Dash 9 had its melt down on the C line, but others went bad on the A and B line. With the booster not shutting down at all, guess it did not matter which line the engine was on if there was a problem.
Cuda Ken
Yep, if your booster isn’t kicking out on a short then it wouldn’t matter which line or what size wire you have, something is going up in smoke. This is where some type of external current limiting protection can help.
I thought it might be a wiring problem. I had the same thing going on with my Bachmann booster until I changed the buss wires from 18 gauge (the layout was originally wired for DC) to 14 gauge. Before it would take a couple of seconds for the system to shut down. Sometimes it didn’t shut down at all. If I short the track now it shuts down immediatly which is what it’s supposed to do.
Very good news!
I’d still break things into current limited districts. You really have no reason to want to allow the possibility of 8A through anything, even for a short time. Actually, I would not be shocked it you could get rid of 8A booster entirely, not that the wiring is better.
Jeff, the only reason I bought the MRC 8 Amp Booster is I was told by some here a few years ago it would work and simple to hook up. Bachmann 5 amp booster was $150.00 and I bought the MRC new for $120.00. Main selling point was when I talked with a person at MRC, was told it would work with ALL DCC system including Digitrax Zepher. One of the things that held me back from buying a Zepher was I was afraid its 2.5 amp power supply would have to be up graded latter.
2 years later I am final dollar wise able to make the jump to a different command station. When I get the new house and build a 400 plus feet of track bench it will be used again. Will have 5 mains, and then a few short branches.
Cuda Ken
With time and use comes valuable experience. I’ve learned a lot about DCC in the past few years. I find the 2.5 amps of the Zephyr to be sufficient for most of my needs. The 5 amp booster cuts in when I need extra power. I wouldn’t mind having a bigger layout but unfortunately the trailer isn’t big enough for that.[(-D]
I would get the Zephyr, Ken. Not the Super Empire Builder. You can’t ready CV’s with the SEB, although with a PR3 away from the layout you could. 2.5 amps is probably plenty, and when you get to build that bigger layout you can add on as needed, always having the use of the Zephyr. It’s a different mentality with Digitrax - you just add on what you need when you need, never throwing out the old stuff. It all keeps working together. Kinda of like adding power to your car by adding a blower instead of changing out the motor.
–Randy
Ken, my point was that I never thought you should need any booster at all. There’s nothing wrong with having a big booster, except that you then need to be more careful about limiting the current to the track. Which is where either breakers or bulbs come in.
I reasoned that the problem was in the wiring. The thing to remember is that a short circuit may not actually trip a breaker or blow a fuse. You can have more than enough current flow to damage something without blowing a fuse.
If the wiring is sub-standard, the voltage drop the occurs will at some point be a real problem. According to Kirchoff, if the voltage goes down, the current must go up, to maintain the power. When that happens, something gets destroyed.
A good example is power tools. The instructions always warn about extension cords, recommend the gauge and maximum length you should use. Ignore that, and you will void the warranty when the motor burns out. Too much current draw, end of motor.
Something to protect the circuit from excessive current flow is a good idea. Poor wiring will defeat the circuit breaker in the booster, because it doesn’t use the amount of current, but the rate of change to determine something is wrong. Too much resistance will reduce the effectiveness, to the point of rendering the circuit protection useless.
Adding one those light bulbs in series is a bad idea. It makes good wiring into substandard wiring by introducing resistance. It will limit the rate of change, and defeat the circuit protector. There is still more than enough current flowing to damage something. That is a relic of the DC age, and needs to be forgotten about. Big difference between a 2A DC circuit and an 8A DCC circuit…
For the purposes of this discussion we can assume the output of the booster is constant up to its rated output current of 8A. I am with you on your first paragraph but on the second paragraph, if the wiring is substandard to the point where the overall resistance is high enough to reduce the amount of current across the short, then current drops and doesn’t go up because the source voltage is constant. Now if you are referring to the short itself (in this circuit) then this is correct, less resistance means lower voltages which means higher current but this would happen with better wiring not worse wiring. Worse wiring would actually deliver less current across the short due to the higher resistance of the wire and subsequent voltage drop across the substandard wiring.
The other part of the equation is the protection circuit. You are right on target in the 4th paragraph.
At this point I going to leave the two brains to debate this part. I am just happy it shuts down when needed and nothing has melted.
Anyone need any taillights?
Ken
Sounds as if you’ve corrected your problem. Melted wiring can be scary and expensive.
You didn’t corner the market, did you?
Next time buy a car made in America with a decent reliability record. Maybe something like HONDA or TOYOTA LOL. Then instead of knowing your mechanic by his first name, you’ll be able to afford those nice things.[:)]