Megapoint Controllers

[Gordon A]

I'd rather have no cross board wires but I've had to compromise with DCC+ and DCC-

 

I have used the bolts that bolt the boards together with a bit of elctrolube to good effect.

 

Gordon A

[Ian Fisher]

Just getting my head round a first install with this fine system.

 

We had a few sessions of installing them adding a few points in, then tonight we went for twelve, we then starting having a few servos buzz and then the system would seemingly shut down after nineteen seconds or so.

 

We then started taking leads out to see what if any connections might of been ropey.

 

Have we gone west someway?

 

ideas gratefully received

 

Ian

[unravelled]

Have you contacted Megapoints directly. They wre very helpful when I had problems starting out with the controller.

 

Dave

[gismorail]

Have you contacted Megapoints directly. They wre very helpful when I had problems starting out with the controller.

 

Dave

Would second that really cracking people and helpful . He would be cross if you did not contact him to be honest if your having problems

[Gordon H]

Sounds to me like an inadequate power supply - a common problem with multiple servo systems.

Twelve servos can take a lot of current, especially at switch on.

[njee20]

Sounds to me like an inadequate power supply - a common problem with multiple servo systems.

Twelve servos can take a lot of current, especially at switch on.

Agreed. I had this - I'd get to a point where all the servos would twitch in unison when starting up and not respond to input, but indiscriminately unplugging them would fix it. The board requires quite a bit of juice on start up once you get up to 12 servos, and need at least 2 amps IIRC.

 

I bought one of the 15A power supplies recommended on the MegaPoints website, which has proved excellent, although It has a fan in akin to a PC, so my layout is now a little nosier!

[Ian Fisher]

Thanks for all the replies so far,

 

We get how good the system is and have had feedback from Dave too.

 

I was am interested in seeing what others have and are doing with the system.

 

The low power thing could be something too in an attempt to safe guard the system at first we were running slightly turned down ( we have a test unit from Maplins which has a slide setting providing a range of settings.)

[Gordon H]

 

The low power thing could be something too in an attempt to safe guard the system at first we were running slightly turned down ( we have a test unit from Maplins which has a slide setting providing a range of settings.)

 

When you say 'turned down', I presume you mean the voltage?

Usually it is not the voltage that is inadequate, it is the current that can be drawn from the supply.

Servos can take quite a bit of current each, especially when driving a load. To minimise build up of the effect, it is critical that the servo endstops are set so that it is not continually trying to drive against an immovable object at each end. You will soon know if this is the case because the servo will seem to 'buzz'.

One way round it is to disable the pulse drive after the servo has moved to its new position, but this requires the servo controller to have that facility. I don't know if the Megapoints driver has that capability. On some (e.g. MERG Servo4), it is an option you can select.

Edited July 4, 2016 by Gordon H

[Ian Fisher]

When you say 'turned down', I presume you mean the voltage?

Usually it is not the voltage that is inadequate, it is the current that can be drawn from the supply.

Servos can take quite a bit of current each, especially when driving a load. To minimise build up of the effect, it is critical that the servo endstops are set so that it is not continually trying to drive against an immovable object at each end. You will soon know if this is the case because the servo will seem to 'buzz'.

One way round it is to disable the pulse drive after the servo has moved to its new position, but this requires the servo controller to have that facility. I don't know if the Megapoints driver has that capability. On some (e.g. MERG Servo4), it is an option you can select.

 

Hi Gordon,

 

Yes I did mean the voltage and yes we have had buzzing too. We are again following a lead from Dave and will see how this will work.

 

away from the layout things are ok do the same sequence on the layout erm.

 

Are we ok to just centre the servos manually or do we have to do this off the layout?

 

We want this to work!

[Suzie]

Only run on low power when testing with a single servo connected. The lower the voltage the more current the Megapoints will draw. With all the twelve servos moving at startup they will take about 10A at 5V, which equates to 4A or so at 12V. If you do not have sufficient power available (either current or voltage) the servos will never get to their start position and maximum available power will be drawn constantly which is not a good thing. This is one of those scenarios where restricting the power is likely to cause harm rather than be protective.

[Ian Fisher]

Only run on low power when testing with a single servo connected. The lower the voltage the more current the Megapoints will draw. With all the twelve servos moving at startup they will take about 10A at 5V, which equates to 4A or so at 12V. If you do not have sufficient power available (either current or voltage) the servos will never get to their start position and maximum available power will be drawn constantly which is not a good thing. This is one of those scenarios where restricting the power is likely to cause harm rather than be protective.

 It would seem that this was part of our issue.

 

We have a supply that runs 3A at 12v variable...

 

Tonight ​have ​been able to reset a board and finally add in a number of servos away from the layout once again and go back to ones we want in turn to zero them and then do a hi low, I think we may have been in a rush to get stuff further along than we were able.

