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Heljan 89121 Turntable 180 degree turn fault


Pete22
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Hi, can anyone please assist ?

My Heljan turntable 89121 slightly overshoots by about 1 to 1.5mm when using the 180 degree turn function (pressing Go To twice).

The TT works well and always goes accurately to each programmed track. This 1 to 1.5mm overshoot is enough to derail the bogey on my Hornby Britannia. 

I came across an old post that included this same problem, member Free At Last mentioned it in http://www.rmweb.co.uk/community/index.php?/topic/54336-Heljan-uk-89111-turntable/page-2

.

I have deleted, calibrated and re-programmed several times, but can't seem to cure this issue, so any advice would be most welcome .

Here are some photos showing the issue :-

post-17993-0-05057000-1527120031.jpg

post-17993-0-16357600-1527120095.jpg

post-17993-0-43181500-1527120130.jpg

 

Many thanks,

Peter...

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As you may have noticed I gave up on my post as others were thinking it was a programming error.

The bridge/rail alignment on mine is not 100% true. Why it was only on mine I don't know as no others reported this problem.

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Hi, Thanks.

I really don't think it has anything to do with my programming regarding track stops.

Either the bridge is slightly bent (I don't think so), or the 180 deg (steps ?) function is wrong ! i.e. it is adding another 1 or 2 steps thus making it overshoot consistently by about 1 to 1.5mm. In my photo 2 above, after the bridge travelled to track position 3 , then performing a 180 deg turn, you can see that it has overshot the exit rails at 3.

 

I am using my TT being powered from my DCC rails (wired as per the instructions), but only use the Heljan control unit to operate the TT, not via DCC programming.

 

N.B. Have you contacted the importers (Howes Models I think ) ?

Or- have you tried contacting Heljan in Denmark ?

 

It would be useful if any other owns of this TT could post a couple of photos like mine above, just to show that an accurate 180 deg turn is possible.

 

Cheers,

Peter.

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Have you tried marking the bridge rail positions on either side of the pit then trying a 180° turn to see if both sides re-align or just one like mine?

I don't think anyone came back with the same problem which makes me wonder why mine is like it is. There doesn't appear to be any damage to the model.

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Peter,

 

I have had this turntable for five years and never experienced the problem your photos show.  Has the problem always been there or has it developed over time?  When you press Go twice, does the bridge continue to turn in the same direction or reverse its direction?  Before I had the Heljan, I had the Hornby turntable and gave up on it because it never aligned properly if the direction of rotation was changed, but I have not had the problem with the Heljan one.  I don't see how the problem can arise from your programming, since the 180 degree turn is preset.  I think it woould be well worth contacting Hejan in Denmark about it - I created a problem with mine when something was dropped onto the bridge and they were most helpful.  I used email to contact them and eventually sent the whole thing to them for testing (not easy after it was fully installed).  I had to pay for the repair - it was my fault after all - but it has worked well ever since.  Their website shows the following link Heljan@Heljan.dk

 

Good luck!  The current performance is clearly unsatisfactory.

 

Harold.

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Hi HLT, - I think it travels in the same direction when it does the 181 degree turn ....

This fault has been there since I bought it, but although I noticed it I did not pursue it at the time, nor did I realise how badly it affects using the TT, I have been devoted to building scenery etc since I installed it very carefully. I finally started to place my locos on the layout for the first time the other night & tried revolving my Brit 4-6-2, that's when it derailed - so I investigated further.

 

Hi Free At Last, - I think your fault is exactly the same as mine, yes you could try to move the rails, but I recon the fault is in the firmware (or the step counter) which is causing it to overshot by a step, thus equating about 1.5mm. Or I suppose it could be a slightly off centre pivot point in the turntable well........but more likely to be firmware / step counter ?

 

Thanks,

Peter...

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If both the entry and exit track align one way and then only one aligns after a 180° turn it is a physical error not electronic. No programming/firmware  can correct that.

 

Pete22, I note from your picture that you don't have a through track on your turntable installation. Have you tried marking one out and then rotating the bridge 180° to see if one or both sides re-align?

 

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does it happen when ever you do a 180?

 

so, if you created a new "index" position, say 12oclock and 6oclock ( if you catch my drift ) does it still mis align?

 

how does this turntable work? motor / stepper motor / controller / indexer ?

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Peter,

 

I think it worth doing what Pete suggests - ie " Have you tried marking one out and then rotating the bridge 180° to see if one or both sides re-align?"  At least you will have an indication then as to whether it is a software or hardware problem.  Also, as you have other rays from the TT, does the mis-alignment happen at each of them (as ianjeffrey asked)?  For example, having set the exits so that alignment is correct for the cabin end of the bridge, if you do a 180 at each of them, does the fault recurr? 

 

I had a close look at mine this afternoon while doing a 180 using the Heljan controller rather than my NCE powercab.  As you suggested, it turns clockwise with each press of the Go button.  There is a small difference in alignment but I have never had a derailment as a result.  Like yours, the alignment is correct at the cab end but after a 180, the bridge stops about 0.5mm short of the correct position.  I don't have "a straight ahead" exit at that spot so didn't check the other end - but I do have one in another position so will check tomorrow.

