Few questions relating to the (not so) new HM7000 system (I'm very new to modelling)

[Alexander-367489]

1) Can I use non Hornby locomotives and will it still recognise them?

2) Is it possible to somehow wire the decoder to the PCB of a non DCC loco?

3) Just to make sure, is the burning out issue that Sam's Trains mentioned widespread, or is it so rare that I shouldn't be even thinking about it?

Thanks in advance

Mod note - your title amended to remove the profanity that got past the naughty word filter

[SteveM6]

1) yes but you may find that you will need to do the very simple autocalibrate process to tune the decoder to the motor. There may be figment challenges with some locos.

2) yes, just like any other decoder but if it is not DCC ready it suggests an older loco so I recommend conducting a stall test to confirm the loco current draw is within the decoder tolerances.

3) Sam’s problem was self inflicted - he did not read the instructions nor did he use an approved power supply. He is an idiot.

[96RAF]

1. When the HM7040 dongle is released you will be able to control regular DCC decoders from the app. Normal decoders do not have Bluetooth so the app would have no way of talking to them otherwise than via the dongle. Fitting an HM7K decoder to any make loco is possible and it is the decoder that is recognised not the loco.
2. You can hardwire an 8-pin HM7K decoder the same as you can any other decoder by cutting off the plug. Hard wiring next 18 and 21 pin decoders is harder but no different from their normal equivalents.
3. Your naughty word described Sam to a T. He didn’t read the clear instructions, used the wrong power supply and by his own stupidity burnt out his decoder. No decoder has been reported as burnt out by anyone using the correct recommended power supply.

Steve beat me to it.

[P-Henny]

Q2 - Wiring decoders to a non-DCC Ready loco is common-place. But you must understand the internals of some of these older locos that were designed prior to more recent designs.

Many of them used the chassis of the loco itself to provide the electrical path from one rail of the track to the equivalent side of the motor. Some even older locos had a split chassis design where the chassis was split into two insulated from each other halves so that the chassis could be used to provide the electrical path to both sides of the motor. Some locos (steam) used the loco for one track rail pick-up and the tender wheels for the other track rail with an electrical connection between loco & tender. Then there are types of 'Ringfield' motors that look similar but have different electrical pick-up arrangements.

All of these types of older designs have to be understood and identified so that an appropriate modification and decoder wiring strategy can be applied.

In essence the decoder has to be inserted into both electrical paths between wheels and motor. This, of course, means that the factory designed path has to identified and be broken somewhere.

In all cases of older locos, the motors tended to draw far more current than modern loco designs. Thus performing a 'stall test' on DC should be a pre-requisite that is done prior to fitting a decoder, so a decoder with an appropriate decoder current rating can be sourced.

Also be aware that an old loco that is not a 100% reliable smooth runner on Analogue DC will almost certainly not run reliably on DCC. DCC is far less tolerant of electrical track and pick-up conditions.

Look in the 'General Discussion' forum pinned sticky 'Useful Links' for a link that tells you how to perform a 'stall test'. The same pinned sticky thread provides links for installing decoders for 'Ringfield Motors' and also how to wire up decoders.

It is strongly recommended when 'hard wiring' a decoder into a non-DCC Ready loco that a DIY socket is wired in to allow the decoder to be plugged in and changed. Hard wiring without a socket can be a false economy and isn't really that much of a time saver, particularly if things don't go to plan and faults need to be diagnosed. The most typical socket used for DIY installation is the 8 Pin socket as these are readily available on ebay pre-terminated with wire tails to aid installation and 8 Pin decoders have been around for some time and easier to DIY wire up compared to more exotic decoder socket varieties such as the 18 and 21 pin types.

If the age of your loco(s) pre-date being 'DCC Ready' but have a more modern PCB board internally, then these will be relatively easy to convert to DCC, but a DIY fitted decoder socket is still highly recommended.

Installing a decoder really isn't 'rocket science' as long as you understand how the current gets from the wheels to the motor and where in the loco those electrical paths can be broken to isolate the wheels from the motor, therefore a Multimeter is a crucial tool to have in the toolbox if you are going to 'hard wire' a loco successfully with a decoder.

[Fishmanoz]

Note HM7000 decoders are rated as 1 Amp max continuous current. So if the result of your stall test is more than that, it would be very unwise to try using one.

RAF says hard wiring Next 18 and 21-pin decoders is harder. This is because the connectors mount directly onto the decoder PCB, there is no wiring harness. So hard wiring involves soldering to the decoder PCB having first identified where to do it, then actually doing it correctly without damaging the decoder.

Edit - first line edited as per Brew Man, thanks.

[Brew Man]

@Fishy

Slight amendment to your post. TXS decoders are rated at 1A continuous and 1.5A peak. Makes them a little beefier than 1A max.

EDIT: I see that the Next 18 Sound version is rated at 500mA continuous and 1A peak, but interestingly the non-sound version is 1A and 1.5A peak.

[96RAF]

Next 18 is limited by the current handling of the plug/socket which is why the track feed and motor circuits are doubled up. Explained in the NMRA spec for the device.

[ColinB]

If you want to wire to a 21 pin decoder from scratch, New Modellers actually have the very own circuit board that Hornby use as a spare part. The big advantage of 21 pin for a diesel is you can add extra lighting functions, you can also permanently wire the speaker which means you have less dangling wires to worry about. Really easy to wire to, 4 pads plus if you want to two for the speaker and two screw fixing. Alternatively a guy on EBay does a similar part not so good as the Hornby one but cheaper.

[Brew Man]

Next 18 is limited by the current handling of the plug/socket which is why the track feed and motor circuits are doubled up. Explained in the NMRA spec for the device.

 

 

So why is the non-sound version up to full spec?