I wired a Digitrax PM42 to my layout. I use the quarter trick to test each district and all work correctly when The red light on the PM42 lights up depending on the district. i.e. 1, 2 or 3 When I test a segment of my layout with a switch with my quarter the functionality of the "click" sound and the red light of the PM42 will not respond. Instead the lights of my passenger coaches get dim. When I glide my quarter across the rails of my layout within a certain district the PM42 lights up red and makes a clicking sound but as the quarter slides across a switch within "district 2" the PM42 stops responding as if it has not been wired to the PM42. From what I have observed with this test i8s that the switches has something to do with this issue and all of my switches are HO Atlas snap switches. What should I do to fix this issue?
Add more feeders. The dimming of the lights in the passenger coaches indicates that the quarter is taking a lot of power, but not all of it. That in turn points to some extra resistance between the PM42 and the quarter. Most likely, you have a loose rail joiner somewhere, and you're depending on that to transfer power down the track. By adding feeders, you will get around the rail joiner connection and provide full power to the section where the quarter test is failing.
The passenger car dimming note in your post, by the way, is a very good clue, the kind of thing us forum sleuths just love.
It takes an iron man to play with a toy iron horse.
I'll second MisterBeasley's opinion that you need more feeders.
After all, isn't that the purpose of the quarter test (it's not a trick): To test whether or not your short protection is working?
So, you need to add feeders anywhere on the layout where the quarter test fails to trip the PM42.
That crossed my mind, but I wasn't 100% sure. I will add more feeders then. Thanks for your help.
Let us know how it works out.
A good quick check could be done as follows:
Using a couple of jumper wires, apply power from the good section to the other side of the snap switch.
You can make a couple of jumpers with alligator clips to attach to your rails.
Or simple jam one end of a wire under a rail joiner, making sure it has good contact.Take the other ends and touch the rails in the bad area.
Now short across your rail with a quarter or similar conductor.
Its good practice to always attach feeders on both sides of a switch.
Jim
Could the switches be causing this?
alloboard Could the switches be causing this?
Since you are using Atlas snap-switches, the answer is no. They route power straight through both branches, regardless of the position of the points.
Yes, it definitely could be the problem.
While the Atlas turnouts are not power routing, they can cause a voltage drop. Looking at the switch, the two outside rails are solid. Obviously this cannot cause a problem.
The inside ones can develop excessive resistance. The pivoting rivet could be the cause. That is why feeders are important on both sides of the switch.
As I recall, Atlas turnouts actually have jumpers on the underside of the turnout to bypass any gaps. The points do get power through that rivet, but there is an internal hard-wired connection between point-end rails and the rails beyond the frog.
Best way to make sure those switches are passing enough current is to solder feeders to the stock rails. Don't depend on the rail joiners between the switch anmd adjacent rail. You could also just solder the rtail joiners but feeders make teh swit6ch easier to change out in teh future if needed.
Martin Myers
MisterBeasley As I recall, Atlas turnouts actually have jumpers on the underside of the turnout to bypass any gaps. The points do get power through that rivet, but there is an internal hard-wired connection between point-end rails and the rails beyond the frog.
Before I get into this, let me say that Atlas is without a doubt one of, if not the best model railroad company. The Atlas snap switch is very durable and I have many on my 4x8 layout. I am not trying to imply this happens on every snap switch. I cannot comment on other brand switches except Life-Like and Tyco, both of which were complete junk.
The Atlas turnouts have jumpers but a problem can develop.
Shown above is the value of a outside rail. A nice low 0.2 ohm resistance value which we would expect. If we checked the other outside rail a similar value would be measured.
Shown above is one of the center rails. 10.13K ohms. Its hard to see but that is definitely a K next to the ohm symbol. This is very extreme case. I have measured others with much lesser values.
Shown above are the jumpers between inside, outside and the rivet. This is the only jumper between the inside and outside rails.
The Atlas snap switch relies on this piece of metal which spans the gap between the outside and inside rails. It is attached to the rivet which is used to pivot the point.
As shown above, the problem is the jumper is not spot welded or soldered to the 2 rails.
Note how I have pivoted the RH one. It is placed under a tie, which I have removed for illustration purposes.The plastic tie is what locates and holds the jumper in place.
With the tie removed, the only physical connection to the switch the jumper has is the rivet.
Why does the excessive resistance happen? Once the rivet loosens, the jumper flex's and resistance builds. The lack of a solder / spot weld lets the jumper flex. Contamination from water and glue could also be an issue but I do not ballast in that area.
If you have feeders on both sides of the switch, you will never know this has happened. Power will be supplied from the other side and will travel right up to the rail before the rivet. You could run a better connection with a wire jumper and solder but it is easier to just run feeders on both sides.
While we do not know for sure the OPs problem, this could potentially be the cause.
I really appreciate how you people have dedicated your time and effort to provide such informative resources. All the power problems I had has been fixed. Thanks to your help.
Very interesting and creative, thanks for your effort.
Your welcome, glad I could help.