Bachmann J72 Decoder Install

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Hi Ed,

Commiserations. Just noticed looking at the pictures - where are the plastic spacers that go at the bottom (normally white)? If they are not there or worn or incorrectly inserted the frames can touch when torque is applied to the motor (and how do I know that one…? One ESU loksound decoder well and truly fried beyond redemption). The other 4 areas for shorts are the motor contacts, the brass worm/flywheel, the carrier gear axle (which should not be proud of the gear), and the nuts/bolts that hold the frames together. The first 3 are normally the result of issues with correct (or more correctly incorrect) frame spacing. If the plastic insulating sleeves for the nuts and bolts are perished or cracked (from repeated dismantling) then shorts are possible through the nuts and bolts when the frames are screwed together. The next time you dismantle the chassis it might be worthwhile using new plastic sleeves and spacers when reassembling. Plus some additional fiber insulating washers for good measure.

There is one other (remote) possibility for motor spiking, and that is related to the plastic half-axle centers. If they are cracked or split (and this is a common problem with Bachmann split frames) then there can be a momentary lock to the mechanism (accompanied by a click and jerk). Essentially a momentary stall. If they are split they will need replacing as they are almost impossible to repair. Needs a magnifying glass to check.

It's worthwhile drilling and tapping the frames from the top, rather than the sides, no risk of going too far and touching the other frame with the screw/bolt.

Lenz have a one year no questions asked replacement warranty that specifically  includes installation issues, I would try it, cut wires and all (cutting  the wires from the plug does not affect the functionality of a decoder, nor does hard wiring). Same goes  for Digitrax. For the cost of the postage……

Good luck with the next attempt. DCCing a split frame should be no more difficult than a regular cast frame with insulated wheels (apart from space issues, which means the big file). Try and get a female socket wired in (even as a temporary measure), then test with el cheapo decoder. I've seen all the problems mentioned above while converting a fair number of split chassis, and binned several along the way, especially the old Mainline/Kader models on which many of the Bachmann ones are based. Scorecard for the Bachmann GWR Manor: 4 attempts, 3 binned, 1 running. 


Nigel




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[user=1632]BCDR[/user] wrote:
Hi Ed,

Commiserations. Just noticed looking at the pictures - where are the plastic spacers that go at the bottom (normally white)? If they are not there or worn or incorrectly inserted the frames can touch when torque is applied to the motor (and how do I know that one…? One ESU loksound decoder well and truly fried beyond redemption). They're black, see picture below. The other 4 areas for shorts are the motor contacts, the brass worm/flywheel, the carrier gear axle (which should not be proud of the gear), and the nuts/bolts that hold the frames together. The first 3 are normally the result of issues with correct (or more correctly incorrect) frame spacing. If the plastic insulating sleeves for the nuts and bolts are perished or cracked (from repeated dismantling) then shorts are possible through the nuts and bolts when the frames are screwed together. The next time you dismantle the chassis it might be worthwhile using new plastic sleeves and spacers when reassembling. Plus some additional fiber insulating washers for good measure. Look fine. Loco has been little used and stored in a box most of it's life.

There is one other (remote) possibility for motor spiking, and that is related to the plastic half-axle centers. If they are cracked or split (and this is a common problem with Bachmann split frames) then there can be a momentary lock to the mechanism (accompanied by a click and jerk). Essentially a momentary stall. If they are split they will need replacing as they are almost impossible to repair. Needs a magnifying glass to check. Same comment as above.

It's worthwhile drilling and tapping the frames from the top, rather than the sides, no risk of going too far and touching the other frame with the screw/bolt. Could be the answer, see picture below.

Lenz have a one year no questions asked replacement warranty that specifically  includes installation issues, I would try it, cut wires and all (cutting  the wires from the plug does not affect the functionality of a decoder, nor does hard wiring). Same goes  for Digitrax. For the cost of the postage…… Have considered sending Hattons an email, they can only say 'go away', or words to that effect.

Good luck with the next attempt. DCCing a split frame should be no more difficult than a regular cast frame with insulated wheels (apart from space issues, which means the big file). Try and get a female socket wired in (even as a temporary measure), then test with el cheapo decoder. I've seen all the problems mentioned above while converting a fair number of split chassis, and binned several along the way, especially the old Mainline/Kader models on which many of the Bachmann ones are based. Scorecard for the Bachmann GWR Manor: 4 attempts, 3 binned, 1 running. 


Nigel




Could be that the screws I've put in the chassis/frame were just touching the edge of the motor housing at the back, and they're not now as I've added a few more slivers of insulation tape around the motor housing.



You may have 'hit the nail on the head' there Nigel :thumbs

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Ed,Nigel I have 2 mainline and 4 bachmann splits all running with hornby or gaugemaster decoders in only had one dud due to leaving the metal screws in the mainline motor, replaced with plastic ones now, so go for the cheapo`s they do the job,
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They were all reasonably cheap decoders  Owen.

The Lenz at £18 was the most expensive and it was the smallest one with the highest maximum current that would physically fit in the roof of the loco.

