Hornby R3897 OO Scale BR Ruston & Hornsby 88Ds 0-4-0 No. 20 - Era 7 Decoder

[Aussie Fred]

I am looking  at getting a Ruston & Hornsby loco and of course a suitable decoder. I notice there is the Hornby R7150 standard 6 pin decoder and a Soundtraxx 851001 MC1Z102P6 DCC Mobile Decoder, 6-Pin Plug which is A$20 cheaper (A$65 compared to A$45).   Does anyone have any experience with the soundtraxx decoder. I am also concerned that the latter has fixed 6 pins, whereas the Hornby has a harness which might fit better.

[Brew Man]

Train-O-Matic also do a 6 pin with harness. I think they are cheaper but I can't remember by how much.

[Aussie Fred]

I now have my Ruston & Hornsby 88Ds and the recommended decoder which is R7150 and there is my problem. They are both 6 pin and while 1. is clearly marked on the decoder, there is nothing on the loco or blank, ( have studied them under a microscope and there is nothing there).      The six pins on the decoder are  1. Brown 2. Grey 3. Red 4. Black 5.White 6. Yellow    on the motor it is  1. Grey 2. Brown 3. Black 4. Red with 5. and 6. no wires attached.  Can someone please explain?

Edited May 8 by Aussie Fred
Spelling error

[Fishmanoz]

Check out Brian Lambert in the useful links in the General forum and you’ll find all the standard plug/socket arrangements in his DCC pages, including 6-pin.

I think you’ll find what you’ve said is brown is in fact orange, then red and black are the pickups and orange and grey the motor connections. White and yellow are forward/reverse lights with the common generated in the loco PCB, if you had lights which you clearly don’t. 

When you insert the correct way around, you will get red/black to black/red and orange/grey to grey/orange.

[Aussie Fred]

Done, works OK on programming track, thank you Fishy. I was a bit panicky, because I found early thread which said the R7150 wasn't suitable for the 88Ds, but that Hornby were working on it, hopefully it will work OK when I put it on the main track.

[Aussie Fred]

Run my 88ds on the main track and worked like a rocket at full speed and crawl was exceptional. However (there is always a However or a But) does not move at all in reverse. I know it was a tight squeeze putting it back together and wondering if a wire might have come loose -any other thoughts before I pull it apart again.

Edited May 14 by Aussie Fred
Spelling error

[ColinB]

On 14/05/2024 at 09:18, Aussie Fred said:

Run my 88ds on the main track and worked like a rocket at full speed and crawl was exceptional. However (there is always a However or a But) does not move at all in reverse. I know it was a tight squeeze putting it back together and wondering if a wire might have come loose -any other thoughts before I pull it apart again.

I hate to say it but forwards or backwards uses the same wires it is only lights if fitted that are separate wires. It is either a mechanical issue, like a wire jammed in the mechanism or possibly a fault with the decoder. If you have an issue in the future fitting the decoder, Zimo make a MX617 that is incredibly small that will source 0.8 amp.

Edited May 15 by ColinB

[96RAF]

The simple way to prove if half the decoder motor drive H-Bridge has failed is to plug in an 8 pin decoder the wrong way round. If failed the loco will only drive the other way to before. Unfortunately reversing a 6-pin decoder simply means it will not work.

[Aussie Fred]

Supplier just sent me a free return postage ticket to return the decoder. Might look for a Zimo, but have to source it from UK