Microswitch

Dear Pos,

The Microswitches are the key, and the below takes longer to READ than it does to DO....

Step 1 - Wire the "C" terminal to the Frog
(Reccomend using Green wire...
...why Green? Because Kermit is green,
and maintaining wiring colour-code discipline will save your life)

Step 2 - Throw the turnout to a known position
(we don't care which way, whether it's "Normal" or "Reversed", "Straight" or Diverging", whatever,
just get it thrown in one direction)

Step 3 - LOOK and Establish for the currently-thrown position which rail should be feeding the frog
(Hint: The stockrail which is touching a switchrail is the one that should be feeding the frog at this time)

With the appropriate Stockrail known,
trace it down and confirm which of the "track buss" wires matches the Stockrail-in-question

Step 4 - Check the "NC" and "NO" switch terminals with a Digital Multimeter (preferrably in "Continuity" mode),
to establish which one is currently connected to the "C" terminal.

Step 5 - Wire a feeder FROM the appropriate Track Buss wire you confirmed in Step 3
TO the appropriate switch terminal ("NC" or "NO") you established in Step 4...
(Again, wiring discipline repays always, so use the correct feeder wire color for the Track Buss wire or "side")

Step 5a - ...and wire a feeder from the OTHER Track Buss wire to the OTHER of the switch terminals
(cue the familiar refrain RE wire color coding).

Happy Wiring,
Aim to Improve,
Prof Klyzlr

Saving the day

Prof you have saved my bacon and all kinds of electronic doo dads..lol..

I have a FLUKE  meter so checking as you instruct will not be an issue.

Understand on the color coding..especially the green.

My question here is should I wire both " C " terminals/micro switches to the frog or just one side/micro switch ?

Just 1 micro switch

Just use one of the micro switches for the frog power.

Consider the other switch as a spare or use it for panel indicator lights or signals or what ever.

Walthers Switch Machine Info and Recommendations

Although you can use just one of the microswitches, depending upon which turnouts you are using and how they are wired, i would recommend using both switches. The wiring is slightly more complicated, but the reasons are simple. Using both switches will make mechanical adjustment easier and will prevent any make-before-break moments (the servo moves just far enough switch one switch but not far enough to move the points which results in a short circuit). There is no reason to spare one of the switches as Walthers provides appropriate I/O (fascia, logic) through the board connectors.

Instructions and additional information is available on the Walther Layout Control System page and Walthers Switch Machine page.

Links from Switch Machine page:
Full Instructions

Instructions
 
Additional installation and operation information is available here:

Switch Machine Reference Guide - 01 Overview
Switch Machine Reference Guide - 02 Installation
Switch Machine Reference Guide - 03 Connecting Power
Switch Machine Reference Guide - 04 Options
Switch Machine Reference Guide - 05 Adjusting Throw
Switch Machine Reference Guide - 06 Connecting LEDs

Frog wiring for two microswitches

Connect frog to both C (Commons Black)

Connect tracks to NO (Normally Open Red) and NC (Normally Closed Blue) as per Prof Klyzlr's instructions.

Um, overkill?

Dear Ken,

I respect the knowledge and underlying "belt+braces+..." headspace,
but I can't help thinking that this is overkill. Leaving aside that I literally have never had a single-microswitch install mechanically or electrically fail in "pushed from the throwbar" installations
(and that's over 2 decades and more-than one-layout-worth-of-turnouts-so-wired per year,
or said-another-way, literally 1000s of turnouts in various scales/gauges/track-forms,
using any available common microswitches from no-specific manufacturer or source)...

Adjustment of which part of the "system"?
Is this an issue with the Walthers unit mechanicals/design, or something wider/more-basic?

I must confess to not having seen one of the Walthers units in-person, 
or completely comprehending how the mechanical linkage is connected to the microswitch lever arms,
(The switches seem mounted too-far-apart?)

but given the sheer ubiquity and simplicity of basic/inherrent microswitch operation,
I wanna file this under "...it can't be that difficult, can it?..."

If the microswitch used/supplied in the Walthers unit is a Make-Before-Break (MBB) switch,
then it's a poor choice of switch for the application.
(IE not the Users fault, that's a Manufacturer's component-choice/design/sourcing failure.

Interestingly, having personally bought loose microswitches in Aust, UK, and US at various times over 2+ decades, just walking into a store and saying "I want a microswitch" resulted in me recieving Break-Before-Make (BBM) switches in every instance, IE the "default"/"most-common" MS format on-request would appear to be BBM).

