Developing this as a separate thread, which may be useful as others contribute their experiences and techniques....
Fitting Methods I have used =========================== (no liability accepted, and no approval sought frommanufacturers) E+OE
I'm biased, I admit, having started with Zero-1, and used it with multiple use of numbers (in 'periods of operation') with over 100 locos. I now have a LARGE bag full of removed Z1 modules, as these have ALL now been replaced by dcc decoders from ZTC or Lenz: I've lost count of how many Maccoders I've bought for steam locos. I have now converted over 150 OO/HO locos/units, and added MTS (with sound) to many LGB locos.
The newer decoders are SMALLER (for the same power) and much easier to fit - EXCEPT where the model makes it difficult to isolate one side of the supply to the motor: However, these problems can be overcome:1/ Hornby Dublo - I used the ZTC service to isolate the uninsulated brush and refit it with an insulated assembly - worthwhile for my 'heritage' stock to stop it only being left in a display cabinet.
2/ Some Hornby Ringfield mechanisms which use the length of the screw holding the silver 'brush arm', to connect through to the 'other side' of the chassis. - my examples of this are the Schools locos (on first release) and others of that period. For these I have cut away some of the brush arm, to provide room for insulation, and refitted the screw with either an insulating washer, or nylon screw.
_____ ____ [ x ] [ x ] x = screw mounting [ ] [ ] (left screw through to metal of chassis) [ ] [ ] b brush beneath [ ] [ ] Mod: (left strip) (x) __b_ _b_ (insulation () ) ___
Other versions use a wire on tag/spade to pick up or screw fitting (China)3/ Older Mainline mechanisms: white plastic motors. These I concede I have replaced with current Bachmann replacement chassis (see below for their conversion) for perfomance reasons anyway. (Except for lack of Class 4MT chassis) To convert: the metal tags from the motor terminals touching the chassis can be removed, and the job is almost done.
4/ Older Mainline chassis eg J72, (and previously used with Zero-1**) I had had to isolate these on the 'brush arms' 20+ years ago, twice, when Zero-1 changed its polarity for 'forward', and so most of these were already cut across and melted/welded into position. As with the Hornby, they relied on screw length to connect to the far side of the (live) chassis. A nylon screw of the correct size would work, or a shorter screw, providing that the chassis remains sufficently aligned with the remainder. **a section of one side of the chassis was cut away for the module5/ Current Bachmann (non dcc ready) split chassis locos: I choose to fully dismantle the chassis, and cut away the metal of the chassis which locates the 'spring' contact onto each motor terminal. I then use a sleeved connection for the decoder to the motor, to prevent the possibility of a short circuit here (remember the motor wants to rotate in its mounting - hence the need to also leave sufficient supporting metalwork)
Before (MM) (MMM) (MMM) represents chassis metal (MM)ssT (MMM) sss contact spring (MM) (MMM) T motor Terminals (MMM) Tss(MM) (MMM) (MMM) (looking from rear of chassis)
After (MMM) (MM) represents less chassis metal [T] (MMM) sss contact spring (MM) (MM) T motor Terminals (MMM) [T] (M) [ ] sleeved connection (MMM) (MM) (looking from rear of chassis) Top left and bottom right cut away3/4/5 and 2/ Power pickup from chassis blocks: It can be difficult, if not impossible to solder to the large mass of the chassis - or have a reliable tag/spade contact in a Hornby bogie.
My most recent improvement here has been to use some of the 'copper tape' supplied for the power bus distribution on the layout:
For the Hornby non-power bogie: - add piece of tape, with folded over section, and then solder wire to it. (Note that the adhesive side is 'insulating'.)
For the Mainline/Bachmann split chassis: - place separate pieces of copper tape onto either side of one (or more) of the foam adhesive pads supplied with the decoders: fold the surplus length of each over, and away from the other side before soldering to the exposed ends
sssss Cu Cu Cu Cu ssssss ssss= soldered lead (MMM) Cu Foam Cu (MMM) Cu = copper tape (MMM) Cu Foam Cu (MMM) Foam = sticky pad (MMM) Cu Foam Cu (MMM)
Foam ensures contact pressure onto the copper tape. Note that when cutting away the metal, the motor and gears are completely removed first, and all oil/ metal particles etc is cleaned off before reassembly and relubrication)
LIMA: Replace the black or bare copper wire from the Power Bogie pickup to that goes to the motor terminal (left side, usually), with the longer black wire of the decoder module (bogie pickup to decoder) and grey wire (decoder to motor terminal) Note: If completely reomoving a power bogie, that the aperture for the bogie in the chassis is assymetrical - and must allow room on one side for the gears when taking curves!!
AIRFIX: Older motors take large currents (eg 1.4A stall current on my Prairie) - this may mean a more expensive decoder, or it may mean that it is cheaper to 'upgrade' to a modern chassis, with modern wheel standards8-)
I obtained a new Dapol chassis for my Autotank for just 10ukp (In Zero-1 days, this was the only loco in which the module went in the coach behind 8-( )
I have replaced some Hornby 0-6-0T chassis with Bachmann chassis, or current 'Thomas' chassis. (I have had limited success at replacing older X03s with 'blue geared' motors - these usulally require chassi mods to fit, and you are still left with the old wheels... therefore this is being used for my Ivatt 2MT and M7s since no alternate option is available)
(Improved wheel standards is a contributing factor when deciding on the best approach to upgrading an old unit... increasingly it is cheaper to replace the whole loco with a current super detail version.