Digitrax PM42 Bachman Problem

[Brad Boxcar]

Thanks for all your replies and suggestions.

The odd thing is, every other locomotive I own - including a sound-equipped BLI Mikado - runs fine.  A friend even loaned me a new Bachmann RS3 and it works OK, just as my Bachmann 75-tonner does.  It's only the Bachmann FTs - all eight of them - that trip the circuit breakers.

Fortunately, I've kept all eight boxes that the FTs came in, so all nine of us are much happier now!

[rrinker]

 You've been told wrong. I put locos with Tsunamis and QSI and Loksound and yes, even an MRC all in the saem section of my PM42, shorted the track, and then removed the short. It recovered FINE, no stickign in shorted mode ebcause of the inrush. Peopel that say they have this problem have it with ONE sound loco in the section - I had FIVE in one section. I suspect they have marginal wiring and there is too much voltage drop. My PM42 is set on the default 3 amps per section, I might have changed the trip speed to one step faster, but that's about it. The only thing that ever gave any problem was, yes, Bachmann. Before I put the decoder in my 44 tonner I tried runnign it on address 00. It shorted the PM42. With a decoder and the capacitors cut, it's fine.

               --Randy

 

[retsignalmtr]

One of the members of the club i'm in had a problem with one steam loco, but only when he ran it at the club. As soon as he cracked the throttle the circuit breaker would trip on the PM 42 on whichever power district he had the loco on. Since the PM 42 was set to its default 3 amps I reset the current trip to 4.5 amps and that cured the problem. I have been told that the PM 42 is not good at absorbing the surge current drawn by some sound equiped locos. You might think of getting a solid state power manager like the PSX series.

[Lake]

I don't have any problems with engines and my two PM12's. It seems that it is most likely a wiring problem as Randy stated.

[rrinker]

 Any missed gaps, such that the sections aren't actually isolated? Or feeders that cross sections?

There's nothing specific in the standard line locos that should cause a heavy current draw at startup, they definitely don't have keep-alive capacitors like a sound decoder. They have kinda cheap decoders, with limited features, but nothign that should make the loco draw extra power.

 The only Bachmann I have is a 44-tonenr, it seems fine on my PM42, but I installed a TCS decoder, it's not the version that came with a decoder. I also removed the capacitors it had across th motor like all Bachmann locos, which greatly improved performance. Not much that the standard decoder does that would benefit by removing the capacitors - a better decoder with high frequency drive though is helped greatly.

                     --Randy

 

[Stourbridge Lion]

Brad - Welcome to trains.com!

[Brad Boxcar]

I installed a PM42 on my layout.  Hooked up sections 1,2,and 3 as circuit breakers (non- auto-reversing).  No. 4 is not rigged yet.  Everything seems to work OK . . . except for one thing . . . .

I have eight (8) Bachmann Standard Line HO FT diesels.  When I apply power to any one of them it trips the breaker.  This only seems to happen when I have more than one breaker wired up.  If I put the locomotive on the track in, say, Section 1 and disconnect the others, it runs OK.  

(Note: No locomotives on my layout are sound-equipped.)  

I've adjusted the trip amps and the speed. I've taken all locomotives off the layout except for the one I'm trying to start and it still trips the breakers.  As I said, every other engine runs fine . . . I can even put one of the FTs in the same section as another non-Bachmann and the non-Bachmann works fine.

Is there something in the Bachmann decoders, like a huge draw at the instant power is applied,perhaps?

My first thought was a defective locomotive.  But eight of them?  I can't see that, especiually since all eight run fine without the PM42 installed.

Any ideas?  Thanks