If however. if the issue is aleged that the short would (may) occur between
- track buss feed
- MS contact
- frog feed
- Frog
- frog linked by electrically-continuous Closure rail(s) to Switch/Point-rail(s)
- Switch/Point-rails making electrical contact with adjacent Stockrail
- track buss feeder

then I would note that any turnout wired and configured (gapped) so that the frog is completely-isolated,
a la Alan Gartner's "DCC Friendly" turnout,
(IE gapped from both both closure rails, and diverging rails),

Picture above posted with all respect and acknowlegment to Alan Gartner and the "Wiring for DCC" website  http://www.wiringfordcc.com/switches.htm

then there is no-way that the frog-feed could connect to the switchrails...
(and thus short thru the incompletely-thrown switchrail<> stockrail connection).

NB that this is distinctly root-cause seperate from:
- Operator stubbornly/blindly attempts to run-thru a turnout which is not set for the route
(Operator error)
- Turnout throw-system fails to properly mechanically and electrically throw,
leading to "appears mechanically-right, but is electrically wrong" fault condition
(Throw System Fault-condition, IE something is actually broke/mis-adjusted which needs fixin'.
It's not something that can be written-off as "a symtom of normal behaviour" on the part of the microswitch).

In short, "...if everything works the way it should, and typical components do...",
and the turnouts are wired "DCC friendly" as is the established proven method,
then cross-wiring the pair of microswitches feels redundant,
and slightly more confusing for the OP, where minimising-confusion would be the logical goal?

Happy Modelling,
Aiming to do my best "Willy Occum",
Prof Klyzlr

Powering the frog = short???

Thanks to the very informative description provided here by Prof (thanks Prof!!!), I thought I understood how to power my frogs using the Walthers switch machine.

Alas, I am doing something very wrong because the frog's power source is not changing to match the routing of the switch. 

First, a little background...

-I am using HO scale Fast Tracks turnouts that I have built and tested.

-I have enabled the Polarity Route option by connecting the appropriate pads with solder on the machine. I did this because it is my understanding that it is necessary in order to use a DPDT switch. I was using DPDT switches to power my previous switch machines and wanted to continue to use them.

-I have wired the frog to the "C" terminal of one of the micro switches.

-I have used my multimeter to find which terminal, "NC" or "NO", was connected to the frog and then connected those terminals to the respective buss wires. 

-With power applied to both the track buss and accessory buss, I can successfully run a locomotive through one leg of the turnout. When I throw the turnout to the other position, the locomotive shorts when it arrives at the frog. Some investigating with my multimeter has led me to believe that the frog is not flipping its power source when the turnout gets thrown. 

I am fairly sure I flubbed something up or am overlooking a step. I'm not sure, however, what the solution is. Does anyone have any ideas on what I could try to solve the issue?

-Colin

Pics?

Dear Colin,

I'm sad to hear that it's not playing-fair for you :-(

Any chance we can see some pics of:

- the wires as soldered to the microswitch

- the trace of the Buss/feeder lines between micro-switch and the Track Buss

- pair of images showing the machine thrown in each direction (want to see the interaction with the microswitch lever at each extremity)

- and a top-side pic showing exactly where the Four (4) iso-gaps are located, which isolate the Frog

My initial thoughts are that, while it is _possible_ that the microswitxh has failed internally,

(Incredibly rare in my experience, but it is an ekectro-mechanical device, and the laws of both Physics and Murphy have not yet been repealed),

It's _more_ likely that either there is some reason the microswitch is not-throwing completely,

OR

(and I say this for completeness, not as a personal dig)

Both "feeders" inadvertently got wired to the same DCC Track Buss line... (don't laugh, I've seen it happen all-too-frequently)

OR (Mystery Option #3)

there is something about the wider "Track array" context which we aren't aware of, which is futzing with the whole deployment (this turnout isn't part of a cross-over, reversing loop, or other multi-turnout array, is it?)

Rest assured, you/we _can_ sort this out, just gotta walk our way thru it methodically and diagnose appropriately...

Happy Modelling, 

Aim to Improve, 

Prof Klyzlr 

Pics!

Hello Prof!

This is one of the horizontal switch machines so pictures were difficult at times. I have done my best to capture the requested pics.

Here's the wires as soldered to the micro-switch...

Here's the trace of the feeders from the micro-switch to the track buss... 

Here's the pair of images showing the switch machine thrown in each direction...

And the top side viewing showing the four gaps (cut with jeweler's saw and filled with Fast Tracks StopGap Rail Gap Fillers) around the frog...

Let me know if there's anything else you might need from me (pictures and/or info).

Thanks for the help!

-Colin

Microswitch throw...

Dear Colin,

Thanks for the pics, a minor head-scratcher for sure! The pics certainly look like everything is "as expected",
(nice modelling BTW! Benchwork and turnout itself looks really nice, and the wiring is neat and disciplined.
It does certainy make diagnosing-from-a-distance a lot easier...   ),

but thinking about it over-night I'm prompted towards one thought. As a diagnostic recipe:

- Throw the turnout such that it is in the _broken_ (frog-not-switched correctly) state

Now, my _hunch_ is that this state has the relevant microswitch arm _depressed_ by part of the servo mechanism  (the "Long screw" in the manual?)

https://s3.amazonaws.com/aws.walthers.com/942-101+Switch+Machine+Instruction+Sheet+and+Advance+Control+Manual.pdf

Said another way, in this state, we WANT a connection between

C <> NO

but what we HAVE is

stubborn connection C <> NC

IF this is the case, proceed:

- Turn OFF the Layout, all Power gear, and anything that makes a sound in the vircinity.
I need your EARS to be Ultra Sensitive for the next step!

