Digitrax Issue - "singing" moving between main lines

[altohorn25]

I've been in contact with customer support at Digitrax for the past few days, but we've been unable to rectify the issue.

I have a medium sized n scale layout.  I have a double track mainline using Atlas code 55 track and turnouts that has about 10 crossovers scattered throughout in order to move from one main to the other.  Each of these of course has insulated rail joiners linking the two diverging rails of the turnouts at the crossover so that there is no short. 

I have a DCS240+ as my command station.  This is wired into the Eastbound main and all the spurs that come off of the Eastbound main.  The Westbound main and associated spurs is powered by a DB220.  Both the command station and the booster are powered by a Digitrax PS-2012E - power wires are the supplied power wires with the interline circuit breakers.

Here's the issue:  when I move a locomotive from one main line to the other main line, it "sings" when the locomotive wheels bridge the insulated rail joiners.  In addition to this audible "singing", the amp meter on the PS-2012E moves up about 1 Amp from normal.

The Digitrax people initially thought that I needed to trim the voltages on either the Command Station or the Booster because one of them was lower or higher than the other.  Using a multimeter, I measured the current and found that the Command station was a little less than the Booster.  I adjusted the Command station to compensate so that I got the same reading of output from both units.  The "singing" problem persisted.

Digitrax then thought it was my wiring of the crossover turnouts.  I don't believe this is the issue because when I use the Command station to power both mainline busses, I have no problem moving over the crossovers between the mainlines.

I don't want to fry decoders with the small spike in Amps moving between my mainlines (which I have to do on a regular basis....especially coming out of the staging yard).

Here is a photo of my setup (yes.....I need to build a shelf so that the units are not sitting on cardboard boxes.....on my short list of things to do).

[ Guests cannot view attachments ]

Anyone have any ideas?  Your assistance would be greatly appreciated.



Nate

[eja]

What song, man?


(Sorry, I know that's no help.)

[skytop35]

Sounds like the rails are not in sync between the mainlines. Try switching The Rail A and Rail B wires on either the DCS 240+ or the DB 220 but not both.

[altohorn25]

Sounds like the rails are not in sync between the mainlines. Try switching The Rail A and Rail B wires on either the DCS 240+ or the DB 220 but not both.

I tried that; get a dead short when I do that.

On a similar note, the polarity of the power leads going into both the command station and the booster are the same as per the instructions from Digitrax.

[skytop35]

Are the Command station and booster grounded together?

[John]

I don't have either of the units -

1) Make sure you have a ground wire between the command station and the booster
2) Make sure the booster is not set to be a command station
3) You said you have one run the entire layout with one unit .. that seems to imply that you don't have any separation between the two "tracks" or "power districts" .. it would help to see a track diagram with your power districts laid out

[John]

You might not need to run the entire layout with two boosters ..

One other thing to test .. put a continuity tester between the rails of the east bound main and the west bound main .. (same track to same track) .. if you get a sound .. then you probably have a cross connect between the tracks and the boosters are working together

A ___________
B____________

A____________
B_____________

Measure A to A, B to B

[altohorn25]

Are the Command station and booster grounded together?

Yes - as per the Digitrax manual, the red power leads go into the + terminal on the Command Station and the Booster, while the black power leads go into the GR terminal on the Command Station and Booster (not the - terminal).

[altohorn25]

I don't have either of the units -

1) Make sure you have a ground wire between the command station and the booster
2) Make sure the booster is not set to be a command station
3) You said you have one run the entire layout with one unit .. that seems to imply that you don't have any separation between the two "tracks" or "power districts" .. it would help to see a track diagram with your power districts laid out

The two mains only contact each other at the crossovers between the mains.  Each of those crossovers has insulated rail joiners to isolate the two main lines.  Each main line has it's own set of bus wires.  When I tested it using only the Command Station to power both mains, I just twisted the leads the run to the main power busses together so it was essentially all one loop.  No "singing" going across the crossovers when I did that.  It only happens when I try to use the Command Station on one main and the Booster on the other main.

I'm pretty sure the DB220 can't be a command station, but I will check the manual for that.

[altohorn25]

You might not need to run the entire layout with two boosters ..

One other thing to test .. put a continuity tester between the rails of the east bound main and the west bound main .. (same track to same track) .. if you get a sound .. then you probably have a cross connect between the tracks and the boosters are working together

A ___________
B____________

A____________
B_____________

Measure A to A, B to B

I'll go to the hardware store tomorrow and get a continuity tester and see what it does.

[John]

nate... if you have a cheap volt ohm meter .. you can use that ..

https://www.wikihow.com/Test-Continuity-with-a-Multimeter

[altohorn25]

So.....I have a work-around, although the problem might still be there (somewhere), this is working for now.

Talked to Bill Denton on the phone a bit this morning and he suggested to use the DCS240+ as just the "brains" and run the two mainlines (power districts) off the DB220.  The DB220 has individual jacks on the front of it for two power districts (essentially my two main lines).

I hooked up the bus wires to the DB220 (one main to R1A and R1B and the other main to R2A and R2B).  Now when I run a locomotive over the crossovers between mains (power districts), there is no "singing" and no spike on the Amp meter on the PS-2012E.  I can do the quarter trick on each mainline (short the main) and the other mainline continues to function properly with the one mainline being shorted.

Perhaps it goes back to the voltage trim not quite being the same between the command station and the booster (we're talking a few milliamps here....), but I'm really not sure.

Long story short, the concert is over for now.  The fat lady has left the building and everything appears to be working properly.  No more "singing." 

Thank you for everyones' suggestions.  I appreciate the help.

Nate

[John]

Good to hear Nate .. That's a good solution .. but it's worth while to still troubleshoot the issue ..

One quick test with your new configuration.  Disconnect one of the two power district cables from the DB220 and see if trains will still run on both mainlines .. that should tell you if there is a possible interconnect between the two .. I've on occasion mixed up my power drops when wiring up the layout . .

Good luck

[altohorn25]

Good to hear Nate .. That's a good solution .. but it's worth while to still troubleshoot the issue ..

One quick test with your new configuration.  Disconnect one of the two power district cables from the DB220 and see if trains will still run on both mainlines .. that should tell you if there is a possible interconnect between the two .. I've on occasion mixed up my power drops when wiring up the layout . .

Good luck

John:  I will try that.  Good idea.

[altohorn25]

Good to hear Nate .. That's a good solution .. but it's worth while to still troubleshoot the issue ..

One quick test with your new configuration.  Disconnect one of the two power district cables from the DB220 and see if trains will still run on both mainlines .. that should tell you if there is a possible interconnect between the two .. I've on occasion mixed up my power drops when wiring up the layout . .

Good luck

John:  As expected, when I disconnect one of the wires from the DB220, trains only continue to run on the other main.  Tried it on both mains and the same result.  No direct power from the booster results in no trains running on that main.  No interconnect between the two mainlines (power districts)  So in my head, there doesn't appear to be any "cross wiring" of feeder drops running to the busses.  FYI:  I used black and  red wires on one main and yellow and blue wires on the other main to help keep track of that sort of thing in the first place. 

I'm still at a loss about the original issue, but this is working........guess I'll live in ignorance......