 

Looking at your photos, in the first one, the rail on the left of the picture appears to be already slightly out of position, and on the second photo, the discrepancy seems greater on the same side - but of course, it is the other rail.    If the problem is only at ray 3, you could bend the left approach rail slightly left  (pictures 1 & 2).  If you don't want to refer the problem to Heljan, is there any mileage in bending the errant ends of the rails to make then align?!!  A bit drastic and needs careful thought that it wouldn't cause problems in other positions - might be easier than moving the whole of each rail.

 

Just had another thought - if you were to reprogram the exit so that the alignment at the cab end was correct for the left rail in the top picture (or even a tiny bit short) then after a 180, the alignment in the second picture would be closer - possible sufficient not to cause a derailment.

 

I hope some of this is helpful.

 

Harold.

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Hi all,


So much good advice ! many thanks..


 


I have worked on my layout again tonight and :-


Checked that the rails in the bridge are straight using a steel rule as a straight edge, they are straight using the rule.


Added some code 83 rails at the opposite side to the entry track (track 3).


Reset - calibrated - programmed track 3 - calibrated - programmed track 4 - calibrated.


The photos below show that the bridge cabin end turns 180deg to accurately line up with the new rails that I added opposite entry track 3, BUT the non cabin end does not line up correctly with the entry track !


I also post photos showing what happens with track 4...


I am loosing my mind trying to figure this out, and can't decide if the fault is firmware allowing overshoot, or if the bridge is skewed slightly in the well ??


 


Track 3 re-programmed:


post-17993-0-55898900-1527291048.jpg


 


Rails added opposite entry track 3:


post-17993-0-10649600-1527291156.jpg


 


Cabin moves correctly to new rails opposite entry track 3.


post-17993-0-52298200-1527291209.jpg


 


Non cabin end now does not align with entry track 3


post-17993-0-55222500-1527291288.jpg


 


Track 4


post-17993-0-29142800-1527291321.jpg


 


Track 4 after 180 deg turn


post-17993-0-07464600-1527291399.jpg


Edited by Pete22
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Have you tried reversing the table in the well to see if the misalignment gets reversed too?  Always supposing it will go in either way.

 

IIRC from last time I had anything to do with one of these, it is possible to remove/replace the bridge unit without needing to reprogram.

 

That should help identify whether the fault is in the hardware or the software.

 

John

Edited by Dunsignalling
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Pete22, on 26 May 2018 - 00:21, said:Pete22, on 26 May 2018 - 00:21, said:

Hi all,

So much good advice ! many thanks..

 

I have worked on my layout again tonight and :-

Checked that the rails in the bridge are straight using a steel rule as a straight edge, they are straight using the rule.

Added some code 83 rails at the opposite side to the entry track (track 3).

Reset - calibrated - programmed track 3 - calibrated - programmed track 4 - calibrated.

The photos below show that the bridge cabin end turns 180deg to accurately line up with the new rails that I added opposite entry track 3, BUT the non cabin end does not line up correctly with the entry track !

I also post photos showing what happens with track 4...

I am loosing my mind trying to figure this out, and can't decide if the fault is firmware allowing overshoot, or if the bridge is skewed slightly in the well ??

Thank you for doing this, this is the problem I have always had with mine. I think it is a fault in manufacture, either the deck rails have not been laid accurately or the deck centre bearing is off centre.

I have never understood why others have never reported having the same fault, perhaps they have never noticed due to not having a through track or not all models are affected 

Edited by Free At Last
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Hi Dunsignalling.

 

If I remove & reverse the bridge, I can place it anywhere within the arc, so yes I could make it line up ( probably depends also on where the little drive cogs are aligned to the cogs in the well), but i'm not sure this would prove anything........

 

Hi all, - If there was a way to calibrate the position after performing a 180 deg turn, that would solve the problem !

Does anyone know what the position number is for where the cabin aligns to after a 180 deg turn ?

I deliberately didn't place a track exit directly opposite the entry track 3........I think I read this somewhere, but now I cant find this in the instructions.

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Gentlemen,

 

I too have been playing with my turntable - and I must confess that I do have a misalignment problem with a 180 - not noticed it before as the TT is on a lower level so not readily visible from above.  Clearly it has not caused a problem as I have been using it regularly for five years.  However, those looking for the cause might try this: When my TT misaligned by 0.5mm or so, I discovered that, if I pushed sideways against the deck at the offending end, the whole bridge lifted slightly at that side - ie in its natural position, it was slightly tilted.  When pushed as described, the track aligned.  Thus, in my case, it appears to be a phyisical problem of the socket in which the pivot of the bridge sits, being slightly oval - at least that is what I think.  I must say, that the misalignment is not the same with each ray - and the closer the alignment after a 180, the less sideway rock there is with the deck.