- Now, using a toothpick, kebab skewer, small screwdriver, whatever you have to hand that will fit,
press on the lever arm of the microswitch, and LISTEN CAREFULLY for a tiny "click".
You may (should, I suspect) also feel the level arm "give" a little as it "clicks".

If you have a multimeter handy, and can "jam" the switch in the "clicked" position,
(I hate describing it like that, but hopefully you understand what I'm suggesting),
I would hope that the frog now indicates _correct_ polarity for the selected route.

IF this is the case, then I Strongly Suspect that the issue is a mis-adjusted "long screw",
and/or the lever-arm on the microswitch is mis-adjusted. The Result is that the Microswitch is not being "fully thrown" (the threshold between "fully thrown" and "not quite" can be 0.00x" !),

and thus appears to stay-stubborrnly in a "C <> NC" electrical state.

Assuming you've gotten this far , and everything diagnostically is "as we suspect",
then the Solution would appear to be:
(in no particular order of preference, relevance, or appropriateness,
unfortunately I don't have one of these in-hand here to test in-person)

- see if it is possible to adjust the position of the "Long Screw" so that it sits slightly further out from the servo pivot point (I note that the Manual mentions loosening the Long and Short screws to adjust the Throw Wire, but unsure if this also affects the Long Screw <> microSwitch arm relationship)

OR

- power the layout ON,
throw the turnout AWAY from the "bad" position
(IE so that the microswitch is NOT engaged, encumbered, or interacting with anything)

- Power the layout OFF
(avoiding any electrical "whoops"s which could just compound an already-annoying situation)

and carefully, on the "free end" side of the "little red press-button",
bend the arm UP slightly, so it angles _further_away_ from the microswitch body.

The idea is,
- adjust the angles
- so that the Long Screw effectively pushes the key part of the lever,
(IE the bit that actually pushes "the little red button" and activates the switch),
down _closer_ to the microswitch body,
- thus achieving a "fully-thrown" mechanical state,
- and "clicking" over the "mechanical switching threshold"...

Obviously this would be easier if the unit was not "in-situ",
but from the pics, it appears _possible_ with a bit of strategic manipulation and modeller's-determination...
(we'll try to hold the "brute-force and ignorance" approach in-reserve until it's actually 110% required...   ).

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Success!!!

Hello Prof!

I am thrilled to report that after carefully following your detailed instructions I was finally able to get everything to work!!!

Your hunch was correct in that the long screw on the servo arm was not activating the microswitch. It finally activated after I gently bent the arm of the microswitch away from its body. 

Thank you for not only offering a variety of suggestions but also taking the time to walk me through the steps in a clear and concise manner. This is my first experience with microswitches (can you tell?!?) and I appreciated the opportunity to learn more about how to troubleshoot them.

Thanks again!!!

-Colin

Sorted!

Dear Colin,

Glad to hear you got it sorted!
(Cue "Hannibal" from "The A-Team"
"...I love it when a plan comes together...")

I'm prompted to note however:

1 - It's a pity that the unit was not approprately "calibrated" (QA tested?) ex-factory for appropriate throw and mechanical-interaction.

1.5 - A reading of the manual does not apparently cover such "out of specification" condition as a "Troubleshooting" condition.

2 - This is not a fault of the microswitch per-se, but rather,
the method of throwing the microswitch was "conceptually OK, not implemented/assembled with due diligence".
(The microswitch was OK, the mechanical servo throw/arm mech was conceptually OK,
to quote another classic, they just "...missed each other by that much...")

I've been a vocal promponent of Micro-switches for "bolt-on" frog-switching previously,
(half-throw the turnout,
push the microswitch against the throwbar or mechanicallly-related element til you just hear the "click",
hotglue/pin/screw the microswitch in place,
= Done! )

and not experienced the need to perform such post-install "lever bending", "throw calibration", or "adjustment".
(over 20 years, and as-many layouts, under both regular frequent-operation home and touring conditions, with zero failures to report).

That said, as part of my usual installation approach, I take specific care to ensure the mechanical-relationship and throw-distances/thresholds are correct from the outset. (see above).

...if only Walthers had "engineered in" the same level of "do it once, do it right, never have to do it again" ethos in the assembly/QA of their units...

Hopefully you've now picked up the practical skills and knowledge to go-forward and tackle your remaining installs with confidence...

Happy Modelling,
Can't wait to see more of your gorgeous layout!
Prof Klyzlr