Scot Rail DBSO questions.......

[exmouthcraig]

  a lot does confuse me so as ever I throw my dumbness atthe collective in an attempt to learn something 

I am considering converting my Class 47 to sound, I know that the GF sound chassis is on it's way so i might wait for a new loco but as i already have a 47/7 I'm looking at getting a DBSO to allow me to run a proper push /pull set up.

The DBSO is Next 18 i think, so first question....

Is a Next 18 4 function decoder the one that I need?

The sound will come from the Duff so presumably I dont need a sound decoder in the DBSO??

Do these then need to be paired in order for the lights to switch with the direction or are they clever enough to know which way round everything is running??

I dont think I'll ever understand DCC fully 

[Dr Al]

The sound will come from the Duff so presumably I dont need a sound decoder in the DBSO??

DBSO is just a coach, so in real life it makes little in the way of sound (flange squeal maybe, track joints, air con), so you don't need one I'd say, and it won't be designed to fit one (larger chip) either.

Do these then need to be paired in order for the lights to switch with the direction or are they clever enough to know which way round everything is running??

Yes, generally, you can treat it like an HST or DMU where all decoders in the set are best addressed to the same address.

There's nothing stopping you *not* doing that, but you'd then need to change direction on both addresses to achieve the same thing.

Cheers,
Alan

[exmouthcraig]

@Dr Al thanks Alan, I'm sure if I get it all wrong I'll vent my frustration on here 

You never know, I might succeed 

[Dr Al]

When programming, use the loco to program the address of both chips. Some decoders don't like not having a motor load connected when configuring. Then once addressed you can fit the DBSO's chip back into it.

If the lights operate the wrong way on either (i.e. going forward the whites are on at the back or suchlike), change CV29 using this guide to reverse the direction of the offending decoder:
http://www.2mm.org.uk/articles/cv29%20calculator.htm

Cheers,
Alan

[njee20]

The CV29 change only works on the DBSO itself. If the loco direction is out of sync with the lights it won't change that, but then it shouldn't be! You can't program the DBSO decoder in the 47, because it's not Next-18. However programming both at the same time will suffice, ie just put both on the program track together.

You don't have to have the same address for both, you can consist them, which will synchronise the lights, you wouldn't need to reverse both separately. Do this if you ever want to run the 47 separately. If you want to treat it as a permanent unit, like an HST or whatever, then giving them the same address is easier.

I've not fitted sound in a 47, but the Zimo MX660 works really well in other Farish diesels. It has low voltage function outputs, so no additional resistors are needed. It's also single sided and flat, like the stock PCB. 

[Dr Al]

The CV29 change only works on the DBSO itself. If the loco direction is out of sync with the lights it won't change that, but then it shouldn't be!

Off topic, but have you ever seen that? Is it a decoder fault, or is there a CV to correct it? I definitely have one such decoder....

Cheers,
Alan

[njee20]

Not from the factory, but it can certainly happen after a hardwired install, or disassembly. Putting the motor in upside down will do it, as will inverting the grey/orange wires. It depends on the decoder, there are definitely CVs on Zimo decoders to do it, but I forget what they are! Most commonly is a 'matched' pair being the same orientation, as you identify, and then you can simply reverse the dummy for ease!

[Dr Al]

It was a 6 pin chip; not wired, and other chips worked fine in the test loco (as did DC and DCC lighting and motor directions), so I concluded it was not a loco fault.

Cheers,
Alan

[njee20]

That's very odd! Never consciously seen that. Pins 1 and 2, or 5 and 6 being inverted would do it, but obviously that's very unlikely from the factory.

[Dr Al]

That's very odd! Never consciously seen that. Pins 1 and 2, or 5 and 6 being inverted would do it, but obviously that's very unlikely from the factory.

Indeed. Not the end of the world as it's perfectly usable as a lights only decoder or a motor only decoder - but it would be interesting to know why.

Cheers,
Alan