 

I tried a work-around.  In Peter's problem with ray 3, if the bridge position is programmed to be (say) 0.5mm short of where it should be at the cab end then, after a 180 there will be 0.5mm less of a misalignment with the other end - possible sufficient to prevent a derailment.  It is not a perfect remedy but may be the "least worst" solution.

 

Interestingly, although the bridge normally turned clockwise when asked to do a 180, it did occasionall turn anti-clockwise - didn't affect the outcome.  All testing was done with the Heljan controller not my NCE stuff.

 

I said previously that I do have two rays opposit one another - rays 5 & 9.  Until today I have not programmed ray 9 but used ray 5 when wanting to access the other end.  Today though I have programmed ray 9 (which is only a mis-alignment amount away from the opposit end of 5) and it works.  Regarding the number of the ray at 180 from a programmed ray, I suspect there isn't one.  The Heljan instructions say that rays 1 & 2 are the opposite ends of the calibration point (which is why we have to start at 3.  If I am correct (and my experience with my rays 5 & 9 today suggest I am) there would appear to be no reason why the non-cab end of ray 3 can't be 4.  Thus each cab end would be an odd number and the others even.

 

Harold.

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Hi HLT,

If I understand your point correctly, I could try to program another track exit directly at the opposite side ........for example, keep main entry track 3 but create a new exit track number directly opposite 3 and call it 4 ?.....thus instead of doing a 180deg turn by pressing go-to twice, I would just select the new exit track number.

Good thinking !.......this may work :)

 

I will try this soon when I next get to my layout and will let you know how I get on..

 

Peter...

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Peter,

 

Yes, that is what I was suggesting.  During my playing, I wondered what would happen if i inseerted a ray number between two existing ones - or even if it would let me do it.  It worked perfectly - I put my new ray between 4 & 5, numbered it 5 and all subsequent rays numbers increased by one.  I thought I might have to reprogram them all.

 

Hope it gives you a good result.

 

Harold.

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Hi Harold, et all. 

 

It Works !..

I have now successfully programmed new/additional exit tracks opposite each of my existing tracks. These imaginary tracks allow an accurate 180deg turn by just selecting the new track numbers.

I guess I have just been unlucky and my TT has an unusual inherent slight geometrical fault which prevents the inbuilt 180 deg turn feature from working accurately, this is a shame as in all other regards the turntable is an excellent & reliable model. I may contact Heljan about this, just to hear what they have to say !.

 

Many thanks to all above, your thoughts and advice have been most helpful.

 

Regards,

Peter.

Edited by Pete22
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Late to the party I admit but my suggestions would have been...

1. The bridge track and stub track gauges appear to be out, one looks wider than tother.

2. Would it have been possible to rearrange the TT mechanism cogs to present unworn teeth at the critical arc points.

Rob

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Hi - Again,

One last question, has anyone tried lubricating the TT motor / gears yet ?.....I would like to do this, and was going to use "Electrolube " loco oil for the spindles , and Vaseline for greasing the gear cogs , would this be ok ??

 

Hi Rob,

Yes I think the track must be slightly out of trim, but as I seem to have a usable solution now, I am not keen to send it back to Heljan ( but let's see what they say)..

The TT cogs should be unworn as the TT has hardly been used.

 

Thanks once again..

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Peter,

 

I think electrolube would be the wrong thing to use, as its purpose is to aid electrical conductivity - surely not what you want on the spindles.  I did take the cover off my motor with the intent of lubricating but it didn't seem to need it.  More important is to keep all mechanisms clean - particularly the cogs that run round the well and the rack they run on.  Not sure about Vaseline - you must  only use lubricants that are safe for plastics.  Can't remember the name of the oil I use but it came with the correct spec - I can look it out tomorrow.  I haven't used any grease on my models.

 

Harold.

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Hi Peter,

 

The oil I use is Woodland Scenics Hob-E-Lube.  It is in a tube with "an extension tip" and has lasted me the best part of 10 years.  If you Google Hob-E-Lube you will find that it is a range of oils and gresaes that are warranted safe for use with model plastics and paints.

 

Hope this helps.

Harold.

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Hi Harold,

My TT could sound quite rough sometimes, that's why I wanted to check it's lubrication internally. I have now applied silicone grease to the plastic cogs & brass worms, so plenty of lubrication taking place now. I only used the oil to lightly lubricate the motor spindles & the cog spindles at each end of the bridge. 

I think the way the cog spindles sit into their seats inside the motor housing is very basic and so I was getting some chatter sometimes when in use. Also the plastic cogs only just connect with the brass worms, so lots of play exists.

The grease has in effect taken up some excess play, so there is now less movement and noticeably quieter running. I will inspect it again in a few months just to check all is well inside. Silicone grease is fairly inert, so (as I read) it should be ok with plastics.  I guess the cogs are probably made of nylon for durability.

 

Just back in from the layout tonight and I have programmed in all the exit tracks, each with 2 programmed numbers (normal & 180 deg turn), the TT now operates very well indeed, and I am pleased !

 

Thanks again for your help ...

Peter.

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