Bachmann "C" Clss conversion

[JFS]

I am in the process of converting a Bachmann "C" Class to P4 using the Brassmaster Easichass (quite nice) and Exactoscale wheels (VERY nice). All is going well but I have reached the point were my knowledge and experience has run out - connecting the motor...

Here is a photo of the Bachmann motor:-

Bachmann motor].jpg

Why on earth are three capacitors and two resistors necessary? This seems a long way over the top compared with a single "radio suppression" capacitor I remember from my Triang days and so I have a sneaking suspicion that the phrase "DCC ready" emblazoned on the box might be at play here.

My instinct would be to just hack the lot off and connect the pickups to the motor brush gear, but just before I do that, I thought I might ask some questions;-

1. Why is this lot provided in the first place?
2. What would be the consequences of (a) leaving it all in place (b) hacking it all off.
... given that my layout is DC using a mixture of 3 Pentrollers and a single Pictroller, and that I value the benefits of the clever feedback electronics which these controllers confer.

Best wishes,

[grovenor-2685]

What look like resistors are actually inductor coils, the whole setup of capacitors and inductors is there to block high frequencies generated from the commutation getting back into the rails and being radiated out froom there. The regulations in respect of Electromagnetic Interference are rather stricter than they used to be and fitting these items is required in order to sell the locos on the market. Using DC there should be no need to disturb the arrangement. For those using DCC, where the decoders use high frequency feedback the capacitors often interfere with the control and need to be removed. In the DCC case the decoder itself isolates the motor from the track so the suppression feature is redundant anyway.

If you do find that control from your pentrollers is rough then you can try snipping the capacitors off. They are legally required to be put on by the manufacturer but there is no legal obligation on you to keep them so long as removing them does not result in complaints from your neighbours.
Regards
Keith

[JFS]

Many thanks for this Keith - most helpful. I might just do a "with and without" trial.

If you do find that control from your pentrollers is rough then you can try snipping the capacitors off.
Keith

Well that is interesting - I have a Bachmann 4MT tank which runs fabulously well at speeds up to about 40 mph and like a bag of chains thereafter. Not an issue on my layout, but I might just try your remedy...

I have quite a powerful FM antenna on the roof about 2.5m from the layout and have never heard any interference from any of the locos (but then nothing exceeds 20mph at Minories!) and surely no one uses AM radio any more ... ?

Many thanks and best wishes,

[grovenor-2685]

Well that is interesting - I have a Bachmann 4MT tank which runs fabulously well at speeds up to about 40 mph and like a bag of chains thereafter. Not an issue on my layout, but I might just try your remedy...

Nb. The "remedy" might help with back emf/feedback controllers, its not going to do anything with a standard DC controller.
Regards
Keith

[JFS]

Thanks Keith.

I got it together and have given it a run (with the gubbins intact). Apart from some rather bad cogging at its absolute slowest it runs fine with the Pentroller on the "iron" setting. On the other settings it is very erratic which is probably to be expected.

Now by way of experiment, I should take the bolt croppers to the capacitors and see what difference it makes...

It seems strange that the cogging is much worse than the 4MT - does anyone know if Bachmann have down graded their motors of late? Would it really increase the cost by that much to provide a skew-wound motor?

Cheers,

[Philip Hall]

From what Hornby were saying a couple of years back, yes, it did cost a fair amount more for a better motor. I can't see it myself, but I think that the cost saving that came with 'Design Clever' (now, it seems, a philosophy consigned to the bin, thank goodness) meant that three pole motors were fitted in some models. Strange that on some engines you noticed the difference, some you didn't. Now with the new releases we have, I think, the remnants of cost cutting and the first signs of renewed finesse; the new Hall has (so the website says) a three pole motor, but the new J15 a five pole with two flywheels!

I have had many Bachmann engines which have been smooth as silk and others like a bag of nails, such is life. I find the Pentroller on its 'iron' setting is a fair bit choosy when it comes to RTR models. I usually use an old AMR with the feedback cut back a bit, and am about to experiment with a cream panel Gaugemaster and a Modelex, the latter recommended by Roy Jackson. Recent trials of a Hornby King Arthur, converted to P4, on a black panel Gaugemaster (fitted to the layout on which it is to run) have been atrocious, the motor clearly doesn't like it at all. Either that or I've done something very wrong. It will be back in shops for investigation. All these have been handhelds by the way.

