New Locos Compromised on DC to Favour DCC?

[28XX]

I'm not a fan of DCC. I have a fair collection of DC locos from the last 3 decades, but I am about to buy new. It occurs to me that, while all new production is capable of running on DC, the circuitry may be optimised for DCC, and prolonged use on DC might not be ideal. Am I just a cynic, or is this an actual problem?

[kevinlms]

I'm not a fan of DCC. I have a fair collection of DC locos from the last 3 decades, but I am about to buy new. It occurs to me that, while all new production is capable of running on DC, the circuitry may be optimised for DCC, and prolonged use on DC might not be ideal. Am I just a cynic, or is this an actual problem?

Surely if you pull out the decoder & replace with a blanking plate, the motor is now directly connected to the pick ups?

[Memphis32]

There's often a pair of inductors and a cap in there, which might affect some "DC" controllers that pulse or use feedback.

[Crosland]

If you buy DCC fitted (i.e with a decoder) then the running should be excellent, you just need to turn the controller up a bit further to power the decoder. As stated above, you can remove the decoder. [Edit] If you use a pulsed DC controller then that may confuse the decoder and cause problems. [/Edit]

 

If you buy DCC ready (i.e. a socket with a blanking plug), or remove the decoder, then you get nothing that you would not get in a DC loco.

 

The suppression components (capacitors and inductors) pre-date DCC and are present, in one form or another, in all DC locos. The pulse frequency in a DC controller is too low to be affected.

[28XX]

My controllers are basic feedback home made jobs using a discrete transistor and a power i.c. The circuit has been shown on here and is in chapter 4 of Roger Amos' book.

[stewartingram]

I admit to luddite tendencies too. Most new diesels come with lights fitted as well as provision for DCC fitting. As I positively hate working lights (too bright, especially for the green era) my 1st job is to take the body off and rip them out. I also usually remove the DCC wiring and blanking plugs at the same time, just to simplify things. If necessary I then add extra pickups. Same applies to steam locos as well.

 

Stewart

[Steamport Southport]

Pardon my ignorance but i thought the problem was with the coreless motors that are currently being favoured by some manufacturers.

 

 

 

 

Jason

[bertiedog]

There's often a pair of inductors and a cap in there, which might affect some "DC" controllers that pulse or use feedback.

Those are the suppressors and must not under any circumstances be removed, unless the DCC chip is fitted. They do not affect any known controllers except ultra high frequency types which are as rare as hens teeth. They are invisible to DC and only have a filtering effect at radio frequencies, not the pulse or feedback frequencies, which are far lower down the bands.

 

Pulse controllers work at near audio frequencies, nothing near the RF suppression filters band.

 

I have heard from many people who claim they are sure the suppressors are useless, but as I was employed by the GPO to work on radio suppression, and hold certificates/ degree in the subject, I think I should know!

 

What possibly confuses people is a new loco running in, the running may be poor at first and then settles, but it is tempting to blame the suppressors, which are usually removed towards the end of any running in, and things improve at that point, but it is not the suppressors.

 

Lawful regulations demand radio suppression to be fitted, so removing it is just not on. It so happens DCC has a filter in the circuit and the output stage of the chip will not pass RF anyway.

[Suzie]

It is usually the other way around - DCC capability (especially lighting) is compromised to be backwards compatible with simple DC directional lighting. The Blue Pullman is probably the only exception to this that I can think of where perhaps things are now starting to lean in favour of DCC.

 

If you are an analogue person then DCC decoder fitted locos can be a boon. If a loco is fitted with a good decoder you get an individually tuned feedback controller inside the loco so that you can drive the track with true DC and get better control than you ever dreamed of. If you think that the lighting is too bright you can easily adjust the brightness CVs in the decoder.

 

The raw loco fitted with a blanking plug in the decoder socket is still every bit the simple DC loco of old, and if you don't want the lighting just cut the lighting links on the blanking plug - there is no need to destroy the loco!

 

What a lot of people are probably disliking about modern locos is the RF interference suppression components which can upset some expensive analogue controllers. These are only present for the benefit of DC compatibility, DCC does not need them and they have to be removed!

