DCC to DC

[Potterton]

Just a general enquiry and please forgive my ignorance of all things DCC.

I'm interested in purchasing a second hand loco which is DCC fitted and described as "will not run on DC." If I were to purchase this loco would it run if I simply removed the decoder or would it have to have a blanking plate refitted?

[Going Spare]

That depends upon how the decoder has been connected. If a socket was available, a blanking plate will be needed, or removal of the socket as well and restoring the wiring providing a direct connection between pick-ups and motor. If a socket was not pre-fitted or introduced and the decoder was hard-wired, the pick-ups-to-motor wiring will need reconnecting when the decoder is removed.

[96RAF]

It will run on DC if you have access to a DCC controller to change CV29 to re-enable DC running. Some decoders default this to off.

[Fishmanoz]

Putting Rob’s another way, DCC fitted locos will run on DC unless DC Running has been disabled in the decoder in CV29. So there is no need to remove the decoder if you can find someone with a DCC controller to turn DC Running back on.

[ColinB]

Although if you change CV29 to a 1, the loco will run on DC, I have found that it doesn't run quite as well as if it didn't have a DCC decoder fitted. I did a test with one of my locos by running it with and without a Hattons decoder. With the decoder fitted it needed a higher DC voltage to get it moving. It could be something to do with the PWM out of my Hornby controller but I don't have a true DC source to test any further.

[Howbi]

That is incorrect, a value of 1 only changes direction. New decoders usually have CV29 set to 6.......2 for 128 speed steps plus 4 for DC running.......HB

[Potterton]

Thank you for the replies chaps. Where can obtain blanking plates? I am aware that I would need specific ones for specific locos and that there is no "one size fits all."

[Howbi]

This is one solution using copper speaker cable. Join pins 1 & 8 and pins 4 & 5

[96RAF]

@colin

The reason it takes more throttle to get a decoder equipped loco going on Dc is because the decoder requires a certain voltage to boot and recognise that it is seeing DC not DCC hence the lag.

@pott

Howards shorting link will work fine as long as you don’t have need/lights.

[Potterton]

@Howbi and 96RAF

Thanks very much gentlemen. That is really useful.

Would the joining of No.1 pin to No.8 and No.4 to No.5 apply regardless of the number of pins a socket may have? (Please forgive my ignorance.)

[96RAF]

That only works for the 8-pin socket.

You need to pull the NEM spec for the 4, 6, 18, 21 pin sockets and see which pins to short for basic motor control and/or added lighting for them. Easily found by Google.

[Rog RJ]

@Howbi and 96RAF

Thanks very much gentlemen. That is really useful.

Would the joining of No.1 pin to No.8 and No.4 to No.5 apply regardless of the number of pins a socket may have? (Please forgive my ignorance.)

 

 

It only applies to 8 pin sockets and decoders. Different sockets need different numbered pins to be connected together.

 

 

[ModelerXYZ]

To unconvert a loco, chop off the decoder, and solder the Red wire to the orange, and the black wire to the grey wire. This will remove the decoder and the wires will be connected in the right place.

Or solder a wire from the pickups each side to the respective side of the motor. Check where to solder first.

I converted and unconverted Thomas the tank engine once.

XYZ

[Potterton]

Thanks. Do the colours referred to apply to all decoders regardless of manufacturer?

[ModelerXYZ]

They should- Its a DCC standard set by the National Model Railway Association.

[Fishmanoz]

It would be much neater if you first unsoldered the decoder, then connected the pickup wires from each side to the motor connection on the same side, rather than joining the ends of the decoder wires to each other. The only difference is leaving those decoder wire ends out to make for a better job.

[Potterton]

Thanks for all the replies and advice.