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Digitrax PM42 Circuit Manager

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  • Member since
    October 2012
  • 53 posts
Posted by The_Ghan on Wednesday, November 7, 2012 5:12 AM

I second the use of the acculites breakout boards for the PM42.  They make life so easy and I wonder why Digitrax doesn't incorporate screw terminals into their boards.

There is two different breakout boards for the BDL168.  If you are using transponding it is often easier to use the multizone version of the board so that only one wire needs to go through each RX.

Cheers

The_Ghan

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Monday, November 5, 2012 5:18 PM

 They are wrong, you are right to be skeptical.

 Study the diagrams in the instruction sheet carefully so you understand the relation of the pins on the edge connector. They ARE labeled - might need a magnifier to see the molded in pin designations, but they do go in order - just don't loose count. As a last resort, you CAN buy replacement edge connectors, they are a standard item and any of the electronic suppliers like All, DigiKey, or Mouser. But the idea is to not mess it up in the first place.

 The connections are arranged in groups of 4. 2 inputs and 2 outputs, and they go Rail A In---Rail A Out---Rail B out---Rail B In. All of the Rail A Ins can connect together and run to your booster, all the rail B ins can connect together and run to the booster. Also don;t foget a wire from the ground to the ground terminal on the booster. And of course the power supply for the PM42, it needs power of about 12V at 300ma, a PS12 or PS14 is suitable, or you cna get something similar from radio shack.

 The rail A and rail B outs for section one go to the bus wire for the first section of your layout, the second set to the bus for the second section, etc. Each section must be isolated from the other - the bus wires cannot connect and both rails need to be gapped at the boundary.

 #16 wire is too heavy to directly attach to the edge connector. #18 is the absolute biggest, and that takes some care. Short lengths of #20 (say 6 inches) to a terminal strip will work fine and not be a problem, you can then attach your #16 bus wires there.

 I used #18, but I've had a lot of soldering experience. My layout bus is #14, so I ran #18 to a terminal strip and then attached the bus wires to the other side:

The 4 position terminal strip on the left is the input, the top 2 terminals are the AC power input, the lower two go to my booster. The bottom strip are the track outputs. The wire is #18 solid, to get it to fit int he holes I actually had to drill them out slightly. The ring terminals I used can handle two #18 wires, although I never trust crimps and actually filled them with solder too.

There is another alternative, the PM42 Breakout Board: http://acculites.com/index.php?main_page=product_info&products_id=574 

Rather expensive at $32 but all you have to do is plug in the PM42 and use the screw terminals to attach your bus lines and the feed from the booster. I suspect the price is high because it is set up to handle a multitude of scenarios, including simple breaker, auto-reverse, and splitting the PM42 between two boosters. However, after wiring two of them by hand (one for my layout, one for the club), I would probably do something similar to this - a right angle connector like that is easy to solder wires to, and the screw terminals are not terribly expensive, and the only other thing would be a small piece of perf board. Soldering the wires to something like that would be easier than directly to the connector supplied by Digitrax.

                   --Randy

 

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    April 2005
  • 2,314 posts
Posted by don7 on Monday, November 5, 2012 4:55 PM

Another question of the PM42.

My layout wiring to the tracks is composed of a 16 gauge bus line with 22 gauge feeder wires to the tracks.

When connecting to the PM42 I assume  I connect the bus line wiring to both of the edge connectors and take off feeder lines as needed to each power district.

I am advised by the hobby shop model train guru that the bus lines connect to the top (only) of the edge connectors and that it is the feeder lines that exit the bottom of the edge connector and attach to each power district.

That makes no sense to me, it is essentially one feeder line to each power district, also the feeder lines which I had always though should be as short as possible will vary greatly in length.

Please advise.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Saturday, November 3, 2012 10:11 PM

 Mine hides up under the layout anyway, so seeign the LEDs isn't important. The nice things is that the PM42 is a Loconet device - so my JMRI panel can display the status of each section, or even sound an alarm if I wanted to.

 You can either mount it so the board hanges down, so you look straight in at the LEDs, or if the board is mounted flat like mine, you can stick a mirror at a 45 degreen angle to reflect the LED out to the edge fo the layout.

 If the holes are still there, you can extend wires and mount LEDs off the board, but any soldring to the board will void the warranty. Likely the SMT LEDs will need to be removed, the chip probbaly can't drive 2 sets of LEDs in parallel. Plus the single red and green ones really aren't important, once the board is configured - and the best way to do that is with the Loconet Checker program, rather than trying to hold the buttons and setting the board address via throttle. The other 4 LEDs indicating the status of each zone are the more interesting ones to watch.

                --Randy

 

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    April 2005
  • 2,314 posts
Posted by don7 on Saturday, November 3, 2012 4:57 PM

I finished wiring up the Digitrax PM42's.

I wish I had the old type with the regular type of LED's.

In order so see the lights you must get within a few inches of the device. It appears I have a slight angle to the board which may be affecting the lights.

I am going to let Digitrax know that I for one, prefer the old style boards with the regular LED's.

I do not think these new miniscule lights are a good business decision. I wonder if one can fit LED's to the board after purchase?

  • Member since
    April 2005
  • 2,314 posts
Posted by don7 on Friday, November 2, 2012 9:23 PM

You are so right, I left a message at the Digitrax site and one of the techs responded. I have a current up to date version, in fact the Digitrax site has not yet updated the pictures of the PM 42 on thieir site.

Honestly, the LED's are super small, almost invisible.

 

 

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Friday, November 2, 2012 7:00 AM

 The likely have switched to surface mount LEDs. They are little clear tabs, VERY tiny. So if there is somethign there and not just two circuit board pads at each LED location, it has surface mount LEDs instead of the wired ones.

         --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    April 2005
  • 2,314 posts
Digitrax PM42 Circuit Manager
Posted by don7 on Friday, November 2, 2012 3:11 AM

I received a PM42 which I am about to install on my layout.

I was just about to install the unit when I noticed that the unit I have does not have the red and green LED lights that are present on the pictures of the Digitrax PM42 at either the Digitrax site or the MB Klien site where I bought the unit.

However, on page 8 of the instructions I  received there is a picture of a PM42  which is exactly like mine and has no red or green LED lights. If you look very carefully at that picture you will see very small tabs where the LED lights should be.

The manual which can be downloaded from the Digitrax site has a different picture of a PM42 than what I received. IT clearly shows red and green LED lights.

Have I a defective unit?

Where the LED;s should be on my unit there are tiny little tabs, almost microsopic they are so small,

Are  the LED's almost microscopic now in size and are on the board and would show only if the board was wired and connected.

I just do not want to change over all the wiring and then find out I have a defective board.that needs to be replaced.

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