# Need help understanding MRC Booster use!



## Deane Johnson (Sep 19, 2016)

I started my layout almost two years ago and this past weekend got the double track mainline finished. The layout is about 15 x 25 feet.

I'm powering the entire layout with a MRC Advanced Prodigy Express2. Appears to have about 3.5 amps output.

I've been running a test train round and round looking for bugs in the track work, etc. I'm pulling about 9 Walthers passenger cars with 3 Athearn Genesis SD-24 diesels without incident.

Today, I left an Athearn switcher sitting on another track apparently drawing some power. Now, all of a sudden the MRC Overload light pops on and off. Removing the extra engine from the track returns operation to normal. I guess the current draw must be right at threshold with the extra engine. I'm supposing that means a booster.

MRC has an 8 amp booster available, but I don't completely understand how it's applied. I looked at one document that indicated to me that it's simply a slave that powers a separate section or district of the layout. Not good for me, I don't think, I simply want more current capacity applied to the entire layout.

Can someone enlighten me how I should be thinking in terms of this issue? To me the word "booster" would mean it should go on the output of the basic Prodigy controller to boost the current capacity from 3.5 amps to 8 amps. I'm sensing that isn't the way it works.

Thanks once again for your help.

Deane


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## mopac (Feb 24, 2011)

I would say what you are thinking is correct. You would not use your 3.5 and 8 booster together on same tracks. I over did it with amps. I have an 8 amp system and an 8 amp booster. I was going to have about 80 feet of layout and now plans are about half. What you could do is use your 3.5 in a yard and use the 8 everywhere else. You will have to insulate the 2 sections. What bothers me is 8 amps will weld your wheels to the track on a derail. What I am doing is a power distribution device. Mine has 4 outlets.
You can adjust how many amps it takes to blow with a short. What this will also do is
make it easier to find a short in the various sections of track. All sections are isolated. Hope this helps.


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## Deane Johnson (Sep 19, 2016)

Helps a lot mopac. Not what I wanted to hear. I like the idea of running 4 or 5 engines in a MU configuration.

The damage 8 amps can do with a short during derail is something I actually knew in the back of my mind, but wanted to ignore.

Yuk!

Deane


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## mopac (Feb 24, 2011)

I think one of those power distribution devices will take care of your concerns. 8 amps
will not hurt a thing except in the case of a short. I am thinking you can run your 4 or 5
locos on 8 amps but have a short blow the breaker at say 4 or 5 amps. I don't know what the model number is or even if MRC has the power distribution device. I have digitrax and mine is PM42 but I don't think it would work for you. Mine works on a loconet system. I am not familiar with MRC. Someone here should be able to tell you if MRC has something similar.


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## mopac (Feb 24, 2011)

I got the 8 amp stuff because it was only 20.00 higher cost over 5 amp stuff.
I might be wrong that the PM42 is on loconet. The booster is. A PM 42 might work on a MRC system.


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## Deane Johnson (Sep 19, 2016)

I'm wondering if one could use an 8 amp booster on the layout and just not connect the basic 3.5 amp Prodigy to the rails. I'm thinking maybe the entire layout would be the "isolated section". I don't know enough about the system to know if that would work or not. Seems pretty simple.


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## mopac (Feb 24, 2011)

You have to use your main command station. The command station then runs your booster. It sends commands to the booster. A digitrax PM42 runs in the 40 to 50 dollar range. At least it was 2 years ago. I have one and I am going to pick up another. I am
trying to run 2 different railroads each with double mains. I have that situation here close to my house. The UP and the BNSF each have double mains maybe 200 feet between them. Kinda cool.

You could have your main unit run a siding and then use booster for everything else. But you would have to use both.

Your booster just relays commands but commands need to come from a command station.


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## Deane Johnson (Sep 19, 2016)

My 24 stall roundhouse and 130' Walther's turntable are isolated from the system by nature. I assume I could use the 3.5 amp basic unit to run that complex, and the booster for the rest of the layout?

I'm assuming that if an engine left the turntable with 3.5 amp power driving it, when it moved to a departing rail powered by the 8 amp booster, that the transition would be seamless?

I'm also assuming that all locomotive commands are fed through both power sources by their very nature, again seamlessly?


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## mopac (Feb 24, 2011)

I am going to say yes, seamlessly. The locos only draw the amps they draw no matter
how much is available. I think your roundhouse idea would work.


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## Deane Johnson (Sep 19, 2016)

Thanks for all your help mopac. You've made it all come together for me.

Deane


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## timlange3 (Jan 16, 2013)

As you add more engines (current draw) you need more power (amps). Those with large railroads may have 20 to 50 amps of power available to them. But NOT all at one specific point on the track. They will divide the railroad up into blocks so they have an equal number of engines in each block. Say they have 10 blocks, each block powered by a 3 amp booster. They have 30 amps of power, but not all at the same place on the track. As an engine travels across the railroad it will draw power from booster to booster as it crosses into ajoining blocks. The boosters don't control the trains, they just supply power. Even at 3 amps you want a booster that will turn off power fast in case of a short, at 8 amps it is critical else things start getting welded together!

