Slightly odd behaviour on DC

J

JonathanJ

South African Railways, Garratts, PRR.
Or, 'Do they all do that?'

Recently bought a Klein Dicke loco split from an LGB digital start set. I Currently run DC, and will for at least the forseable future, so I plonked it on some DC-fed track to check operation under a 'normal' supply.

Starting voltage is a little higher than for non chipped locos, but takeoff is very smooth and controllable and the lights come one first so I don't actually see that as a problem in it's intended duties as station pilot.

BUT, if I run the loco forward at 9-10v or more and then stop it and sharply reverse the polarity - much more quickly than would be prototypical, to the point where something like a stainz might briefly spin its wheel - the electronics seem to get confused for half a second, and it stops and then sets off forward again. An inch or so on further down the rails, it realises its mistake, stops again and starts off backward as demanded by the revised polarity. Do they all do that on analogue?

Obviously when the loco is runnning on DC, the decoder chip is waiting for enough volts to wake up, deciding it's not in a DC environment and only then routing power as needed, and I'm guessing it's just down to it being a bit slow, or maybe some registers/memory locations (in the processor definition, not the DCC one) keeping ghost images of their old settings during power down. Not too worried, if it proves too difficult to control in use, I'm not above rewiring it as a DC loco, but I'd love to know..

Thanks,

Jonathan
 
One question, Jonathan (and just to declare interests to everyone, I'm the seller of the loco in question) - are you using a controller with a forward-off-reverse knob, or one with a speed-only knob and a polarity reversing switch for direction control?
Not sure if or why that would make any difference anyway, but just wondered?

Jon.
 
The short asnwer is no. Normally a DCC chip on DC means a smoother ride than a pure analogue loco, though the chips do feature an inbuilt delay to avoid someone overstressing the gearbox/ connecting rods (and the electronics) through the sort of rapid reversal you've indicated. You haven't said whether the loco was second hand or new from a split set. If second hand there is a possibility that some of the chip settings have been tinkered with. If you have someone local with DCC, ask them to reset CV55 to a value of 55 (factory defaults).
 
JonathanJ said:
Or, 'Do they all do that?'

Recently bought a Klein Dicke loco split from an LGB digital start set. I Currently run DC, and will for at least the forseable future, so I plonked it on some DC-fed track to check operation under a 'normal' supply.

Starting voltage is a little higher than for non chipped locos, but takeoff is very smooth and controllable and the lights come one first so I don't actually see that as a problem in it's intended duties as station pilot.

BUT, if I run the loco forward at 9-10v or more and then stop it and sharply reverse the polarity - much more quickly than would be prototypical, to the point where something like a stainz might briefly spin its wheel - the electronics seem to get confused for half a second, and it stops and then sets off forward again. An inch or so on further down the rails, it realises its mistake, stops again and starts off backward as demanded by the revised polarity. Do they all do that on analogue?

Obviously when the loco is runnning on DC, the decoder chip is waiting for enough volts to wake up, deciding it's not in a DC environment and only then routing power as needed, and I'm guessing it's just down to it being a bit slow, or maybe some registers/memory locations (in the processor definition, not the DCC one) keeping ghost images of their old settings during power down. Not too worried, if it proves too difficult to control in use, I'm not above rewiring it as a DC loco, but I'd love to know..

Thanks,

Jonathan
Click to expand...
My Fo rack loco does this, it's just because you are switching polarity faster than the board can recognise. it's nothing to worry about, but then again, i don't switch directions at that speed.. :rolf:
 
whatlep said:
The short asnwer is no. Normally a DCC chip on DC means a smoother ride than a pure analogue loco, though the chips do feature an inbuilt delay to avoid someone overstressing the gearbox/ connecting rods (and the electronics) through the sort of rapid reversal you've indicated. You haven't said whether the loco was second hand or new from a split set. If second hand there is a possibility that some of the chip settings have been tinkered with. If you have someone local with DCC, ask them to reset CV55 to a value of 55 (factory defaults).
Click to expand...

I sold the loco to Jonathan, Peter (my, it's getting jolly Biblical here all of a sudden...) - it came from the big LGB Digital Starter set (MTS II), which I bought brand new in about 2003, and nothing has been fiddled with CV-wise apart from the loco address being changed. Obviously a CV55 reset wouldn't do any harm, but I'd be very surprised if anything is set wrongly.

Jon.
 
I might just be wrong, but I thought "slightly odd behaviour" WAS ac/dc....... :nail::wave:
 
LGB decoders have an onboard shuttle mechanism built in. If you do a "hard reverse" the decoder will slow down at the rate programmed into the decoder (CV4), wait for the time programmed into it (CV58) & then accelerate in the opposite direction as programmed in CV3
 
To answer questions..

No intention of operating the loco like this, but I was testing it on 2 yards of track on the kitchen table. Sharp reverses (and something soft to stop it if necessary) are necessary under these circumstances if you get any speed up, and I was interested in what I saw.

As Jon/Zerogee notes, the loco is secondhand from him. And I'm NOT COMPLAINING about it, just interested.

The controller I'm using for tests is a gaugemaster OO one with a single forward-off-reverse knob (ie bidirectional, centre off).

I haven't tried setting the loco running one way and then reversing polarity instantaneously with a switch, and don't intend to...

If anybody local to Newcastle (upon Tyne) wants to volunteer DCC running rights, I'll check CV55, otherwise, I'll probably not mess. At remotely prototypical speeds and accelerations, the loco is 100% conrollable and smooth running.

Jonathan
 
55.5 said:
You are welcome to try it here in Darlington should you wish to
Click to expand...

Thanks - don't think it's worth a special trip, but next time I'm heading that way, I'll try and remember to load up the loco and contact you as well.

J.
 
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