Bac Ivatt 4MT fixed, Bac Pannier issues, see last post

[Crumplezone]

Hello Gents,

I am wondering if you could shed some light on a issue I'm having with a Bachmann Ivatt 4MT.

I had a Hornby decoder in it and it worked fine for abit but I had to do some bodywork and unfortunately due to the fiddly shape and decoder area for the Ivatts wires came off it and the decoder was busted. My issue is that I moved another decoder over into the Ivatt 4MT after doing some weathering to the locomotive, when popped down on the track and running at I believe 2 clicks in on the speed which has it moving at a slow running speed the loco was basically running then jerking into a higher speed then becoming jerky to slow speed then spurting off again every 3-4inches.

Now I thought are the wheels and track dirty? So I track rubbered the rails and cleaned up the wheels on the area where the copper pickups drag on, abit of black dirt came up but then it was clean after about 10mins of cleaning.

Next check I took the decoder out leaving the chassis off and put the blanking plug back in and ran it on DC, perfectly fine at one click on the controller, moved along at a nice slow pace with no jerkiness.

So I took the decoder and put it in my Bachmann 9F which I hadn't chip fitted yet, 9F is just fine, runs smooth and quiet and has zero issues so it doesn't seem to be decoder or the Ivatt 4MT. The Ivatt 4MT does have one yellow capacitor sitting on the decoder socket but I'd not had issues previously with the Hornby chip. Unfortunately I'm not sure what model/number the decoder was that I moved into the 9F as it was pre-installed into a secondhand loco previously, it looks like a Hornby one, but quite frankly it also looks like a Bachmann one, its a blue circuit board.

It was always more jerky when moving forward under DCC control while using the above decoder mentioned, but on DC its fine in both directions, so I'm somewhat stumped on what the issue could be.

So before I take it to my local model shop to have the dcc bloke have a look at the loco, does anyone possibly have a clue as to what might be causing it? I don't think its the motor or gears either as there is no grinding sound or juddering under DC which would point towards a tooth on a gear being broken.

 

[smokebox]

You say "Now I thought are the wheels and track dirty? So I track rubbered the rails and cleaned up the wheels on the area where the copper pickups drag on, abit of black dirt came up but then it was clean after about 10mins of cleaning."

 

Have you also cleaned the wheel treads?

[RFS]

Is the decoder now a Bachmann one? In which case you need to set the Back EMF CVs thus - http://www.Bachmann.co.uk/pdfs/decoder_settings.pdf

[Crumplezone]

Yes I forgot to include about the fact the wheels were also checked, they a bright silver colour so I don't think they could get any cleaner.

Its possible the back EMF could be having issues, though I would have to try with a new Bachmann decoder as the decoder is now in the 9F and runs smooth even on slow speed so I'm inclined to keep it in that one to not cause anymore issues. Main issue is I don't really know what that decoder is and I don't have the equipment which reads the decoder to find its brand.

I'll drop back in here once I've obtained a new decoder for the loco and see if its the same issue still pop up.

I had very minor jerkiness with my 8750 pannier tank and that has a 36-553 decoder fitted, looking at the chart provided in the pdf the closest equivilent loco would be 56xx so I may try those values to see if that smooths it out, but if anyone has back EMF values for it I would appreciate them being posted.

 

[RFS]

To find out the brand and version of a decoder you just need to put the loco on the programming track and read back the values of CV 8 (manufacturer id) and CV 7 (version id).  Bachmann decoders should have a value of 151 in CV 8.

[smokebox]

What controller do you have?

[Crumplezone]

Hornby elite at the moment Smokebox, I know not the most powerful or best equipment but I've had it a few years and its updated to latest firmware nore do I have 200 odd quid laying about to get a new system so stuck with it for the time being.

The decoder which I moved over to the 9F which was having issues with the ivatt has 151 in cv 8 so we can assume its a Bachmann and cv 7 is value 88.

Edit: I feel like a right numpty, taking into account the back EMF values for the ivatt 4 which is supposed to be according to the chart 12 and 63, reading the values on cv 54 and 55 show 32 and 24. I am assuming that these quite sigificant swings in values are what is causing the Ivatt to jerk about. I will have to refit the decoder back in the Ivatt to check but it possible looks to be that issue.

