 Joined: 19/09/2022(UTC) Posts: 459 Location: Kaarina
|
Hi,
I’m experiencing a strange issue on a section of K track. Locos don’t run on a about 40cm section in the middle of flex track.
I’ve checked continuity with multimeter from a section where locos do run. All center studs in the section have continuity as does rails (this is in the middle of flex track…). The section however does contain two contact track sections that have been cut from the other rail.
I’ve also checked the voltage with multimeter, the reading is 21 volts.
But locos don’t run.
I’d be grateful for some ideas on what to check next?
Best regards,
-Eino
|
 1 user liked this useful post by einotuominen
|
|
|
|
 Joined: 10/02/2021(UTC) Posts: 3,889 Location: Michigan, Troy
|
I've also cut K track, and experience current loss on it at times. The joints don't have much allowance for temperature contraction or expansion.
|
|
|
|
|
|
 Joined: 04/02/2011(UTC) Posts: 3,563 Location: Paris, France
|
Hi Eino
Checking with multimeters is very fine but they fail on one thing: checking the real available power. You are measuring the voltage WITHOUT current. This is because their high impedance (typically 20,000 Ohms/Volt) compared with that of a loco (a few Ohms).
K-Track, when ballasted are famous for contact issues. Why? Because the liquid glue used to attach ballast corrodes contacts and especially the central studs.
On a flexible track, central studs come from a one piece of flat soft iron. At the extremities, you have a contact piece with 2 forked contacts. So between 2 flex. track stud connection is made through three consecutive contacts and it takes only one being faulty to have troubles.
You measure 21 volts but still locos don't run?
Either there is an unwanted resistance (poor contact) in the feed system that makes the voltage to go to near zero when there is a real load (a few watts)
Or, only one the rails is powered (very common as many of us use occipancy detection) and so on short locos with few axles - some of which may have traction tires - causes issues when pick-up wheels and rails get "contaminated" (grease residue with decaying traction tires).
What is the cure? Replace wet ballasting with dry one (Merkur etc). Repair faulty contacts with soldering (studs can be soldered rather easily, rails can be soldered using "soldering water" ON A CLEAN SURFACE.
My own experience? Use C track which is way better for contacts, better switch mechanisms and excellent aspect when you paint the rail sides and ballast the side of the rails. K track dates back from late 70s and has never been really improved.
Cheers
Jean |
|
3 users liked this useful post by JohnjeanB
|
|
|
|
 Joined: 11/07/2018(UTC) Posts: 217 Location: Aruba (general), Oranjestad
|
Eino
I also use K-track and flex rail.
Does the lok simply stop and don't move at all or does it slow down and stops running (lights are still on but dim)
In the second case, there is most probably a bad connection causing insufficient current to flow.... you can find out where the point of high resistance is by touching the spots where the track sections join... they will feel warmer at that spot...
In the first case, are you sure the return path (outer rails) are connected? Unlike C-track the outer rails are not connected to each other by design, so if you have contact track sections, make sure the opposite side of the cut track is still connected to the return path ("ground")
Regards
Jean-Pierre
|
1 user liked this useful post by cintrans
|
|
|
|
Joined: 04/02/2021(UTC) Posts: 480 Location: USA
|
Originally Posted by: cintrans  Eino
I also use K-track and flex rail.
Does the lok simply stop and don't move at all or does it slow down and stops running (lights are still on but dim)
In the second case, there is most probably a bad connection causing insufficient current to flow.... you can find out where the point of high resistance is by touching the spots where the track sections join... they will feel warmer at that spot...
In the first case, are you sure the return path (outer rails) are connected? Unlike C-track the outer rails are not connected to each other by design, so if you have contact track sections, make sure the opposite side of the cut track is still connected to the return path ("ground")
Regards
Jean-Pierre
I did not realize the latter, that K outside ground rails are not connected. I assumed that K was same as M and C for digital AC. In that case, axles-return contact becomes as finicky with K as with Z (=DC). Rails must be kept very clean to work properly. |
|
|
|
|
|
|
 Joined: 28/11/2007(UTC) Posts: 8,226 Location: Montreal, QC
|
There is a simple explanation for this. On K Track, the two outer rails are isolated from each other. The only link that joins them are the feeder track and the axles of the trains*. If you cut the rails for contact purposes, this means that the locomotives need to use the other rail for return and if your rails and wheels are not extremely clean, this makes the locomotives vulnerable to power loss.
What you can try is to solder a wire bridging the two rails in the sections not used for contact, so that the trains can use both rails for return. It is also important to ensure that the rail joiners form a tight connection so that there is no weak spot between track sections.
* Switch tracks also provide contact between the rails except for certain spots.
Regards
Mike C
|
2 users liked this useful post by mike c
|
|
|
|
Joined: 19/09/2022(UTC) Posts: 459 Location: Kaarina
|
Hi,
Excelent points!
Wiring for both rails is in order. Actually the K track section is connected to C track from both ends so grounding is good.
Jean makes a good point. I actually bought the tracks 2nd hand used. Although they look to be in good shape, there actually was some glue residue on the center studs.
The solution? I took a very fine file and filed the center studs back and forth only two times and the residue is gone. Locos now run perfectly!
Amazing.
Thanks!
BR,
Eino
|
2 users liked this useful post by einotuominen
|
|
|
|
Forum Jump
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.
