Dapol 156 lights don't work on DCC

[jpendle]

I have 5 156 sets, 3 powered and 2 dummies. I am using Zimo MX622N decoders. On my DC test track lights work on the powered cars and the dummy trailers. On DCC lights only work on powered cars. I have tried 2 decoders so far and both work fine in the powered cars but not in the dummies.

 

I also used 2 MX622N's in a GF150 and its lights work fine.

 

Oh and the switch at the bottom of the 156 is on.

 

Any ideas guys?

 

Thanks,

 

John P

[Vonzack]

How are you programming the decoders which are going into the dummies, sounds like they haven't got the correct addresses. Dial up 3 on the controller and see if the dummies respond to F0.

 

Either program the dummy decoders in the power cars first and swap them over or, but both power and dummy on the programming track and program together as they are using the same decoders.

 

 

Sorry if I'm teaching you to suck eggs, but not much info to go on ;-)

 

Cheers, Mark.

[jpendle]

Hi Mark,

 

So more details. I'm programming both decoders to the same address (11) in the powered car, lights work fine on the powered car but not on the dummy, I thought it might be a fault on the dummy car so I tried the same chip[s in two more and got the same problem. The decoders are brand new and the only CV I've programmed is the address. I haven't even bothered programming CV29 as at the moment I don't care which direction the lights think they are on I just need them to work. I tried a TCS EUN651 decoder yesterday and it had the same problem. All the decoders work fine in loco's, lights on at both ends which change when direction is reversed.

 

Regards,

 

John P

[Nigelcliffe]

So, reading what you've described, I conclude the decoders are fine. The decoders appear to work correctly in other models.

 

That leaves two possibles - decoder installed upside-down in the trailer car (easily done), or trailer car wiring faulty.   I've met faulty wiring on Dapol models before, though no specific experience of this model.

 

If suspecting faulty wiring, a multi-meter and a DC power source, and a bit of careful prodding of volts to various contacts on the trailer (without decoder present) might reveal what's wrong.  The lights should be on if their pin on the decoder is negative, and the positive should be one one side of the pickups. 

 

- Nigel

[Izzy]

As the decoders work okay in the power units, and the dummies units lights work okay on DC, which would seem to indicate the wiring is okay with the blank plug fitted, perhaps the issue is that the decoder pins aren't making proper contact in the sockets. I now usually bend the pins a little, kink them vertically using small pliers, to ensure they are a firm fit. Be careful to ensure you aren't pushing them in too far. I can't remember with my Dapol 156's, but some Dapol models seem to have bits behind the sockets where the pins can protrude and which can cause them to short.

 

Izzy

[jpendle]

Thanks guys.

 

Took another look today and it seems to be some kind of contact problem on the dummy cars. If I press down firmly the lights work fine, however on my DC test track I don't need to press down on the model. I've checked the wheels for continuity and they seem to be fine, if I remove a bogie I get contact between the wheels on the other bogies and the brass contact strips where the first bogie has been removed. I just need to keep digging into this.

 

Regards,

 

John P

[SRman]

My first thought was (as per Nigel's suggestion) that the decoder plug in the trailer car needs to be rotated 180 degrees. However, John's last post has confused things a bit. I wouldn't expect it to be a contact problem if it works fine on DC.

My best thought: try reversing the plug - no harm will occur to the decoder or lights if this doesn't work, and it will eliminate one possibility. If it does work, then problem solved.