Philip

[JFS]

Many thanks for that Philip. I might have been a bit spoilt by the 4MT - it ran pretty well from the off. Having said that, when I first converted it, my Pentroller being packed away, I tried it with a (very basic) Guagemaster controller, and it was awful - limping badly and unable to hold any kind of steady running. When I got the Pentroller out of hiding, I remembered exactly why I like them so much! The Guagemaster is now in the process of being donated to NAG! But I agree that the Pentroller is fussy and it would not do for any high speed exploits with the 4MT

The "C" Class actually runs quite nicely - apart from the cogging. If I disengage the worm, with the motor running light, I can see it stepping from one pole to the next every quarter of a second or so.

It is not difficult to see why these things can be so different in their unconverted state - with slop and excessive clearances, wobbly wheels, poor quartering etc, but after converting this thing (and with Exactoscale wheels no less!) I know for a fact that it is spot on - which only leaves the motor and gears!

Of course, re-reading the "instructions", it does say to "run it in" for half an hour - which needless to say I have not done, so there may well be a bit of roughness in the bearings or the brush gear to rub off. What did that man say - if all else fails...

I am a bit limited in choice of controllers as my fleet of GW locos is all Portescap and I don't intend that my SR fleet will be converted RTR forever, so the "proper" fleet will one day have coreless motors.

Cheers,

[Philip Hall]

Howard, a few further suggestions...

I believe there are two distinct Gaugemaster controllers, so if you have a black one rather than a cream one that might be one reason. Secondly I have an old Gaugemaster kit controller and that is a bit variable as well. I have, though, a customer who uses the cream handheld with no trouble on a variety of motors.

If the motor is cogging when running light, I suspect there's not a lot to be done with it. It might be possible to swap the motor for a similar sized Mashima - you might have a bit of fun with the bore size of the worm gear which might not be a standard size, so a bit of bushing or opening out might be required. It would probably solve the problem, though.

I would also try a different controller; Roy suggested Modelex to me as he has many Portescaps and all sorts of others, RTR conversions, Bachmann and Hornby. I haven't tried it yet, and won't be able to for a few weeks, but send me a pm to remind me sometime and I will post the results.

As you say, tightening up the clearances all round so everything is spot on (which it isn't always on some Bachmann chassis) removes all the production tolerances ie slop, and with straight conversions I have found that taking out too much is not always a good idea. I aim to leave a bit in there but not to excess, you understand. In your case, with rods, chassis and wheels right on the money, a bit of running in might help the gears bed down, and maybe the motor.

Good luck, do let us know how you get on. Not least because I might have one or two of these to do myself!

Philip

[JFS]

Again, many thanks Philip.

The Guagemaster controller I was using was a cream-paneled Series U. Not very impressive...

I am convinced that the motor is a crock of cxxp. Even off a 9v battery it runs irregularly and sometimes noisily: off both the Pentroller and the Pictroller it is no better and there is also occasional sparking at the commutator which is never good. Even after "running in" for several hours it still cogs. Not helping is the fact that there is about 0.8mm end float, though that could be overcome. Of course, what I do not know is if I have a one-off duck-egg or if they are all like this, and the problem is simply that my expectations are too high!

Anyway, it will "do for now" until I can get a better motor. The maximum width would be 14mm and the max length (frustratingly) 23.5mm, shaft diameter 1.5mm, so the Mashima 1220 might do, but given that my natural loathing of iron cored motors has not been in any way tempered by this experience, I have sent an email to EMS to see what price a Faulhaber 1319: the somewhat more sophisticated Maxon RE 1320 is CHF67 +VAT - makes the wheels look cheap at least!

I'll let you know what transpires...

Best wishes,

[Philip Hall]

Howard,

My feeling about Portescaps is the same as yours about conventional motors! The 1220 is a fine motor, as is the 1420. I do suspect you have a rogue; Bachmann are very helpful with spares by email so that might be another route and possibly cheaper and simpler to start with.

Notwithstanding that these problems could possibly be overcome or alleviated by using DCC, it is interesting that these discussions are still very relevant for those amongst who prefer the old fashioned ways. I for one am relieved that in my continued choice of analogue I am not alone!

Keep us posted.

Philip

[JFS]

Philip,

Many thanks for the tip on Bachmann spares - I am on that case. I will also give the 1220 a go - just by way of overcoming my prejudice!!

Howard,

My feeling about Portescaps is the same as yours about conventional motors!

Philip

I wonder why you feel so badly about them?

Maybe you don't distinguish between "Portescaps" and and the Faulhaber motors they contained? The original Portescap motor-gearbox combinations run wonderfully smoothly and quietly, newer ones are absolutely dreadful - but it is the gearbox - specifically the state of the delrin crown and pinion which makes the difference - it seems like the moulds wore over the years and never got replaced. But the Faulhaber motors are all consistently good! So I am certainly not in the camp of paying ebay prices just because it says Portescap on the bottle - though if I knew it were 30 years old...