 

We then maybe got ahead of ourselves in installing a board full at a lower amp than we shouldve which then gave us further issues.

 

I think we have turned a corner! 

[AndyID]

As Gordon H points out, servos will buzz if they are trying to get to a particular position but can't quite get there because of mechanical limits. One solution to this is to have some compliance (a spring of sorts) between the servo and the turnout.

 

Buzz can also result from electrical noise that is coupled into the the controller or to the servo itself (or both). This noise results in a difference jitter between the width of the pulse from the controller and the width of the internal pulse that represents the position of the servo. If the jitter is great enough, the servo will continually try to cancel out the difference and buzz. One way to find out if it's caused by power supply noise is to run off batteries during a test.

 

Random servo twitch is caused by noise coupling into the signal input of the servo. This might be caused by long cables and/or powerful electrical noise generators. Anything that can produce an arc (such as dirty track) is a potential culprit. It might be necessary to use shorter cables and more controllers to eliminate this. Routing the servo cables parallel to other cables (track feeds etc.) in neat bundles might be exacerbating the problem.

[Ian Fisher]

Help!

Still struggling to install Megapoints on a layout , it's a case of one step forward two back !! Anybody around the Burton on Trent /Derby/Uttoxeter areas able to help?

[AndyID]

Help!

Still struggling to install Megapoints on a layout , it's a case of one step forward two back !! Anybody around the Burton on Trent /Derby/Uttoxeter areas able to help?

 

I would if it wasn't quite so far.

 

What sort of problems are you experiencing?

Edited July 19, 2016 by AndyID

[RodneyV]

I've used one in my latest layout due to their value and ease of use. They work really well although the servos do 'twitch' occasionally which some may find annoying but apart from that they work perfectly. For changing the frog polarity i've wired the frog and servo to both be controlled by a DPDT switch which seems to be doing the job fine,

 

Gary

 

Hi Gary,

 

Could you post a picture of the DPDT switch you are using in position if possible please. I'm curious to know what type of DPDT switch you are using and how it looks.

 

I recently have bought the MegaPoints starter pack and will start using them (experimenting) soon.

 

Thanks and Regards

 

Rodney V

[Vecchio]

I was visiting the Warley exhibition in 2015 - wasn't planning to spend much - but went home with a megapoints controller start set.... What Dave showed here was exactly what I wanted. As this was the time I decided to build a new layout it was the right time to buy the controller. In the meantime I have purchased a few more components, I am now a 4 megapoint controller boards, I had to purchase the switch and led extension for the mimic board (Led extension x 3 as I like to see 2 leds for the point position on my mimic board). Also I purchased relay boards as I want to stay lean with the cable connections between mimic board and layout.

 

About servo buzzing: There will be always some servo buzzing, it depends mainly on the servo itself. And we will not be able to avoid a slight force on our servos when we want to be sure that the point blades are properly set. I don't know how the others are doing it, I personally remove the spring from Peco points and use a very thin steel wire (0.4mm) from the servo to control the point. This way it is possible to use the wire itself as a spring force. I run the servo very slightly over the necessary position so that the wire acts like a spring. It is not as strong as the peco spring but it works. Of course I do not rely on electric connections done by the blades but wire them all. And after that we have a second constant force to our servo - most of you will use miniature limit switches to wire the frogs or also to switch off a section of track before the point to avoid short circuits. These are rather nasty - especially when you use DCC...

As these limit switches have a spring you have another load to the servo. And these forces together with the limited precision of the servo are for me the main sources for the servo buzz. And be careful - don't use digital servos. They cost more and the servo buzz is normally worse than with analog ones.

 

So far to my experiences - one of 4 modules is now wired, all works fine and I enjoy a 5 wire connection between layout and mimic board.

 

Now some questions for the community: How to wire properly the leds on the mimic board for 3-way points??  In good old analogue days I just made an and logic with relays and the thing works. And now? the second point in the 3 way point should only light the led when the first point shows straight. How to do that? Dave answered me to buy the route processor - no way. I spent already a lot of money and I think it is not the solution for the problem. Any ideas?

 

Second problem: Light signals. I spent a lot of money for authentic OBB signals which can show you 2 different speeds, but also the departure signal. I am not to sure how to do it. It will need a lot of channels. By the way - the relay board sold by Dave is an Arduino board - the megapoint controller works also wit 6 or 8 relay channel arduino boards. How do I know? just purchased an arduino board on the net....

 

All in all I am still happy with the system and I am still learning stuff about it. See below the mimic board built for Donnersbachkogel

IMGP5432 by Gerhard Novak

 

Standard way how I install the servos. here with 2 auxiliary contacts. On the top of the picture is the Lenz connector board for my DCC controllers. Old fashioned - as it uses cables...

20160625_203950[1] by Gerhard Novak

Edited July 19, 2016 by Vecchio

[Ian Fisher]

We have added a new power source and from advice from megapoints will be looking to investigate the extension leads.

