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Offline applor  
#1 Posted : 17 April 2018 01:55:15(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,652
Location: Brisbane, Queensland
Hi gents,

I was making far too much constructive progress on my layout so Mr Murphy decided to visit and have me waste time fixing another issue.

This time it was my new 7286 turntable. I have been working on it lately and happened to notice that the track height between the bridge and spokes were of an unacceptable height difference.

IMG_1425.JPG

At first I thought perhaps something I had done may have caused it, such as the turntable not being flat (not that I could see how that could cause this issue) or similar.
I ended up removing the turntable completely and setting it down and testing with individual spoke tracks.
The height problem was still there and I was somewhat relieved that the problem was still there with other factors removed.

Given the bridge sits on wheels and its height is fixed for the turntable circumference, it was clearly a case of the spoke track sitting too high.
Here we can see however that the spoke track is fully inserted and sitting as flush as it can.

IMG_1426.JPG

Looking at the underside, the solution is clear - I must remove some of the plastic so that the spoke track sits lower.
Why has this happened? I am not sure. A couple of my other spoke tracks appear to sit at the right height. I can only assume a manufacturing issue.

IMG_1427.JPG

After having removed the excess plastic from the underside, the spoke track now sits at an even level.
I was not particularly precise with removing the plastic (I used a dremel with disc) however taking off too much is not a problem as you can sit them at the height you need and they will stay there because there is a lot of friction with the adjacent pieces and the socket itself.

IMG_1428.JPG

I must not be the only person with this issue?

I do believe I have seen other photos where the track height is not level, though given the transit speed is slow I think most people accept the small bump as the locomotive travels between the spur from the bridge.
Those who may have this problem can now see the cause and how it can be corrected.

Edited by user 20 April 2018 04:18:36(UTC)  | Reason: Not specified

modelling era IIIa (1951-1955) Germany
thanks 4 users liked this useful post by applor
Offline mvd71  
#2 Posted : 17 April 2018 09:08:47(UTC)
mvd71

New Zealand   
Joined: 09/08/2008(UTC)
Posts: 1,702
Location: Auckland,
Hi Eric,

You are not the only one with the problem, you just have an eye for detail and a desire to get things right.

When I get time to get back to build train layouts my turntable will need the same treatment

Cheers....

Mike
Offline JohnjeanB  
#3 Posted : 17 April 2018 12:51:35(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,078
Location: Paris, France
Hi Eric,

No you are not the only one. One issue with the Fleischmann/ Märklin turntable is the problem you describe and another is a spoke track difficult to insert all the way into its place (especially when you cannot remove the entire TT and its track). I had to create a little tool - with strong steel wire- to support the bottom of the TT while pushing down on spoke rails to avoid breaking the TT. I had also to file a little some of mine to avoid using excessive force during insertion.

It is much better to solve all these issues before all scenery / landscape is finished.
We all love attention to detail and I must go back on my turntable because one of the spoke rail seats to high just like you.
Bon courage

Jean
Offline applor  
#4 Posted : 18 April 2018 00:59:35(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,652
Location: Brisbane, Queensland
Thanks for the replies gents.

I decided last night it was about time I actually test my turntable with a controller.

I figured it best to start with the included analogue controller. It rotates left and right fine, however to my dismay it does not stop at 7.5d intervals when that mode is selected!

Yet another issue to fixCursing
modelling era IIIa (1951-1955) Germany
Offline PJMärklin  
#5 Posted : 18 April 2018 14:03:38(UTC)
PJMärklin

Australia   
Joined: 04/12/2013(UTC)
Posts: 2,204
Location: Hobart, Australia
Originally Posted by: applor Go to Quoted Post
...I have been working on it lately and happened to notice that the track height between the bridge and spokes were of an unacceptable height difference. I must not be the only person with this issue?...



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Offline JohnjeanB  
#6 Posted : 18 April 2018 16:05:49(UTC)
JohnjeanB

France   
Joined: 04/02/2011(UTC)
Posts: 3,078
Location: Paris, France
Originally Posted by: applor Go to Quoted Post
Thanks for the replies gents.

I decided last night it was about time I actually test my turntable with a controller.

I figured it best to start with the included analogue controller. It rotates left and right fine, however to my dismay it does not stop at 7.5d intervals when that mode is selected!