Booster blocks (sections of track) need to be isolated (insulated) from each other. Insulating one rail is sufficient, but for diagnosing issues, insulating both rails would be better. Best to size the wire coming from the booster based on maximum length it will run and maximum load (amps) it will carry.


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## DonR (Oct 18, 2012)

Deane

There is something wrong if your MRC DCC system
with 3.5 amp output (MRC claims 4) can't keep 2
locos running at speed. My Bachmann
EZ DCC has only 1 amp output yet I regularly run
3 and 4 locos at the same time.

Do you have any accessory connected to your track
or to the output of your system that can be drawing
current? Only if you have stationary decoders for
turnouts should they be powered by the system. Do
you have many lighted cars?

The only reason to need more amps than the standard
for your system is if you run 6 or more locos at the
same time. This would be easy to do if consisting.

If you have a multimeter set it to Amps and connect
the probes where indicated, then connect it between
one wire (either one) and the track. Remove all locos.
If you get a reading there is something shorting or
connected that should not be. If you get no reading
put one loco back on the track. Run it at slow speed.
It should draw around .2 or .3 amps...Note that is
a fraction of an amp. If you have lighted cars remove
them from the layout for this test. If that clears your
short, then one by one put the lighted cars back on
and note the amp draw. Incandescent lights can
soak up current.

Let us know what you find.

Don


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## Deane Johnson (Sep 19, 2016)

No accessories or anything is connected to the DCC. DCC is exclusively track power.

To be clear, I was running 3 engines (SD-24 Athearn) with no issues. It was when I allowed a 4th engine to sit on a track drawing some power while stationary that I got the "overload" flash on the screen. It stayed on a second or so and turned off, doing this cycle every few seconds. Lifting the 4th engine off the track returned things to normal.

I should point out that the passenger cars I was pulling had lighting (Walthers LED), I assume, but they shouldn't draw much current.

Good idea on the current measure, I'll work on it.


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## rickbz28 (Jan 10, 2016)

My temporary layout is run by a Prodigy Advance (original not 2) and I currently have 11 engines on the layout at all times and sometimes more. I have ran 4 in a consist with one having sound. They run without any issues and the whole layout is fed with just one set of very small feeders.


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## DonR (Oct 18, 2012)

Dean a DCC loco sitting idle should draw only
a tiny fraction of amp for the decoder.

LED lighted cars would also be a very minor
current draw. I have 4 lighted passenger and
3 light cabooses that are always 'on' and still
I can run 4 or more locos on my 1 amp controller.

Your 3.5 amp system should have no difficulty
actually running 4 locos. If the 3 locos were running
OK until you put the 4th on the track, there may be
something amiss on that loco. Another member
recently had an unusual shorting problem and
found a loose power pickup wire on a tender touching the track.
You might try running ONLY that 4th loco and see
what happens. Remove the other locos.

Don


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## CTValleyRR (Jul 26, 2014)

So I do have to jump in here. While MoPac's basic advice is correct, there are some details that aren't quite right.

First of all, the MRC Prodigy Express2 is a 1.6amp unit, not 3.5amp.

However, the MRC Prodigy Advance2 is a 3.5amp unit. Which do you have (you said "Prodigy Advance Express2")?

As MoPac says, the command station has to be connected to the tracks somewhere; the booster to a separate block. All boosters work this way. However, since you should have several feeders anyway, this isn't really a big deal -- don't make it harder than it is.

MRC makes both an 8 amp and a 3.5 amp booster. Take your pick, based on the number of locos you intend to run (figure about 0.5amps each w/o sound, more like 1.0 with). You can also get a very nice 5.0 amp booster from Tam Valley Depot (Here: http://www.tamvalleydepot.com/products/dccbooster.html#booster ); the wiring for this unit is on the linked page.

If you prefer the MRC version, here are the wiring instructions for those: https://www.modelrectifier.com/v/vspfiles/resources/dcc/0001505 3.5 amp booster.pdf

Hope that helps.


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## Deane Johnson (Sep 19, 2016)

CT, it's an Advanced2. To make sure I went down to the train room and checked what it said on the top. With my memory these days, I've learned to double check everything. In reviewing my original post, I see I put the "2" in the wrong place after Express, not after Advanced as it should be.

I've already ordered an 8 amp MRC so I'm sort of committed.

I think this is all figured out now, but I'm still going to follow DonR's advice and take some controlled current readings. If something is out of kilter a bit, I want to know what it is. I was too tired tonight to launch into it.

I appreciate your jumping in here CT. It pays to question everything when you're trying to nudge things into place.


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