Older Hornby/Lima locomotives

[JB59]

I have a selection of old Hornby and Lima diesels which I wish to convert to DCC sound. I have just had an old Lima class 40 converted which starts up fine but as soon as I try to move it the power to the track trips. The shop I had it done said it may need a stay alive as the older motors draw more current than newer models. Will a stay alive solve the problem ? My dilemma is - is it worth spending money converting these old locos ? Can newer motors be fitted to older locos ? Is this a common problem ? Any comments appreciated before I waste my money ! Thanks.

[Chrissaf]

I doubt very much that a 'stay alive' will help with your controller tripping.

Sounds like the Shop trying to fob you off. Now if the issue was poor electrical pickups and the loco was stopping due to loss of pick up power, but the controller was NOT tripping, then in that situation a 'stay alive' could be a helpful suggestion.

If the Shop thought process was along the line of a charged up 'stay alive' providing a current boost to overcome an initial motor start up surge current requirement, then that would still be an indicator that the current 'power supply' power output was being stressed, in which case a power supply upgrade mentioned below would still be the most optimum solution. But in general, a 1 amp power supply should be more than adequate for a single older loco.

You haven't given any indication as to what controller you are using and what other DCC Accessories you are using with it.

For example, if you were using a Select [or eLink] controller with a 1 amp power supply and you were also using the outputs of the Select [both DCC Track & AUX] for both locos and other things, then in that situation an older loco that is drawing more current could potentially trip the controller.

In principle, older locos do draw more current than modern rolling stock. Many members on this forum run older DCC converted locos on their layouts, so that proves that it is doable.

As long as there are no faults with the locos or decoder installations, then if you are using a 1 amp power supply with your controller then an upgrade to a 4 amp power supply can not do anything but help.

With regard changing old motors for new ones, well that depends on the old motor. It is possible with appropriate skill to upgrade some 'Ringfield' type motors to a CD type can motor. But other types of old motors are invariably heavily integrated into the loco chassis and conversion to modern motors just isn't really practicable.

[JB59]

Thanks Chris. I use a Hornby Select, no accessories, it solely powers the track. Not having an electrical mind, how would you upgrade to a 4 amp supply ?

Many thanks, Jeff.

[JB59]

Just googled it, I presume this is what I would need ?

Hornby P9300 Digital 15 V 4 Amp Transformer.

[Fishmanoz]

I’ll let someone else give you the detail on the 4 Amp supply which replaces the 1 Amp unit that plugs into the wall socket and connects to the Select (Oops, you found the correct one while I was typing).

There is no reason in principle why you can’t convert your older locos to DCC with or without sound. The issue is older motors (Ringfield or X03/X04) draw more current than modern motors, particularly so when not in good condition, weak magnets usually the problem (they can be remagnetized).

Current draw will not be a problem if the decoder can handle it, meaning usually a decoder that can handle 1 Amp continuously. That precludes using Hornby TTS which are limited to half that, 500 mA. If your model shop has fitted TTS, that is a second reason, along with the erroneous stay-alive comment, they may be short on knowledge.

That the loco is tripping the 1 Amp Select means it must be drawing at least around 1 Amp. This means the motor is not in good condition or is faulty - possible strike 3 against your model shop for not finding or pointing this out. They should not draw this much.

Let us know what type of decoder is fitted? If it happens to be TTS, then it is likely the only thing stopping it burning out from excessive current draw is the supply tripping. So tell us know what type it is before trying the 4 Amp supply.

PS. I’ve made a number of English and content edits in this post just now, so check you are reading the latest. And please use the text box at the bottom of the page and green button the reply, not the blue button in my post.

[Will Hay]

You would only need stay alive if you can't maintain clean pickups and clean track, but would be useless if the device is tripping the power.

Similarly and officially, you would only need a 4amp PSU if you're running more than three trains but having said that and before I upgraded to a 4amp [now using a Z21 controller] I had five units running on a 1amp PSU without ever tripping.

My guess is the conversion to DCC is the problem.

I converted many DC/older units to DCC when I first started.

I soon rid myself of them, there's just no comparison to the quality of the newer, DCC ready models.

EDIT.

If it's not tripping as soon as it hits the track it most likely can't be the DC > DCC conversion.

[JB59]

Thanks guys, will find out which decoder it is. As I said, the loco goes through the engine start procedure and gives the sound, it’s only when I start to move it that the power trips.

[Chrissaf]

it’s only when I start to move it that the power trips.

 

 

That is a clear indicator that the H bridge output semi-conductors on the decoder have been damaged. This is guaranteed to happen if there is any electrical connection still present between the DCC track power wiring and the motor wires. This, in essence, shorts the decoder input to its output.