[DCB]

I'm not a fan of DCC. I have a fair collection of DC locos from the last 3 decades, but I am about to buy new. It occurs to me that, while all new production is capable of running on DC, the circuitry may be optimised for DCC, and prolonged use on DC might not be ideal. Am I just a cynic, or is this an actual problem?

I think you have a point, it makes little sense for manufacturers to make mechanisms intended for small wall wart 1/4 amp DC power units and DCC bullet proof enough to cope with 4 amps worth of 21 volts AC.

Some of the motors currently used look suspiciously like those you can buy on Ebay for £1 including postage and packing, and like the ones I recover from dead computers.

As I see it the main problem is those late 80s era electronic controllers which were optimised for the direct worm drive motors. These worm drive locos are very hard to get started, the worm pushes the worm wheel sideways on initial rotation and only turns

it when all the sideplay has been taken up, at this point the loco disappears like Mr Bolt in a 100 metres final. To overcome this you need some fancy circuitry such as feedback.

When you use a layshaft or spur gearing 2000s style this "Sticktion" ceases to be a severe problem and the main advantage of Feedback controllers disappears. All my older locos have their worm wheels shimmed for minimal sideplay and most work very well on variable voltage DC with two

of my controllers being simply diodes in series with trappings to give variable voltage with a Hornby Dublo transformer providing the DC and overload trip.

I try to use 0 - 12 volts DC on my models rather than PWM and the fancy electronic controllers of the early 2000s but there is no doubt that 2010 era motors and particularly coreless ones are no match for the good old X04 when it comes to overload.

That said my brand new Wrenn 08 managed about 3 feet and burned out back circa 1987 so maybe I'm looking at the world through Brunswick Green coloured glasses.

I reckon its Feedback vs DCC not DC vs DCC which is the issue.

[davetheroad]

Those are the suppressors and must not under any circumstances be removed, unless the DCC chip is fitted. They do not affect any known controllers except ultra high frequency types which are as rare as hens teeth. They are invisible to DC and only have a filtering effect at radio frequencies, not the pulse or feedback frequencies, which are far lower down the bands.

 

Pulse controllers work at near audio frequencies, nothing near the RF suppression filters band.

 

I have heard from many people who claim they are sure the suppressors are useless, but as I was employed by the GPO to work on radio suppression, and hold certificates/ degree in the subject, I think I should know!

 

What possibly confuses people is a new loco running in, the running may be poor at first and then settles, but it is tempting to blame the suppressors, which are usually removed towards the end of any running in, and things improve at that point, but it is not the suppressors.

 

Lawful regulations demand radio suppression to be fitted, so removing it is just not on. It so happens DCC has a filter in the circuit and the output stage of the chip will not pass RF anyway.

 

I found that removing the suppression circuitry did indeed cause radio interference, in my case my transistor radio on FM had no interference but on AM there was crackling, However as this only happened if the radio was closer than 18 inches to the loco and the next nearest device is about 40 feet away (my TV) I am not going to worry about it.

[DCB]

We had trouble with a brand new Bachmann B1 which upset a neighbours TV, Just the B1, H/D castles Triang Britannias, K's 57XX, Airfix 14XX, Trix 56XX

home made unsupressed locos were fine but the damn B1 sent crackles across his screen. We cured it. He moved his aerial!

I always try to it bigger than standard ceramic caps to my DC locos in the hope of minimising interference.

[Chris M]

My exoerience is that chipped locos run slower and hotter than desirable. Replacing the manufacturers chip with a blanking plug immediately improves performance. There are some electronics on the pcb that holds the chip/blank. I know this because my Dapol class 22 had something go phutt on this board over the weekend. It does not appear to be radio suppression as there is also a separate capacitor and resistors. Anyway I removed the board and wired direct and she runs fine.

There can be no doubt that designing locos to be dcc ready adds cost that us dc types have to pay for no good reason. It also compromises chassis design as space has to be made for the chip and wiring. One of the nicest chassis I have is a Tomix one which has absolutely no provision for dcc. Nice and clean and simple design and runs oh so smoothly.