[34theletterbetweenB&D]

Bach's 36-553 decoder has a BEMF set up optimised for larger motors with significant drive line inertia. It goes straight into their diesels and works beautifully thanks to fat motors with flywheels. It is also decent on factory settings with the 9F, which has a flywheel. You have to be prepared to nudge about the suggested values in CV's 54 and 55 to find the 'sweetest spot' to run small motors. But honestly I wouldn't bother.

 

Do yourself a favour and try a Lenz Standard. There isn't a Bachmann small OO motor I have found yet that doesn't immediately respond sweetly to this decoder, with no fiddling around required.

[Crumplezone]

I'm happy to report that the issue with the Ivatt 4s jerking about was in fact the back EMF values being set to the values for a bigger motor, adjusting them to the chart which was provided earlier did indeed make the Ivatt 4 run smoothly again.

The decoder which I accidentally broke was probably already setup by the gentlemen who had fitted the loco for me which I had done because of the extremely fiddling backmann 4MT chassis for decoder fitting. The decoder which I had moved across I had pulled out of a Q1 which had run smoothly but I suspect the back EMF values had been refined for the Q1, it was a tempory job but I hadn't really thought it would have much issue with the Ivatt to I ran it recently after weathering.

So there you have it, if your loco runs jerky while under DCC but smooth on DC, check BEMF values and don't assume the values are already suitable for your loco.

I will look into a lenz standard for the ivatt as I've put the decoder back into the 9F since it was running great in that which as mentioned is due to the fat motor and flywheel setup.

Thanks gents, numpties like me need that extra bit a help at times

[Crumplezone]

Hey gents,

solved the issue with the Ivatt but the pannier is being problematic at the moment. The issue I'm having is at slow running speed which on the Hornby elite is one "pie piece" before you get the solid black block pie piece icon, is that the pannier keeps stalling over pointwork. They are peco set track points, have had Hornby dcc clips popped on and removed and I've had a Bachmann Jinty, 56xx, 9F, and standard 4 2-6-0 run over them just fine.

However the pannier when its passing between middle drive wheel and back drive wheel will stall and stop on the points near the transition from the triangle plastic bit to the point directional hands. Pressing down on the pannier will make it move again and a nudge will to, but at the smallest increase in speed on the controller it just keeps cutting out, above the first little notch and into 2nd and 3rd black speed indicator pie pieces it'll run just fine over the points, no stalling or anything, just  on slow speed it judders and stalls. It also only seem to happen in reverse, not forward.

I've cleaned the wheels, cleaned the area where the copper pick ups sit on and didn't really see any issue. I lowered the back EMF values to account for the smaller motor, still same result. I also removed the decoder and tried to run it on DC, it did stall a few times but was more stable. I've also removed all 3 yellow capacitors to eliminate issue with signal to decoder.

I tried adding some 1p coins into the cab encase it was related to weight so more weight would be on the back driver which seems to be where its stalling on, but no real joy in stopping the stall on the pointwork.

All my other locos don't have a issue on super slow speed, just this pannier so I don't think its down to equipment or track and the points are brand new today and I ensured to check for tarnishing and track rubbered them, but as mentioned the other locos are ok over the pointwork.

So my question is, any ideas on what could be causing this problem with the pannier? Its fine above the super slow speeds and runs along without a care, so I don't think its a faulty loco and there is no grind, clicking or wierd look to the gears, I checked this on without the chassis on.

I guess it could be the rear wheel pickups, but I'm not sure how I would go about checking or fixing this.

Thanks in advance.



 

[Combe Martin]

The Pannier's wheels may be tilting away from the pickups when they go over a piece of 'un-level' track like plastic point frogs.  I had this problem with a Bachmann Jinty (but not a Pannier).  Turn the Pannier upside down and try tilting each wheel set in turn in both directions so that the axle/wheels are not level, and see if one of the wheels comes away from it's pickup.  If it does you will have to bend the pickup 'out' a bit.  This might mean you have to remove the keeper plate to get at the pickups.      

[Crosland]

As well as checking the loco wheels/pickups, place a straight edge at right angles across the points and move it back and forth to check if the rails and frog are truly level.

 

Andrew

[Crumplezone]

Thank you both of you. I have checked the level of the pointwork and it does seem to be flat, I ran piece of 2mm solid card back and forth and there was no catching or bump to it, spirit level also shows its flat both on the turnout arm and the entire straight length and other tracks are not pushing the pointwork up and making it hover off the wood.