Many older locos use chassis returns for the path between wheels and motor, these are the most difficult type of older locos to convert as the motor has to be completely electrically isolated from the chassis. It is looking far more like whoever performed the conversion didn't do it correctly or the wires mentioned above somehow touched once you got it home - as I assume the person doing the conversion tested it OK before handing it over to you.

However, that said. If the conversion was done with due diligence then steps should have been taken to ensure that wire touching couldn't happen, and that the 'stall current' draw was within the decoder spec [see further below]. Which still puts the issue in the area of responsibility of the convertor.

When the H Bridge is damaged, the damage is permanent and not repairable and would require decoder replacement in conjunction with wiring checks to prove that there are no latent wiring shorts that should not be there.

If the decoder is a Hornby TTS one, then as others have said. The TTS decoders only have a continuous motor output of 500mA [0.5A]. This does not make them suitable for converting old locos if the old loco magnets are weak. Weak magnets increase the current drawn by a motor, and can be well over 500mA. More peak surge current is drawn by a motor when starting from a standstill.

Excess current draw can also damage the decoder H Bridge in the same way that a wiring short described above would. Again, an experienced decoder installer should [would] have performed a 'stall test' of the motor before fitting a decoder to confirm whether the magnets were in good condition and that the maximum current draw was within the specification of the decoder. It is recommended that old locos are fitted with decoders that have at least 1 amp as the continuous current rating. No current Hornby decoder meets this specification, but other Hornby decoders are in the pipeline which may.

Here are a couple of links that assist understanding the points raised above.

Brian Lambert's 'Stall Test' guide

In the 'Useful Links' sticky thread at the top of the 'General Discussion' forum. There is a link to 'Scalespeed'. This company provide a motor magnet re-magnetisation service [motor needs removal before sending off].

If it is assumed that the decoder installer performed a successful test of the decoder installation before handing it over, and the issue is indeed down to excess weak magnet current draw exceeding 500mA, then it is plausible to assume that the installers test only weakened the H Bridge but did not destroy it. Then your first use of the loco at home finished it off.

[96RAF]

You haven’t given us details of the trip mechanism you are seeing from your Select.

The 1-amp supply self protects against overload or short by browning out, i.e. it drops its output voltage which causes the Select to constantly reboot with the screen showing any manner of broken characters, most typical being the first number fading in and out.

When a 4-amp supply is used self protection falls upon the Select. On older firmware revisions (1.0-1.5) you will see OL (overload), newer versions (1.6/2.0) will show EO (emergy off which kills all track power) and is normally indicative of a short.

You may also see ES (emergy stop) which is a manual operation by the Stop button. This stops all locos but keeps the track live.

[Will Hay]

Just googled it, I presume this is what I would need ?

Hornby P9300 Digital 15 V 4 Amp Transformer.

 

 

A Hornby C7024 PSU is also suitable, something I used for a year before upgrading to a different brand of controller.

Unless money is no object, I'd not recommend spending the rrp of nearly £60.00 for the P9300.

[96RAF]

C7024 was the Scalextric version of the Hornby power brick. Same thing different part number. Now where have we seen that before.

[ColinB]

I converted a lot of my earlier Hornby and Lima locos, so I know quite a lot about doing it. The reason the guy that converted them said that you might need "stay alive" is generally on these old locos if it is a loco with tender, the loco picks up one supply and the tender the other. Similarly with a diesel, one bogie picks up one side of the supply (ie) the power on one rail and the other bogie picks it up from the other side or other rail. So when you convert them it is a good idea to put in extra pickups so it picks up power from both sides of the track. A model shop is probably not going to do this because it would cost too much. Additionally old Hornby and Lima locos generally have rubber traction tyres so even if you add pickups to these wheels it doesn't make much difference as rubber is a brilliant insulator. So the model shop probably suggested "stay alive" as if the loco goes over a bad piece of track or insulated frogs on points it will lose power, stay alive might help. The other thing to consider is the decoder choice, these motors draw about 0.8 amps when the motors stall, so when I was fitting them I found the only decoders that seemed to work reliably were the Zimo ones. Hattons, DCC Concepts, Gaugemaster and Hornby ones I successfully managed to blow up. On paper, bar the Hornby one (0.5 maximum current), they should have all worked but if the loco stalled then I got the familiar burning smell and failure. So generally I used a Zimo decoder with the YouChoos "stay alive".

As to whether it is worth spending the money, I did it with mine although I eventually sold most of them or upgraded the chassis, they will never go as well as a new one. In my case it was just the price of the parts, but if you are paying a model shop to do it, it might be worth selling them them and using the money towards a newer type. That is entirely your choice, some of the locos it is possible to put in a newer chassis, I eventually did this with most of mine surprisingly most tender driven Hornby bodies fit the newer chassis.