By choice I would have gone for a Digitrax DH126D which has a 2Amp max current rating, but it's just a bit bigger than the Lenz and wouldn't fit.

That's why one of the original ones I tried last year was the Digitrax DN136D which only has 1.5Amp peak current rating but is even smaller than the Lenz. Didn't cost me anything in the end, as I had it replaced under their 'no worries' warranty.

As it turns out, if Nigel is right and the screws I have used were touching the motor housing and causing a short, the smaller Digitrax would have been ok in the first place :thud

You live an learn, as they say :mutley


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You live an learn, as they say :mutley

this hobby is one big learning curve,Ithought my schooldays were over wrong!!!:thud
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Hi Ed and Owen,

Could be an "ah-ha" moment there. Bin there, dun that. Take the screw out and file the point down or use a brass washer on the outside. In which case you may need to file the top of the screw down a bit. Or invest in a mini drill and tap (Kadee do them for 2-56 bolts, and I think Eileen's has them for metric sizes) and go in from the top where there is plenty of metal (top of the boiler for example). Die cast metal (normally MAZAC or similar) drills like butter. If you are tempted you can solder the wires to the chassis but it requires zinc-rich solder and a special flux. Machine screws/bolts are much better.

I think you have to send the decoders directly to Digitrax or Lenz. Interesting to see what Hattons does. I'd definitely email them first.

1995 qualifies as an old model with the oil/grease incompatible/susceptible stub axle plastic. See below.

Mainline/Bachmann split chassis models are easy to convert to DCC with a 1 amp N-scale decoder, which has the advantage of a much smaller 6-pin plug, but if those plastic stub axles are gone (and it's a question of when not if) then it's game over. An easy check is to make sure the wheels do not rotate in the axle holder. They often run OK with one wheel/stub axle loose in on the carrier axle plastic, but when 2 wheels on the same axle go or one goes on the driving axle that's it as the quartering goes in interesting directions. An issue with the older Bachmann Manor model among others, and no spares available. Hence 3 in the bin (along with £170). Plus a couple of Mainline GWR Panniers and a Bachmann LMS 4-6-0. The wheel sets for the later models do not fit as they quietly changed the plastic and stub axle design a few years ago without bothering to publicize it. An NFFIP issue. If this was a car it would mean a recall.

Nigel


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I agree with you Nigel,drill &tap is way to go, I used the kadee tap for mine,as for the wheel sets,I got one from Bachmann u.k no problem,just make sure you give the model &number and state split axle(ok it was 2yrs ago)
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Well Chaps.

There's not enough space between the top of the chassis/frame and the body once fitted, for a screw head.

That's why the screw has to go in the side.

The answer is to drill another hole a bit to the rear so that the screw stays in a solid bit and doesn't protrude into the recess for the motor.

et voila



Few more bits of insulation tape, pinch a Digitrax DN136D from one of my Pugs that doesn't run too well, and………..

Avant d'accéder à YouTube

Robert is your father's brother !


Happy bunny :doublethumb



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well done that man,job jobbed at last and it runs well too
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Thanks Owen, just got to replace the missing handrail on one side and I've a nice little shunter.

I think if you and Nigel hadn't posted those last couple of ideas, it would have ended up back in the cupboard for at least another year, so many thanks to you both :thumbs


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I have one of those Ed - having bought it this century, it's a bit younger than yours but on reading this thread, I think mine can stay in the box.

Many congratulations on your tenacity and, more so, on your ultimate success - maybe in no half measures, thanks to Nigel's and Owen's suggestions.

I've all but given up on buying these "older" locos - cheap though they may seem, by the time you've expended all the blood, sweat, tears and toil converting them to DCC, the new version has lots of appeal - unless of course, you actually like doing this kind of thing…………:roll::roll:

I have a few DC locos that I'd always planned to chip but I'm rapidly changing my plans …………..;-)  I'll probably just offload them and start again with today's offerings.

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I very nearly put in on flea-bay after last years failed attempt Peter.

It's really only because I bought it around 20 years ago to run on my son's layout (which never really took off), the fact it's a very nice model and it runs so well, and that there isn't a DCC version at present, that made me have another go.

Know what you mean about the older models though. I'm not going to bother with the old Hornby Jinty I bought and re-wheeled, as I've since bought the Railroad version and although it isn't DCC ready, it was much easier to chip. It's also a much better offering than the older Tri-ang/Hornby model, even though it is just the Railroad version.




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Hi Ed,

Glad it's working - the obvious is often the last thing to investigate.

I'm with Petermac on putting decoders in old non-DCC models. Unless it's a model that is no longer made, DCC ready or equipped is the obvious choice. Less time and grief (and money). Unfortunately that' s a misnomer in many of the early DCC ready models that were wired in a hurry - they may have a plug but not enough room for a decoder and even less for a speaker*.

Nigel

*I can still hear Tony Wright muttering: "rip it out, rip it out" on investigating the innards a new DCC-ready locomotive. A perceptive comment.



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