Advice needed on fitting decoder in Hornby 8F

QUOTE (Robert Stokes @ 24 Jan 2008, 00:13) <{POST_SNAPBACK}>Hello and I hope that someone will be able to help me complete this task.

I bought a DCC ready Hornby 8F into which I want to fit a Bachmann three function back EMF decoder. It is too large to go in by just plugging into the DCC ready socket so I have a mind to remove the socket and just solder the relevant wires.
There are four wires going into the socket, two black and two blue. Can anyone tell me which pair come from the pick-ups and which pair go to the motor? Also just behind the socket is an orange capacitor with its leads going into a little black box about 5mm square and 2 or 3mm thick. Should I remove the capacitor? What is the little black box and should I remove that as well?

I suppose it might be better to buy a smaller decoder and fit the Bachmann one in another engine but I'd still like to know how to do the job in the first way either for this or a subsequent engine.

Someone recently mentioned in another thread that Bromsgrove Models were doing five small TCS decoders for £49 but I can only find them offered at £65. Have I missed something?

Thanks for any help, Robert.

***Robert, Hornby aren't consistent enough to give a "formula" for interpreting their wiring by colour.

Its always best to check with a meter, and VERY important to have loco and tender on the rails and connected so U dont reverse loco and tender connections and create a short.....

ALSO check the tender pickups and tender wheel back to backs - pickups often need adjustment and tender wheels are always too close together....

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to business:

Look at the 8 pin socket.

looking down at the holes the pins go into...
top left should be decoder orange
top right should be decoder red
bottom left should be decoder black
bottom right should be decoder Gray.

To confirm this take out the blanking plug & put loco and tender on a bit of track with the body off.

set your meter to ohms - range k ohms or below if U have choice.

put one probe on the top right and see if when you put the other probe on either rail, it shows continuity (becomes zero ohms) It hould do this on the right rail (right as in standing in the loco cab looking forwards)

Then put the same probe on the bottom left and see if the OTHER rail shows continuity. This will confirm that top right and bottom left are correctly oriented... they should be, I just chipped one and they were....

NOW you know which wires to use, take them off the socket one at a time and mark them so U can get it right.

Capacitor. As U are hard wiring dump the hornby harness between socket and decoder totally...... wire orange and gray directly to the motor terminals

Richard
DCCconcepts

PS: the higher price U see on the Bromsgrove site is probably with 8 pin plug, the lower one without..... The MC2 is perfect in the 8F - a doddle to fit, and it runs like a dream with one installed.

Yesterday I fitted a bachmann jinty, H princess, H duchess and H black five with MC-2 - all had zero difficulty, all have their capacitors removed, all creep at speed step one with NO need for adjustment- perfect!

Richard's right- I put a MC2 in my 8F and it works really well. The bach decoder wouldnt fit anywhere due to size. I didnt have any issues with wiring and used the DCC ready plug as fitted, removed the capacitor as usualy in a DCC fit and it all worked fine.

The only issue I had was that the very fine connecting rod and piston detail was a fiddle to put back together when I (unnecessarily) undid the block that holds the pistons in place whilst attempting to find room for the bach decoder. It all went back fine but there were a few moments of worry when all that fine wire-work collapsed onto the work bench! Ther should be no need to strip to that level so avoid it if you can.

Good luck.

The TCS MC2 works a treat too........ultra-slow speed response. I use a Dynamis and have it set on 28 speed steps and it's great.

On my S+D layout I run a coal train headed by the 8F and a jinty pushing at the rear just like they used to over the mendips in consist with no worries. Mega fun!!

dave

Richard's right- I put a MC2 in my 8F and it works really well. The bach decoder wouldnt fit anywhere due to size. I didnt have any issues with wiring and used the DCC ready plug as fitted, removed the capacitor as usualy in a DCC fit and it all worked fine.

The only issue I had was that the very fine connecting rod and piston detail was a fiddle to put back together when I (unnecessarily) undid the block that holds the pistons in place whilst attempting to find room for the bach decoder. It all went back fine but there were a few moments of worry when all that fine wire-work collapsed onto the work bench! Ther should be no need to strip to that level so avoid it if you can.

Good luck.

The TCS MC2 works a treat too........ultra-slow speed response. I use a Dynamis and have it set on 28 speed steps and it's great.

On my S+D layout I run a coal train headed by the 8F and a jinty pushing at the rear just like they used to over the mendips in consist with no worries. Mega fun!!

dave