although nowhere near full voltage nor anything like top speed. Just lurches into life all of a sudden.
Same loco runs sweet as anything on DC track with the decoder bypassed and even sweeter on DCC track with the decoder in circuit.
Were it my Rivarossi and I wanted to get good DC operation and preserve DCC capability I would unsolder the decoder, solder it to a nine pin plug. Or fit an 8 pin if that’s preferable, the Rivarossi won’t need that 9th wire anyway and the decoder you have is for an 8 pin. There’s no harm wiring an 8 pin decoder to a 9 pin plug as long as you get the wire colours in the right order. 8 pin are rectangular and 9 pin are linear plugs. Then solder a 9 pin socket (or 8 as the case may be) in place of the now hard wired decoder. Plug in a dummy plug and start saving for that DCC equipment you know you really want.
My reasoning is that once you get the locomotive apart and take the trouble to unsolder the decoder why re-solder for DC only? It’s hardly more work and only a little more expensive to wire in a socket for the decoder (dummy plugs are maybe $5 new and can be as low as zero used). I’d solder in a 9 pin socket and fit a 9 pin dummy plug to run DC only with your existing powerpack. Then you can refit the original decoder (which probably works just fine) anytime you want or have the option of upgrading the decoder whenever you wish by simply plugging in a new one.
If the OP wants to put a dual mode decoder into to it and run it on DC, he will have to turn the pack up to five volts for the decoder to wake up and about seven volts for the loco to move. Nature of the beast.
You really cannot over emphasize that point about “dual mode” decoders. They really aren’t dual mode and the behaviour of some locomotives when so equipped is often unsatisfactory compared to either DC or DCC. Older designs with current hungry motors seem particularly unsuited for dual mode operating. Better to consider “dual mode” as dummy plug DC direct or decoder managed DCC.
Dual mode in the more recent locomotives allows reasonable operation of DCC equipped locomotives on DC powered track but these still won’t play nice with the real DC powered locomotives. That means you are in reality running dual systems not DC only. You can end up with duel mode rather than dual mode.
If you can, a better system is to provide for DC power to the layout only when you want to run your older DC only locomotives. When you’re done reminiscing about those old days, take them all off (or very carefully park them where no DCC power can ever reach them, even through a rolling stock metal wheel bridging current) and switch over to DCC for the rest of the session.
Dual mode locomotives can stay on the layout all the time, even operate if you wish. But actually running DC locomotives at the same time as trying to run DCC locomotives in DC mode just isn’t very pleasant. You are really just running two entirely separate railroads sort of mushed together. And you aren’t getting the best out of your DCC equipment to boot.
There are two types of dual mode locos. Those with, and those without sound. I can’t imagine anyone is actually happy running sounds ones on DC, but it appears many are.
It is absolute unavoidable, unfixable, unsolvable, that a dual mode sound loco is going to require you turn turnt he power pack up pretty far before the loco moves. This is to get enough voltage to power the electronics, so the stationary sounds can play without the loco already creening around the layout. Leaving little control range between sitting there simmering and flying at full speed. Effectively impossible to run with any ordinary DC loco. And how you would run this with a DCC loco, I have noi idea - because if you put it on DCC track, it will run as a DCC loco, and be perfectly controllable like any other DCC loco.
And then there are ones with motor only decoders. They don’t have as huge a voltage drop, because there’s no sound circuits to start up. Still will be slower at the same throttle position than the same loco with no decoder. On DCC - again, it won;t be running in “dual mode”, it will be runnign in DCC, and work like every other DCC loco.
Almost every DCC loco sold today, sound or not, is dual mode. It’s mostly older ones that weren’t - so to the point of ANY DC power pack causing circuit damage, hence internal jumper plugs to select DC or DCC withotu actually removing the decoder. Other than that, some people turn off DC mode in their decoders - I do in mine, I never run any of my locos on DC, and disablign DC in the decoder can help prevent the loco from taking off at full speed if there is some sort of interruption of the DCC signal to the rails. If you have DCC capability, there’s no point running a decoder equipped loco on DC.
