Programming DP8 and SC1 combination with NCE Power Cab

[geoffwbasig]

I don't know whether I'm missing something in the instructions but I can't get my NCE Power Cab to recognise or programme the SC1.
The DP8 is connected to the SC1 as per the instructions and the DCC input to the SC1 is from the NCE Power Cab panel. The Dapol signals receive 16v ac from the track bus which is connected to a separate NCE SB3a booster.  If I  have understood the instructions correctly I don't need a separate power supply for the DP8.
I may have missed something obvious and help would be appreciated.

[Paul Harman]

Hi Geoff...

A couple of things to note:-

1. The SC1 has to be on the programming track connection for you to read it rather than connected to a booster. Use direct bit mode preferably if you have a choice.

2. The track bus is not 16V AC at industrial frequency which the Dapol signals require - you need to connect the track bus to the AC input on the DP8 and connect the signal red and black wires to the red and black output on the DP8. The DP8 is designed specifically to do the power conversion from DCC track voltage to 9V DC (the latest Dapol instructions recommend 9V DC rather than 16V AC).

3. The DCC input to the SC1 needs to come from the NCE track output from the booster when operating.

4. There is no need to be able to read the SC1 in order to program it. Just reset to factory default and set CV38 on the programming track, then use the jumper to set the address when connected to the track output.

I hope that helps answer most of your queries.

[geoffwbasig]

Hi Paul

Still a bit confused I'm afraid. I have wired it all up as per your instructions and connected pins 1 and 2 of J5 so that addresses are assigned automatically. I have connected four Dapols so far but they don't operate as expected. For instance if I operate accessory address 1 and press either 1 or 2 for on/off, two different signals operate! If I operate accessory address 2 or 3 again two different signals operate. Accessory address 4 does nothing. Actually I would rather assign the accessory addresses manually in the range 34/35/36/37. I see that there are what appear to be jumper pins on the SC1 at J3, J5 and J6. Do I use these instead of altering the addresses by CV input and how do I know which pins relate to which output?

[Paul Harman]

It sounds like you have not programmed CV38=15. This is most important to ensure that the SC1 has eight separate outputs rather than the four pairs as factory default.

The set the address you need to power off the SC1 by removing track power to it, fit the jumper to pins 1 and 2 of J5, restore track supply and operate accessory 33, then before doing anything else remove power from the SC1 and remove the jumper. Address will then be 33/34/35/36/37/38/39/40. This group of eight will encompass your four addresses 34-37 on outputs 2-5

[geoffwbasig]

Thanks Paul, I'm now sorted. I've reset the SC1 and set CV38 to 15. Actually I thought I'd done that yesterday but I think I operated the controller incorrectly when inputting the CVs.

Now comes the fun bit- I am using JMRI in conjunction with the Digitrains programme on my Android tablet. The instructions in the SC1 handbook seem easy enough so I don't envisage any problems there.

Thanks for your help (and patience!)

[Paul Harman]

Excellent. JMRI will be fine, you can use signal mast logic with the semaphore signals in the BR-2003 signal system.

[geoffwbasig]

Further to my last post on this subject I am finding that on random occasions the SC1 is losing its setting on CV38 and consequently the addresses for the DP8 do not work correctly. Upon resetting CV38 to 15 on the program track all is well again. For some reason CV38 goes to a value of 0 which appears to be a default setting. Do you have any ideas what might be causing this behaviour and is there a CV setting which will lock the decoder?

[Paul Harman]

The only reasons I have seen for the SC1 reseting to factory default unexpectedly is when the track signal to the SC1 is interrupted rapidly (usually with short circuits causing the track power to be cut off and reaplied rapidly due to an ongoing short) or due to brown out conditions when the track voltage drops to a very low level (usually cause by thin wiring prevent the overload protection from cutting the track power when a short occurs).

If the track signal is solid and continous thare is no problem.