A couple of years ago, Tony Wilkins and I had a slow race with two of our locos - both Portescap fitted - round the Pentroller-equipped NL group test track which was then on loan to NAG. After about half an hour and less than a quarter of a circuit completed by both locos, we got bored... That is controllable performance! Which is not to say that the same cannot be achieved by other means - just that the combination of coreless motor and a high-frequency feedback controller seems perfect for our needs! And the Maxon RE 1320 is 1.6Watts - if all else fails, I could use it for hauling the baseboards up into the loft

I am by no means convinced that DCC can ever overcome the limitations of a poor motor - any more than a powerful motor is a substitute for well fitting, accurate and free running mechanicals - but I am sure we about to get inundated by people telling us otherwise!!

Best wishes,

[williambarter]

A bit of a side issue but much as I had been taught the theory behind regeneration I had never quite believed it. Not that is, until I placed two locos with Portescap motors on a test track, pushed one (which you can do because it drives through spur gears rather than a worm), and saw the other move. Very weird, until I realised what was happening.

On topic, as I am working my way through one of these myself, the thing that has given me most trouble was the loco brake-rodding, which if assembled as per instructions seems to end up linking the main frames to the keep-plate, which doesn't make it easy to remove the keep plate. My solution was to lightly solder the brake rodding to the inside of the springs on the frame etch, and just leave the rear ends free, having set their location with a bit of wire through the brackets before soldering.

The tender brake-gear looks lovely in the photos but is a nightmare to assemble, and unless done perfectly the clearance for P4 wheels seems minimal. Next time I think I would not bother with the inner brake-rods (which can hardly be seen, in fact I did not realise such things existed previously) but solder the inner and outer rods back to make to make something a bit more robust and attach then to the inside face of the plastic frame moulding

William

[Albert Hall]

What look like resistors are actually inductor coils, the whole setup of capacitors and inductors is there to block high frequencies generated from the commutation getting back into the rails and being radiated out froom there. The regulations in respect of Electromagnetic Interference are rather stricter than they used to be and fitting these items is required in order to sell the locos on the market. Using DC there should be no need to disturb the arrangement.

They are legally required to be put on by the manufacturer but there is no legal obligation on you to keep them so long as removing them does not result in complaints from your neighbours.

Going back to this issue, is it necessary to fit any sort of suppression to say a standard Mashima motor in a kit built loco being controlled by DC? If none is fitted and neighbours do complain about interference, can the authorities turn up and confiscate the transmission system i.e. your layout?

[Alan Turner]

Theoretically yes!

There is a big issue at the moment with Internet over mains cables.

regards

Alan

[nigelcliffe]

Going back to this issue, is it necessary to fit any sort of suppression to say a standard Mashima motor in a kit built loco being controlled by DC? If none is fitted and neighbours do complain about interference, can the authorities turn up and confiscate the transmission system i.e. your layout?

No, its not necessary to fit any form of suppressor, and fitting them can only make effective control more difficult.

Maybe theoretically the authorities could intervene and burn your layout. AFAIK, they haven't *ever* confiscated a layout (or loco), they won't do it, you don't have the test equipment to show that you've correctly fitted effective suppressors, a neighbour with a problem almost certainly could fix it with a proper aerial lead to their TV rather than a bit of wet string (and I doubt it ever manifests with digital TV rather than 405 line TV, let alone 625 line), etc.. So the issue can be safely ignored.


- Nigel

[Albert Hall]

I was wondering if modern motors had any form of suppression inbuilt but I can see the logic regarding the comment about digital TV. I seem to recall a similar discussion in probably the Railway Modeller many years back in the era of the Triang X04 motor and long before digital TV came about. I think I am correct in saying that analogue TV is now extinct in the UK but what about radio?

[nigelcliffe]

I was wondering if modern motors had any form of suppression inbuilt but I can see the logic regarding the comment about digital TV. I seem to recall a similar discussion in probably the Railway Modeller many years back in the era of the Triang X04 motor and long before digital TV came about. I think I am correct in saying that analogue TV is now extinct in the UK but what about radio?

No suppression built in. Why would a motor maker add something which not necessary for the sale of their product ?

If you want to fit suppressors, go ahead. But, its not necessary. I doubt anyone can be found who has been formally approached by the authorities in the last two decades over radio interference from a model railway. There are far worse sources of radio interference all over the country which go completely unchecked.


Analogue TV ended several years ago in the UK. Analogue radio remains, and is likely to remain indefinitely.


- Nigel