The point about lights is a good one. In the days before bright headlights you would not see any noticeable lights on a diesel during daylight. You will not see a red light on the rear of a diesel when it is pulling a train. So, for 1960s railways, no lights is more realistic than having lights unless you are modelling a night scene.

[Richard Lee]

I understand that using DCC chipped locomotives reduces the DC control options available. For instance, I find 'electronic track cleaners' useful when running my layout.  If do you run DCC chipped locomotives on a DC layout, I understand that 'electronic track cleaners' (Relco or Gaugemaster HF1 or HF2) are very bad for the DCC chips.  On the other hand, most new locomotives seem to be "DCC ready", that is DC, but with easy provision to add a DCC chip if required, so no problem. 

 

The other big worry is that I am aware of are coreless motors, which seem to work reasonably well on vanilla DC, but whose manufactures (such as DJ Models/Kernow) recommend not using 'electronic track cleaners', and certain other goodies with them.  I am not sure whether or not these are designed with the expectation that most users would convert them to DCC.

 

If a potential purchase is either chipped or a coreless motor, it puts it a bit further down my "I wouldn't mind buying it" list.  At the moment I have one locomotive that I have to turn off my HF1 for.  If I got more than a certain number it would be inconvenient to use it.

[davetheroad]

My exoerience is that chipped locos run slower and hotter than desirable. Replacing the manufacturers chip with a blanking plug immediately improves performance. There are some electronics on the pcb that holds the chip/blank. I know this because my Dapol class 22 had something go phutt on this board over the weekend. It does not appear to be radio suppression as there is also a separate capacitor and resistors. Anyway I removed the board and wired direct and she runs fine.

There can be no doubt that designing locos to be dcc ready adds cost that us dc types have to pay for no good reason. It also compromises chassis design as space has to be made for the chip and wiring. One of the nicest chassis I have is a Tomix one which has absolutely no provision for dcc. Nice and clean and simple design and runs oh so smoothly.

The point about lights is a good one. In the days before bright headlights you would not see any noticeable lights on a diesel during daylight. You will not see a red light on the rear of a diesel when it is pulling a train. So, for 1960s railways, no lights is more realistic than having lights unless you are modelling a night scene.

That's going to save my a lot of time and effort in fitting lights to my 1960's era Lima/Hornby Railroad diesel locos. I suppose it could apply to DMU's as well.

 

I think I remember from the distance past some sort of reflective mini 'jewels' that might give a better lit effect than paint?

[34theletterbetweenB&D]

I'm not a fan of DCC. I have a fair collection of DC locos from the last 3 decades, but I am about to buy new. It occurs to me that, while all new production is capable of running on DC, the circuitry may be optimised for DCC, and prolonged use on DC might not be ideal. Am I just a cynic, or is this an actual problem?

 It's a one-all draw in my opinion.

 

Hornby - unless they have recently altered the wiring paths of all their Sanda Kan period steam loco introductions - have a slew of mechanisms which are sub-optimal for DCC because the chassis block is part of the conduction path, and with flaky connections to boot. (DCC less tolerant than DC of brief track supply interuptions.)

 

Bachmann (after starting well with five pole motors when they kicked off the 'Blue Riband' introductions) now fit three pole motors on steam models. Good three pole motors, but not quite as smooth as the five pole motors used by Hornby, or from the various brands of motor available separately. (A good DCC decoder completely masks the motor performance difference, as will a BEMF equipped DC controller.)

 

The very cheap small capacitors used on steam mechanisms for suppression go 'phut' pretty much equally when running on DC or DCC in my experience. My opinion, after ten years regular operation about half the fitted suppression capacitors will have expired. While wholly agreeing with 'Bertiedog' that we should not be spraying random RF around, the problem  is not what it was. Between nickel silver rail replacing tin plated steel, better tyre materials and pick up technique, far smaller current draw motors, the spark generation at railhead and commutator is much reduced.

