My new N scale layout is powered with Digitrax DB150 and I bought a new Digitrax PM42. The layout has 2 reversing loops and a wye in the middle of one of the loops that goes to my DCC turntable, I can't figure out how to wire the PM42 into the layout. I would post my track plan, but I can't figure that out either. I did manage to upload a photo of it in the Photo Gallery though. The D&SRR. PLEASE take a look and see what you guys think.
I don't see any photos posted by you in the Photo Gallery. Do you see it up there?
Rich
Alton Junction
The Instruction sheet that comes with the PM42 has a diagram on page 8 that tells how to wire it into your system. Don't forget that BOTH ends of your reversing loop have to be gapped ( Insulated ) on BOTH rails and the power from the one set of terminals on the PM42 that you are using as the reverser have to be connected to that isolated loop.
If you don't have the instruction sheet go the Digitrax website, click on Products, then Power Management, then PM42 then Instruction Sheet in the top right corner and scroll down to page 8.
First time figuring it out sometimes takes a while, but when its done make notes and the second one will be easier.
Kay.Div.
You can use the same set of terminals from the PM42 to also power another section of track but at our club we have the reversing section as a seperate section. It SHOULD be easier to figure out where any short circuits are that way as they would be restricted to the reversing loop only instead of having to look at 2 sections.
K.D.
Can't post photo because I don't have the rich text option. However My lay out photo IS in the Photo Gallery
This one, right?
You have 2 distinct reversing sections. I see only one "loop," and then there's the wye. I'll have to look at the diagram a bit closer to see if there are actually 2 loops.
In general, you would want an autoreverser for each reversing section. Another issue, though, is that you do NOT want to daisy-chain one autoreverser on to another, because they will end up "fighting" each other to reverse polarity.
Foo. Can anyone see that picture? It showed up when I was writing the post, but not after I posted it. I don't know if it's Windows 7, our paranoid IT department at work or the MR Forum software.
It takes an iron man to play with a toy iron horse.
Here is a link to the OP's track diagram:
http://cs.trains.com/mrr/m/mrr-layouts/2289477.aspx
Let's try this:
Not exactly what I'd hoped for, but maybe it will work.
I've added some red ovals where I think insulators should go. The larger ones cover multiple tracks, and each should be gapped. The circles are single tracks. Both rails of each track should be gapped.
I've set this up with 2 reversing sections. The big one is the whole multi-track arrangement in the lower right. Then, the turntable area wye, including the turtable and roundhouse tracks, is the other section. This arrangement keeps the two autoreversers out of direct contact, so they won't fight each other over polarity.
As I trace the tracks using a 2-color protocol for the rails, I also see two reversing sections, one on the leg of the wye and another on the inner track on the right side of the diagram. The location and number of the gaps that need to be cut will depend upon several factors. And, it is going to require two auto-reversers.
There are three, counting the turntable. You cannot just have the turntable on the tail of the wye and consider it one with the wye - if you spin an engine on the turntable it will be the opposite phase as the wye tail. I'm thinking this MAY work since it will flip the wye tail as you drive off the turntable, and then just flip again if you exit the 'wrong' side of the wye.
As long as the space between the end of the track on the right and the gap on the right side of the wye is longer than your longest engine consist that will run through there, you should be ok. But really only the inner track needs to be gapped, because unless you run in to the inner track, there's no reversing needs to take place.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinkerThere are three, counting the turntable.
That's going to depend on the turntable selected. The venerable Atlas turntable, for example, has built-in split rings and handles any polarity issues automatically, DC or DCC.
So, Mr. OP, what turntable do you plan to use?
rrinker There are three, counting the turntable. You cannot just have the turntable on the tail of the wye and consider it one with the wye - if you spin an engine on the turntable it will be the opposite phase as the wye tail. I'm thinking this MAY work since it will flip the wye tail as you drive off the turntable, and then just flip again if you exit the 'wrong' side of the wye.
Randy, you are correct that the turntable is a third reversing section. But, since the wye should be gapped on both legs and the tail of the wye forms a natural gap at the turntable, there shouldn't be a problem that the auto-reverser can't handle.
One other thought. If the turntable is the Walthers DCC turntable with the split ring set up, won't it reverse polarity on its own?
I really apreciate all the input, My DB150 has the capability of 1 reversing section, my Walthers 130' DCC turntable has its own polarity reverser and the Digitrax PM42 has the capacity for 4 reversing sections. So with that, I should be ok as long as I can get it all hooked up properly. I wish Digitrax had more installation videos available. I find that watching something is more useful than reading about it, especially when the instruction manuals don't provide enough photos.
Dave,
Your DB150 is capable of being an auto-reverser if it is also it's own seperate power district. My DB150 has no 'REV' outputs, but will sense incorrect polarity with another booster and switch polarity.
Now, on to your PM42 - The default 'trip' setting with the PM42 is 3 amps. You can configure each of the four sections as low as 1.5 amps. The sensitivity of the PM42 is not as good as the AR1. At out club we have two PM42 reversing sections, and they work fine with our usual 2-3 HO engine consists. I hope it can 'sense' your N scale engines as they do not draw a lot of current. I have a PM42 with 4 'power districts' and an AR1 for the branch-line and the wye that connects it to the mainline.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Thank you Jim. Do you think you can send some photos or a diagram of how you installed these components? Can you post them or send to my e-mail?
Will multi-function sound decoders draw enough current for the PM42 to sense. My layout is 16'x9' and I haven't divided it into districts, I have less than 150' of total trackage
Aren't these two different things? The trip current for a circuit breaker is the current at which it will shut down the block. For an auto-reverser, the system will sense a dead short and flip the polarity to correct it. It should sense that regardless of how much draw there is from the locomotive. In fact, it should flip polarity even with no locomotives, if you do something as simple as push a metal-wheeled car across the gap with your 0-5-0 hand switcher.
Yes and no. As the wheels JUST begin to make contact across the gaps you have a high resistence 'short' which may or may not exceed the trip current. When they are fully across the gaps - sure, it's a short and will trip. But if it takes a solid short before the reversing is triggered, there will be a hitch or hesitation in the locos and they won't move smoothly across the gap.
Also remember that the PM42 section is EITHEWR reversing or a breaker, not both. So your best bet may be to use a pair of AR1's downstream of the PM42 as the reversers. Or even better, us switch machine contacts (or maybe an extra relay if you need more contacts, and avoid having a short at the gaps in the first place.
I vote for a pair of AR-1s.