[JB59]

The decoder is a Loksound, not TTS and my select power supply is R9300W which looks like a 4 amp one already.

[Chrissaf]

All my decoders are Loksound and I use a P9300 4 amp power supply with my Elite controller without issue. Albeit my locos are all new 'DCC Ready / DCC Fitted' and not old loco conversions.

But that said, the H Bridge damage I documented in my previous reply is still a potential fit with your documented observations.

Use a multimeter to measure resistance and look to see if there are any low resistance measurements between the wheels and the motor. The decoder should provide a high resistance measurement between those measurement points, and any low resistance measurement indicates that the motor has not been correctly isolated from the wheels as part of the decoder installation.

Multimeters can be purchased cheaply off ebay for less than £8 delivered.

[ColinB]

Reading your post again, "stay alive" won't fix the short. Assuming you haven't blown up the decoder, which you can usually tell by the electrical burning smell, it is probably something simple like a pickup shorting against the body. I assume the model shop didn't use a socket, if they did it might be worth putting a DC blanking plate in to see if it runs on DC. It could be that your decoder could not handle the motor current, but if this happens you normally smell it burning, unless your decoder has decent overload protection. Is the loco on a straight or a bend when this happens. Did the model shop put in a socket?

[JB59]

Thanks again guys. The loco is on a straight when I start it. After attempting to move, the power trips and shows as error message. On resetting the Elite, the loco can be restarted and gives sound but again trips when a move is attempted. No smells of burning.

[Jim-R855]

I'm new here, but exclusively have older models that I have been converting and gathering some experience of the pitfalls.

Try unplugging the decoder, then set the model down off the tracks with multimeter on left and right wheels and it should indicate infinte resistance. Now try rocking the model in different directions and pushing down on it etc. If at any point the meter gives a reading other than infinite you have a short, but one which only happens when the loco is moving.

I have some older models with metal chassis where the isolated wheels can touch the chassis if the model rocks or bounces on the track. Everything else is properly isolated and there are no shorts when stationary. You need to find the short paths and isolate them - I've been using kapton tape but I have no idea how long it will stay stuck.

Note that Chrissaf sees a correlation between symptoms and H bridge damage, so it may already be too late for that decoder, but do carefully check and eliminate temporary shorts before trying another!

[Fishmanoz]

Wow JB, you have certainly received a wealth of information in reply, from the older hands around here and some of the newer. And while different words have been used, most of it is saying much the same, so I think you have your answer.

If I can add/summarise a couple of things for you:

• easy to tell the difference between the 1Amp and 9300 4 Amp - with the 1 Amp, it plugs directly into the wall socket and the only cable from it is to the controller. The 9300 has a cable at one end of the “brick” as Rob puts it going to the wall socket and a separate cable to the controller at the other end
• i would be having very strong words with your model shop. It seems to me they have neither tested properly the loco before installation or the decoder after installation. I would be demanding they either fix it to your satisfaction or give you your money back. That’s an expensive decoder which should have been up to the task and you should expect better from them.

[96RAF]

@JB

I see a change of controller. Initially you were talking about ‘my Select power supply is’ now we are seeing an ‘Error message on my Elite’.

Can you please clarify which one you are using or is it case of the fault is there with either.

[ColinB]

If the loco gives sound then I doubt the H bridge has died, generally when the H bridge dies it takes virtually everything with it. To me it sounds like something wrong with the loco contacts. If the controller trips out that means at least you are shorting 1 amp of power or if you are using the Elite 4 amps, the decoder would generally blow up on that. What loco is this?

[JB59]

It’s a Lima Class 40

[Fishmanoz]

Hi JB, good pickup by Colin here. You certainly did tell us Select originally, now you’ve said Elite. That explains the 4 Amp supply as Elite comes standard with it, unlike the Select.

Again, my recommendation is the shop conversion has failed and return it to them.

[ColinB]

I have just been looking at a Lima I converted. Unlike the Hornby, it is really easy to put at extra pickup on the dummy bogie. The model shop hasn't put the wheels back in wrong on the dummy bogie by chance. If one of them had dirty wheels it is possible as the loco moves it finds a part which conducts and hey presto a short. So one is in the right way round but the other one is wrong. Sounds like a return to the model shop. I had exactly this sort of issue on a Hornby loco with tender pickups if you get the tender pickups wired opposite to the loco ones.

[LMSFan72]

Is it converted with a socket or hard-wired? If a socket I would remove the decoder, fit a blank, and try a 9V battery on the wheels to see if the motor will turn on DC.

Also, have you tried resetting the decoder?

[JB59]

Thanks for all the help guys, I have returned the loco to the shop for (hopefully) remedial work.