Yet another issue to fixCursing


Hi applor

If you use an unmodified 7286, then I think the turntable will stop at the next "full spoke track". There is a latch under the bridge that will cut off the motor when engaged in a "full spoke track" and maybe also an "opposite spoke track" (I am not sure about this last one). A solenoid disengages the latch and starts the motor for another "trip".
This may be the reason why you can't stop at 7.5°. My TT is controlled by a DigitalBahn DSD 2010 which is not using the latch but an optical sensor and 2 processors (one on the bridge and one master board).

Cheers

Jean
Offline applor  
#7 Posted : 18 April 2018 23:47:16(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,652
Location: Brisbane, Queensland
Originally Posted by: JohnjeanB Go to Quoted Post

Hi applor

If you use an unmodified 7286, then I think the turntable will stop at the next "full spoke track". There is a latch under the bridge that will cut off the motor when engaged in a "full spoke track" and maybe also an "opposite spoke track" (I am not sure about this last one). A solenoid disengages the latch and starts the motor for another "trip".
This may be the reason why you can't stop at 7.5°. My TT is controlled by a DigitalBahn DSD 2010 which is not using the latch but an optical sensor and 2 processors (one on the bridge and one master board).

Cheers

Jean


Yes it is still unmodified (I have a LDT decoder not yet connected) and so the latch is not cutting off the motor. I need to pull it apart today and try and determine why.

PJ - I see your second picture has quite a difference in rail height like mine did, though the other 2 appear OK.
modelling era IIIa (1951-1955) Germany
Offline applor  
#8 Posted : 19 April 2018 09:12:41(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,652
Location: Brisbane, Queensland
Hi guys,

Perhaps I could get some assistance on how the analogue controller is meant to work.

The left side selector has 3 positions - up (continuous) middle (off?) and down (one segment only) and then you have the right side direction knob.

At the moment it doesn't matter what the left selector is set to, as soon as I tun the right knob in a direction, the turntable moves and only stops when I re-centre the knob.

Are you meant to choose your movement option on the left selector and then turn the knob and re-centre when approaching the right spoke?

Or are you meant to leave the right knob in the turn direction and then move the left selector to either the up or down position and the turntable should not move when that selector is in the middle position?
modelling era IIIa (1951-1955) Germany
Offline applor  
#9 Posted : 20 April 2018 04:25:04(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,652
Location: Brisbane, Queensland
I pulled apart the motor unit and took a look and I have identified the problem.
Again it seems there is a manufacturing issue.

The problem is that the momentary contact from the coil was permanently energized. This is because the metal tab construction has a thin tolerance and appears to have been insufficiently aligned.
A picture tells a thousand words though, so here is what my unit looked like before work began with the momentary coil contact circled.

As you can see they are making contact which should only happen when the slider bar is not locked into the gear socket.
On my unit even when the slide bar was locked into the gear socket the contact was still touching its mate.

IMG_1434.JPG

I then removed the motor and identified the cause. Here you can see that contact is a metal strip to the opposite side and is quite flimsy metal with a lot of room for error.

IMG_1435.JPG

I then carefully adjusted the metal strip so that the contact tab did not touch its mate when in the locked position and would make contact when the slide bar was engaged back.

IMG_1436.JPG

That should be the problem fixed, though I need to test it tonight on the turntable. I will also upload videos showing how that metal strip contact should work and the turntable working after.

Hopefully this is the end of my turntable troubles!


It is worth noting this issue has come up before and the below thread was of assistance - though Brakeman's issue was actually the exact opposite in that his was not making contact even with the slide engaged (ie. the metal strip was too far rather than making permanent contact)

https://www.marklin-user...a-Marklin-7286-Turntable
modelling era IIIa (1951-1955) Germany
Offline PJMärklin  
#10 Posted : 20 April 2018 06:59:28(UTC)
PJMärklin

Australia   
Joined: 04/12/2013(UTC)
Posts: 2,204
Location: Hobart, Australia
Originally Posted by: applor Go to Quoted Post
...I have been working on it lately and happened to notice that the track height between the bridge and spokes were of an unacceptable height difference. I must not be the only person with this issue?...



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UserPostedImage


UserPostedImage


UserPostedImage
thanks 2 users liked this useful post by PJMärklin
Offline applor  
#11 Posted : 20 April 2018 09:12:53(UTC)
applor

Australia   
Joined: 21/05/2004(UTC)
Posts: 1,652
Location: Brisbane, Queensland
edit: turntable works properly yay!

Edited by user 21 April 2018 13:23:53(UTC)  | Reason: Not specified

modelling era IIIa (1951-1955) Germany
thanks 1 user liked this useful post by applor
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