DCC so frustrating at times

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aldothenoo
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DCC so frustrating at times

Postby aldothenoo » Sat Mar 31, 2018 9:39 pm

Hi guys I've recently switched over to DCC and it's not as easy as I first thought. All my locos rang absolutely fine just on DC with no hassle with decoders and such like. My gripe is I have a few bachmann class 66s which ran fine DC but on DCC just run jerky or at full speed. I read online that older models of this loco required if jerky to cut the capacitors under the board housing the decoder. I cut the capacitors and low and behold the engine won't move at all now. Just dead. Lights are on but no power to the motor. Seriously fed up tonight. Just seems the locos need a lot more tlc than on standard DC. I know tomorrow's another day. The reason I switched to DCC was the sound which I must admit is fab. Can anyone recommend a solution to the bachmann class 66 jerkiness. Must mention I have cleaned the pick ups and track on the said locos. Any feedback would be greatly appreciated Alan

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Roger (RJ)
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Re: DCC so frustrating at times

Postby Roger (RJ) » Sat Mar 31, 2018 10:50 pm

Sounds like you have cut the wrong components. Snipping the capacitors should not stop a loco from running. The capacitors are normally on the motor itself but there are exceptions.

What decoders are fitted in the stuttering locos?
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aldothenoo
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Re: DCC so frustrating at times

Postby aldothenoo » Sat Mar 31, 2018 11:22 pm

Hi Roger thanks for the reply. I looked at the Bromsgrove website for the older bachmann class 66s which I have and it was in diagrams pointing to what to cut. It was definitely the capacitors I cut which were yellow topped located under the PCB board. I'm gutted it's now not working. Ok the decoders....I have LAIS DCC decoders which I have in other locos and have been fine. I have tonight ordered a lens 8 pin decoder which is a better range of decoder and I'll try this in my other class 66.

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Mountain
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Re: DCC so frustrating at times

Postby Mountain » Sat Mar 31, 2018 11:32 pm

If you cut the capacitor and it stopped working, then are you sure it was a capacitor? The TV supressor capacitors are normally wired in parallel. To stop the motor from working you would have to cut something that was wired in series. The lights will be on a seperate decoder circuit so won't be effected.
Last edited by Mountain on Sat Mar 31, 2018 11:33 pm, edited 1 time in total.
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MickleoverTestTrack
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Re: DCC so frustrating at times

Postby MickleoverTestTrack » Sat Mar 31, 2018 11:33 pm

I think the most likely explanation, since the lights are working is that, in cutting the capacitors the movement has caused one or more connections to fail.
This is quite common with older Bachmann locos in my experience, the wires to the motor are very fine and break easily or the solder may have come away leaving a dry joint.
The solution is to strip back the motor wire and re-solder it.

To be honest, I've had this happen to an old 159 motor chassis in use on DC without it even being opened, so staying DC is not an insurance policy against it happening.

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Bufferstop
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Re: DCC so frustrating at times

Postby Bufferstop » Sat Mar 31, 2018 11:34 pm

Sounds to me like you've also cut one of the motor wires, they are likely to share a soldering point with the capacitors, that would explain lights on but no motor. Wait, take a deep breath and then another look, if necessary through a magnifying glass. The person who attached the wires in the first place will almost certainly have been looking through one.
Looks like at least two others have come to a similar conclusion.
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aldothenoo
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Re: DCC so frustrating at times

Postby aldothenoo » Sat Mar 31, 2018 11:38 pm

I've done a bit of research on the older baccy 66s and quite a few people are saying they do run jerky on DCC. My policy is I buy the cheaper DCC decoders although I do have a few locos on guagemaster decoders which run fine and so do the so called cheaper decoders. Like I said I have ordered a more expensive option of decoder for my other 66s and I'll see if that solves the running issues.

Bigmet
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Re: DCC so frustrating at times

Postby Bigmet » Sun Apr 01, 2018 8:58 pm

aldothenoo wrote:I've done a bit of research on the older baccy 66s and quite a few people are saying they do run jerky on DCC...

I would disregard such opinions completely. If the mechanism ran smoothly on DC, then it will run smoothly on DCC: but the DCC system and decoder have to be of competent design and manufacture. The problem with DCC is that as a system it is a 'black box', in that very few people will ever look at the quality of the signal and signal processing because the tools required to do so are expensive and require a knowledgeable operator. So you need some guarantee that the DCC system and decoders do the job correctly.

Briefly, in DCC you get what you pay for. Buy from one of the established system specialists and it is excellent. Cheap knock off decoders from China, poorly engineered in house systems from model railway makers, very much second rate. I went largely Lenz on this basis, and with a few other decoders from Zimo, ESU and CTE get superb perfromance from ordinary RTR without exception, including as it happens a Bach 66. I have seen the generic cheap Chinese decoders through some friends whom I help by performing decoder installs. They find the price attractive, but not the operational charcteristics, and come back with "could you try tweaking the CV's". The answer is no, that's the best performance I could persuade it to deliver: now here's that same loco with a Lenz standard, and wouldya look at that, it is smooth, has a good speed curve and is reliably controllable, and thats the same mechanism, running on the same DCC system power. You get what you pay for.

Mike Parkes
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Re: DCC so frustrating at times

Postby Mike Parkes » Sun Apr 01, 2018 9:43 pm

Some Bachmann models have capacitors across the motor contacts and chokes (or something else) in line with the motor. I have mistakenly removed both and found the loco to be dead. It was easy to correct once I realised what I had done by adding wire jumpers across the location of the mistakenly removed components, the decoder seemed to fulfil the function of the mistakenly removed components and performance was not affected. Best thing to do is remove the decoder and test the connection between the dcc socket and the motor with a multimeter set to resistance - if a 8 pin socket then 1 and 5 should be linked to the motor, if its a 21 pin socket 18 and 19 go to the motor. If you find that their is no connection trace the circuit to see if you can work out where the fault is and correct it, or make a new connection between the socket and the motor using any suitable solder pads/pins that exist.

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Bufferstop
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Re: DCC so frustrating at times

Postby Bufferstop » Sun Apr 01, 2018 11:31 pm

The original existence of the chokes (inductors) makes all the difference to the explanation, if you literally snipped them out it should be possible to see the stub ends of their leads on pins 1&5 or 18&19, it is then purely a matter of tracing the wires from the motor and linking them to those pins. Although they are pretty much redundant once a decoder is fitted, there removal is sometimes not suggested due to the need to replace them with a link.
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