 

I get its a process of going through the things

[Ian Fisher]

We have added a new power source and from advice from megapoints will be looking to investigate the extension leads.

 

I get its a process of going through the things

Edited July 20, 2016 by Ian Fisher

[Ian Fisher]

Edit

[Modelling Martin]

Hi Gary,

 

Could you post a picture of the DPDT switch you are using in position if possible please. I'm curious to know what type of DPDT switch you are using and how it looks.

 

I recently have bought the MegaPoints starter pack and will start using them (experimenting) soon.

 

Thanks and Regards

 

Rodney V

 

Hi Rodney

 

Mine work by switches on a panel:

 

 

 

If you look underneath at a switch (number 1 for example) the first column has two black wires, one wire is the common from the Megapoints board (centre row) and the other is the wire that goes into the switch connector on the Megapoints board. The middle column I've left empty so I could attach LEDs to them at a later date for route indication. The final column has the orange and grey wires in the top and bottom row which is the track feed (+ and -) with the centre (white / green wire) being the frog for the point. The number of wires is just because there is a lot of points as the process is repeated for every point. The frogs connect to the control panel via VGA cables,

 

Hope it makes some sense,

 

Gary

[Vecchio]

Hi Rodney

 

Mine work by switches on a panel:

 

IMG_6614.jpg

 

IMG_6616.jpg

 

If you look underneath at a switch (number 1 for example) the first column has two black wires, one wire is the common from the Megapoints board (centre row) and the other is the wire that goes into the switch connector on the Megapoints board. The middle column I've left empty so I could attach LEDs to them at a later date for route indication. The final column has the orange and grey wires in the top and bottom row which is the track feed (+ and -) with the centre (white / green wire) being the frog for the point. The number of wires is just because there is a lot of points as the process is repeated for every point. The frogs connect to the control panel via VGA cables,

 

Hope it makes some sense,

 

Gary

 

Hi Gary,

 

I understand you are using the Megapoint controller without their mimic panel. This means you have a large number of wires coming out of your panel and the need of several connectors - I can see 2 D-sub and also several others. For me one of the advantages of the Megapoint system is the bus - means I have only 3 data and 2 power connections - means with one 5-pole cable I can go out of the mimic panel - and I leave the controllers under the board - close to the servos. This also allows me to connect direct - without extension - in case of a station where you have many points in the same area.

This is how I fix the controller below the board.20160625_204012[1] by Gerhard Novak

 

In this case the controller shares the box with a relay card as I have some switch applications on the module like lights and light signals. There is a transparent lid on it, which holds the cables in the little cut slots. And - not to forget - there is also an external voltage regulator - glued to the wall close to the relay card - as the relay board draws too much current for the built in voltage regulator (Dave describes this in his documentation)

The devices using the relay card are not yet wired.

On the left corner you see the power supply for the whole system (everything except the DCC which has its own transformer) - it is an RC power supply from fusion delivering 100W - or approximately 7A (but with some fan noise).

Edited July 21, 2016 by Vecchio

[RodneyV]

Hi Rodney

 

Mine work by switches on a panel:

 

IMG_6614.jpg

 

IMG_6616.jpg

 

If you look underneath at a switch (number 1 for example) the first column has two black wires, one wire is the common from the Megapoints board (centre row) and the other is the wire that goes into the switch connector on the Megapoints board. The middle column I've left empty so I could attach LEDs to them at a later date for route indication. The final column has the orange and grey wires in the top and bottom row which is the track feed (+ and -) with the centre (white / green wire) being the frog for the point. The number of wires is just because there is a lot of points as the process is repeated for every point. The frogs connect to the control panel via VGA cables,

 

Hope it makes some sense,

 

Gary

 

Hi Gary,

 

Thank you for your response.

I misinterpreted what you said originally. I thought you had a DPDT switch next to the servo instead of attached to the control panel.

I was interested in seeing a DPDT switch attached at the servo and how you did it. I thought this might simplify the installation of frog and LED control.

 

Thanks again

 

RodneyV

[Vecchio]

Rodney,

what you need on the servo is a limit switch. These are small, non expensive but precise switches which have normally a long lever. Limit switches cost less than a pound and normally have 3 contacts - common - position on - position off. See below the use of a limit switch attached to a servo. DSC03027 by Gerhard Novak

[RodneyV]

Rodney,

what you need on the servo is a limit switch. These are small, non expensive but precise switches which have normally a long lever. Limit switches cost less than a pound and normally have 3 contacts - common - position on - position off. See below the use of a limit switch attached to a servo. DSC03027 by Gerhard Novak

 

Hi Vecchio,

Thanks for the photo and information.

Regards

RodneyV

[AndyID]

We have added a new power source and from advice from megapoints will be looking to investigate the extension leads.

 

I get its a process of going through the things

 

Did you get it all sorted out?