If I'm understanding the previous comment, each wheel should still have its  copper pickups sat on the wheels inner side even with the left to right "give" you get in the wheelset? The backwheel has one of the gears attached and doesn't have as much left to right motion as the front and middle drive wheels from what I could tell after posting. I took the keeper plate off  lastnight and removed the wheels and had a look at the copper strip with the arms for the pickups, front and middle were noticable more bent away from body while back was less bent outward.

I had assumed they were less bent outward due to the back wheel having less left to right motion but I did note some wheels when pushed left to right were not touching on there copper pickups.

So I just need to bend them out maybe a few mm's more and ensure they always are in touch with the wheels without them fouling anything?

Sorry if this seems very "basic" or simple information, I've not really needed to do any of this in the past or present as most locos have been just happy to run without issue.

[Combe Martin]

Yes, you need to make sure all the pickup strips are always in contact with the wheel backs.  As you say, when the wheel set is moved left to right, but also when the axle is tilted which is what can happen to the trailing one when the loco runs over the point frog, in this case when the leading axle wheel drops into the 'hole' in the crossing V. 

[Crumplezone]

I pulled the pannier apart on the wheel area and moved the copper arms so they rest on the wheel inner rims on each wheel when the wheels are pushed to their max left to right motion and I can see they are all connecting just fine after abit of adjustment. Still however the pannier seems to be at times stop dead or doesn't get over the pointwork on the first "pie piece" speed indicator on the Hornby elite. I've basically got the dial turned enough up on the first slot enough that one more minor turn will give you the second indicator and speed the train up to I would think around 6-9mph scale speed.

I do think its working better now, but it just doesn't seem to be happy with the slow speed on first indicator, while a Jinty and 56xx will just plow over the pointwork or straights just fine. The track is clean, the wheels are practically silver they even got a shine to them so I don't think its dirt interference and the copper arms still look copper colour and not tarnished or blackened.

I'm not sure what else to try with it as the pannier, I don't think its a motor issue otherwise it wouldn't run smoothly in the next speed slot and I'd expect jerking about all over, the decoder works fine and I adjusted the back EMF to the values my Jinty has and smoothed it out abit with +1/-1 adjustment. Just the odd not starting or general stall.

It happens almost regularly while in reverse but forward it is just fine to. It could be the red and black white from the copper strip to the decoder socket, but I'm not really qualified to say it is as looking at it looks fine to me.

I haven't changed any of the voltage cvs or speed cvs for low mid and high point they should be decoder default, would any of these be the culprit before taking the loco to the shop to have the dcc gent look at it?

Its important I can get this loco running on the slower speed as my layout is going to be a branchline terminus with goods sidings and 2 road engine shed, so the next speeds steps are alittle to fast for what its going to be doing.

[deadlyduck]

Hi,i would check out the DCC Concepts Zen ZN8D decoder,its smaller than the 8 pin plug it replaces.It also comes with 2 wires attached to the decoder which you can attach the small stay alive unit that comes with them.this will give you a few seconds if the electric power is intermitant.Ive bought 11 so far,they are fitted to Bachmann/Hornby steam locos they are all working well

David

[Crumplezone]

Thanks for everyone's input so far, I'm opting to return the pannier tank and now a complete defunct Jinty which was purchased only a few weeks after the pannier from the same shop. The Jinty was making a grinding sound in reverse then has tripped my Hornby' elites short circuit protected to reveal a burning silcon smell and a buggered decoder all in one go. Much to my annoyance also the decoder in the Jinty wasn't in a jacket so burnt fingers while removing it via wiring from the chassis to ensure the Jinty still worked correctly, Jinty still works but I'm not going to risk anything else with swapping another decoder in from another loco and just return both it and the pannier.

I kinda expected them to work like my other 3 locomotives, one which is a sound fitted 56XX, the 56XX has zero issue over any of the track and I think if there is a issue with track or controller/signal sending then it would be the first to show the issues before any of the non-sound fitted ones, but it doesn't so I assume its to do with the locos instead.

Its abit of a shame, but I suppose we have to deal with these issues of potential faulty locos from factory, especially when Bachmann outsources production to china and then brings them here to the UK.

Once again, thank you all for your advice and help, its been much appreciated and has helped with bringing me up to speed on things and I'm happy to say I've tried everything to ensure they work correctly.