Hornby A4

I really like my Hornby A4 but recently it became unusable, DCC constantly dropping out. It has loads of pickups, but a prod around
under the hood showed that there was no circuit between one side (the left?) and the chip. I dismantled it and found that the pickups on the loco transfer current to studs, with no solder or anything - the pickup strip is sandwiched against the stud by the underframe moulding. I soldered some thin wire on and ran it round and up to the chip, that has fixed the problem.
My word, though, this is a fiddly blighter. If it was in a Haynes manual it would have five spanners and a bloody microscope. I am staggered that I seem to have managed it without bending the connecting rods or breaking the underframe mouldings. I guess it's worth it if the running is restored to normal, this loco drive model is worlds apart from the tender drive A3.
Guy
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I have had the same problem with almost every model which uses this system. The idea of free pickups is sound but the locating method is a little random and the contact spigots through the chassis just a tad too short for comfort.
Regards
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On Fri, 2 Jan 2009 08:57:21 -0800 (PST), Sailor

A monster swearing session was required to get the bloody contacts in place and correctly located fore and aft. But it runs really sweetly, smooth, quiet and fast. So I now have five dependable models: the A4, N2, 8F (my favourite), Class 110 DMU (but I am considering fitting a Black Beetle because I hate traction tyres) and the Class 08 shunter, which has exceptional slow-running marred only by a tendency to stop on points (an artifact of DCC, as I can usually restart it). I wonder if a sprung chassis would help with that.
Enough to play trains, anyway.
Guy
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But did you need to get into the fun with the pickup? And what period are you modelling :-)
Cheers, Simon
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Nineteen mumble to nineteen harrumph.
Guy
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You seem to want to blame all your problems on DCC! First the WLAN, now poor running over points.
If a loco stops, it's due to poor pickup which is in turn due to the loco or poor track.
Sorry, but it's not a DCC "artifact" at all.
MBQ
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wrote:

Yep, sorry Guy but hes right.
Cheers, Simon
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It is certainly a "pick up " problem but not necessarily the actual pick-ups! Several of my "loco only pickup " chassis fitted on 6 coupled models will do this at slow speed and especially on courved points and those involved in banked trackwork! This is due to my use of insul frog type points where two wheels can encounter the insulators simultaneously and the third wheel is not in contact with the rail. This is a perfectly normal situation which is usually overcome by flange contact ( engineering fact = no surface in contact with another, no matter how flat, will be in contact in more than three places). The addition of tender pick ups and or bogie/pony truck fittings also ensures better performance but is by no means foolproof. Flywheel motors have the advantage and Hornby tyre fitted locos (and mainline) are the most susceptible.
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wrote:

Can also be overcome with a brief spurt of extra power as John pointed out a while back locos - esp shunters - werent treated delicately :-)
Cheers, Simon
Cheers, Simon
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<snip>

So it's problem a problem with how the track has been laid - either lay your track flat (relative to the loco, not base board or horizon) or use sprung chassis, it's not the electrons fault that they can't get to were they should be!...
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This is a perfectly normal situation which is usually overcome by flange contact ( engineering fact = no surface in contact with another, no matter how flat, will be in contact in more than three places).
Hmm. Not so, my boy. If you have sprung wheels on your loco all of them will be in contact with the rails. This is why P4 people (and even 00 people like me) habitually spring their locos. Also if you use low current basket wound motors (RG4s) you will find that the voltage drop at the rail/wheel interface is so low that you don't even have to clean your track. The 'toy train' manufacturers have ways to go to catch up on the technology now being used by finescale modellers. Hornby seem to have an inkling of the advantages of springing, as my new Black 5s have the rear set of drivers sprung.
Alistair Wright 5522 Models
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<snip>
Of course they don't need to be sprung, just 'flexible', hence why Mike Sharman came up with his "Flixichas" idea - now only falling out of favour due to the wish to model inside cylinders etc... Once the basic (Flaxichas) principles are grasped it's a simple and (almost) fool proof method of keeping all the wheels in contact with the track.
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On Sat, 3 Jan 2009 15:49:32 -0000, "Jerry"

Even double beam compensation provides sufficient flexibility for most of us. Our engines don't need to negotiate Mike Sharman's obstacle course.
Which was an amazing sight.
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Indeed, but it was just a demonstration to show the 'abuse' his system would put up with, of course one other advantage of his system was that it made all the wheel take a share of the total loco weight - thus problem wheel bases, such as 4-4-0, 0-4-2 and even 4-2-2 etc, would pull a respectable load without the need for extensive counter balancing or ballast-weights.
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Oddly enough Alistair I have no argument with springing - in theory! In practice I find that the effort required is not rewarded by the results. The "sprung" Hornby models have all given me trouble no matter which model large or small. They all develop rear axle oscillations. I have just spent weeks fitting a 7 pole motor to an old Hornby M7 and might as well have built a new one from scratch. I am a member of the S4 society and stay au fait which the art but reserve the right to choose. Basically rtr has advantages over the "Engineering" approach ( I am an Engineer) which more than compensate for rivet counting/precise colour schemes etc to those of us who want more than a Station ( or dept) with fiddle yards so beloved of the scale fraternity. My expertese goes into the control of my system as being a solo operator it does not suit me to have failures on the track -- I do not have sufficient eyes or (at my age) the patience to pick up the pieces after the crash.
Regards
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"Alistair Wright" wrote

sprung.
Have you ever seen one of the Hornby Black 5s which sits absolutely level? I haven't (they sit slightly high at the cab end) and I've looked at loads of them since their release. Springing is fine providing it is done properly, but locomotives which do not sit level are not acceptable to me.
John.
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I have seven Black fives on my layout (LMS Far North division - we only had Black 5s north of Perth). Five of them are Hornby (new type) and none of them are high at the cab end. If they were, the middle drivers would be lifted clear of the track which they manifestly are not. IF, and it's a big IF, you have one which is high and you think it is the spring, it is an easy matter to take a coil or two out of the spring or maybe even leave it off. I'm not needing to do this. I think this minor bit of springing, plus the tender pick up system now in vogue at Hornby (Bachmann may catch up - you never know) gives the best pick up I have ever seen on any RTR locos. I'm not really able to comment on the problems of 'unsul frogs' as my track is all handbuilt and has live crossings. I think insulated crossings are a nonsense and instantly mark a layout as a 'trainset'. I don't use DCC either as it wouldn't add anything to my operations so I can't comment on problems there caused by dodgy pick-up.
Alistair
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<snip> [ context left un-snipped intensionally ]

<snip>
I suspect John was talking about this from a traders point of view, he should not have to do anything to a new model...
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On Sat, 3 Jan 2009 02:48:52 -0800 (PST), " snipped-for-privacy@hotmail.com"

DC works just fine over the same point. If you get a spike or drop, the DCC decoder (cheap ones, anyway) drop out and have to be given another input.
OK, so it is not solely due to DCC, but DCC makes it worse. Or so my empirical tests would indicate, anyway.
Guy
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If you have spikes confucing the decoder then there's a serious electrical problem, maybe momentary shorts caused by poor decoder installation, or poor power distribution.
If the decoder in the loco sees a power or signal dropout then it's simply not picking up properly.
The decoder will "be given another input" as soon as the rail/wheels/ pickup give contact again. DCC commands are repeated constantly, even with no further input from the throttle.
MBQ
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