Deborail

My Dapol Class 121 recently won’t run. It will make a whining sound and run very slowly or stop. The motor is obviously running but somehow the energy is not being transferred to the wheels.

When the irregular behaviour starts the current spikes to 1.0 - 1.5A and the DSO across the rails displays this. Then the decoder does it’s protection thing and the current drops back to the normal 100 mA or so. Seeing these seesaws on the waveform can one assume an internal problem in the motor?

It’s not easy to send it back to the uk.

Further experiments showed that in dc and in DCC using either a imperious or a ESU decoder the loco has a problem. It draws a lot of current starting at 300 mA then in a few seconds going up to and settling to 1A which is really excessive. Then it stops. The lights flicker faintly. The current drops to zero. The decoder probably shuts itself down. Next power up the cycle repeats. Examination of the PCB has not shown anything abnormal.

I have I stalled a new ESU decoder in my new Royal Mail class 128 DPU and it works fine-confirming that the earlier locomotive had a fault. Installed it with the CV29 value as ‘2’ address ‘28’...for some reason it wouldn’t move if I set the address to ‘128’. I think that is because in AD2 that would be considered as ‘0’

I am not sure mate, but anyway, I am posting it back to the Seller today, it is the Scooby Doo Weathered version. I have found a Royal Mail version on ebay and purchased it. I also ordered a few ESU decoders. Hope for the best going forward...

He said that he prefers to refund.

I have decided to return the locomotive to the seller for a refund. I think I lost three decoders, but I have a feeling that I would lose more going forward using this locomotive. I will source out another 128 later on...hopefully that would work well with DCC.

I will try Lenz. If it blows this too I will let it be a DC loco.

I have contacted Heljan and they said that their motors need robust decoders such as ESU. I was told to use ESU. They said cheaper decoders cannot handle the load of the motor on this locomotive. So far the decoders used were digitrax and a couple of Dapol Imperiums

Thanks for the very eye opening information. I have lifted the PCB which is mildly stuck onto a black plastic surface. I have added a layer of insulation tape just in case. The underside of the pins does not show any soldering overlaps. Pins 1 and 22 do not seem to be shorted. The motor pins 19 and 18 have a suitable resistance between them. All seems very normal. The problem is that to test any further would run me the risk of blowing more decoders. I am getting resigned to the fact that this is destined to become a DC only loco.

It is also surprising to me that this would happen on the programming track, but it did during the programming of the third blown decoder. And the locomotive did move forward as well. It moved significantly. However I have tested other locomotives and decoders on the programming track and all is normal so I don’t believe there is something wrong in the programming track.

Yes, with the blanking plug removed there is no continuity from the track or wheels to the motor connections whether bogies are straight or pivoted ...

Make it three decoders. It has fried a third one on the programming track. I decided to try one more. Still operates fine with the blanking chip in DC mode though. Current draw in DC mode is 300 mA tops. the metal chassis is not electrically connected to the rails. DSO does not show any abnormal wave pattern. I will try to ask Heljan for help before burning any more decoders.

You’re right . but I get a message of ‘writing is completed OK’ on the controller. All the loco lights flash during the writing job.

Yes tried this in another loco reading doesn’t work all values are zero. Writing works.

Programming the decoder works okay. When it is read then all values are zero. Does this indicate a damaged decoder or bad contacts? furthermore when resetting the CV 8 to 8 the controller says ‘no decoder ACK pulse!’ does this mean that the decoder is RIP?

I have tried to read the decoder and all is reset to zero. I tried to reprogram and that works. Then on the main track no response. Then back onto the programming track reading reports zero again. This means that the decoder resets itself when on the main track.

Hi, perhaps that particular decoder was bad, but then why did the DPU also disable my imperium? The loco runs fine on DC, but there is a bit of a hissing sound as is to be expected... No, it doesn't run hot on DC.

I used a digitrax 166 decoder on my new Heljan 128 DPU and the decoder burnt. The locomotive still runs fine on DC though. I tried with a Dapol Imperium and that too became unresponsive although there was no burning. Both decoders are not accessible on the programming track indicating that they have failed. Am I using decoders that are not suitable for this locomotive? What sort of current does this locomotive draw? In the picture the burnt hole is visible.

Hi I have received a new class 33. I have installed a DCC decoder (8pin gaugemaster) does this model have red tail lights or is my decoder installed the wrong way round? thanks...

Hi Friends I have recently Purchased a Dapol Class 29 to which I fitted a Dapol Imperium 21-pin decoder...the locomotive was running well for a week or two but now it has developed a problem. While running it stops and the lights remain on but at half intensity. A faint sound is heard from the motor. Nudging it sometimes causes it to move again but then it stops at another location... i have tried covering the decoder with insulation tape lest there is some Unwanted contact With the main board but this has not solved the issue. The decoder fits snuggly on to the pins. I do not see any short circuit effects - rather a poor contact somewhere. I am not sure what this may be. It must be electrical or dirt related although I haven’t been able to see this. please advise.

It didn’t work...

I have some Trix mfx equipped locomotives and the sound on off is controlled by F2. However, the function only works as a single press. That is if one wants to leave the sound on (the puff puff for steam engines) one needs to keep one’s finger on the ‘2‘ button ... I wonder if this can be solved during CV programming. MFX decoders Auto program themselves when linked with a Trix mobile station. This is not so with the zephyr. CV29 value is 34.

Well, managed to fit in a R8249 with my clumsy porky fingers. I managed to damage the plastic rail on the lower side while trying in vain to pry the body off. It is the hardest ever body to remove, after you actually locate the concealed screws and even then you are left with a dilemma of using too much force or cracking it up like an egg. What worked with me was the gentle left right rocking motion that finally got the body off...It will set your heart racing and it is very possible to break something along the way. Even when the body came off, it didn't do so completely. There is a plastic wire hose thingy on the front that clings on so you can't really part the body shell from the interior. Still, I was able to plug in the R8249 while easily removing the blanking chip. The wires must be neatly folded and the decoder insulated. It all fits neatly into the front area which is tiny. After testing I clipped it back together, screwed the concealed screws and fixed back the couplers. It wasn't easy overall, and it was very easy to do damage. So it is a yellow signal for those wishing to do work inside a Bachmann Class 08...