 

Combined with near universal adoption of digital transmission with its very powerful error correction, the nuisance interference of the past is non-existent. I recently watched the effect on terrestrial digital TV of a pair of low flying Chinook helicopters approaching the domestic aerial pretty much along the beam path from the transmitter. Just the occasional slight 'blocking' in the image until they had gone over. That would have been a wipe out on analogue broadcast.

[Pete the Elaner]

My exoerience is that chipped locos run slower and hotter than desirable. Replacing the manufacturers chip with a blanking plug immediately improves performance.

I was wondering why this difference of opinion exists between DC & DCC users.

 

DC users will be using 'DCC fitted' locos as an example. After all, they wouldn't buy a Lenz silver to chip a loco just to run it on DC. That would be a bit daft.

DCC fitted have cheap, old decoders which will have been bought in bulk. They are cheap because they do not work very well.

 

A DCC user on the other hand would be more choosy about which chips they use. They would run their loco on DC & find that it runs quite nicely. After all, they probably chose their chip because it gives good running.

[Crosland]

We had trouble with a brand new Bachmann B1 which upset a neighbours TV, 

 

Almost certainly down to poor aerial and/or wiring to their TV.

[Chris M]

I was wondering why this difference of opinion exists between DC & DCC users.

 

DC users will be using 'DCC fitted' locos as an example. After all, they wouldn't buy a Lenz silver to chip a loco just to run it on DC. That would be a bit daft.

DCC fitted have cheap, old decoders which will have been bought in bulk. They are cheap because they do not work very well.

 

A DCC user on the other hand would be more choosy about which chips they use. They would run their loco on DC & find that it runs quite nicely. After all, they probably chose their chip because it gives good running.

So there is little point in buying dcc fitted because the chips fitted don't work very well. I'm glad I'm sticking with dc.

[Pete the Elaner]

So there is little point in buying dcc fitted because the chips fitted don't work very well. I'm glad I'm sticking with dc.

For a factory fitted loco: yes, I agree. Some may be good, but you just don't know.

A S/H loco may be chipped with something good so I would not rush to strip it out.

 

If I had a choice of unfitted or fitted RTR for an extra £5, I would save the £5 & spend a further £19 on a Zimo M600, which I know will work.

[Suzie]

So there is little point in buying dcc fitted because the chips fitted don't work very well. I'm glad I'm sticking with dc.

 

Not always so. Some manufacturers at last have seen the light and are fitting Zimo decoders realising that the manufacturing cost of an excellent decoder is the same as a rubbish one.

[bike2steam]

It first started with 'DCC ready' locos, after finding a few that were poor runners, I ripped out the extra gubbins, and re-wired direct DC, and found it cured the problem. Since then , when the bargains have come up secondhand or new, I just re-wire all such locos, getting rid of all that extra wiring ( 'ready', and 'fitted') - now I have a pile of bits to get rid of from about 40 such locos that have been 'converted' over the last few decades. 

[Crosland]

It first started with 'DCC ready' locos, after finding a few that were poor runners, I ripped out the extra gubbins, and re-wired direct DC, and found it cured the problem. 

 

DCC ready simply means there is a socket and a blanking plug. Any active circuitry in such a loco works equally well on DC.

 

Messing about with the loco probably solved the real (unrelated to being DC ready) underlying problem.

[Revolution Mike]

It first started with 'DCC ready' locos, after finding a few that were poor runners, I ripped out the extra gubbins, and re-wired direct DC, and found it cured the problem.

 

So what part of the wiring did you remove that improved things? Or was the reality just that you fixed any issues with the existing wiring ie you may have improved the previous wiring (but that improvement would have improved DC and DCC.

 

I've not seen any wiring that "favours DCC" at the expense of DC, just the opposite in that frequently wiring gets dumbed down to suit DC users with a loss of functionality possible with DCC.

 

Cheers, Mike

[Pete the Elaner]

All the blanking plug does is take feed the track connections to motor & lights, so whipping the lot out & wiring the rest directly is the same as fitting the plug.