Z-Scale Max Voltage

What is the max voltage that a person should use for a Z-scale MTL GP35 loco? I think I read 8 volts one place and 10 volts in another place. Also, I have noticed that a person can buy a modified MRC 1300 Power Pack, but the description just says that it is externally modified; I am assuming that it is some sort of throttle stop. I have several powerpacks from my N scale and thought I could probably just put a throttle stop on it. Any thoughts?

 

About 9 volts. But nothing is going to blow up or burn up if you just run it normally. The problems come when you overload it. That means, make it work hard or, stall it. So 10-20 cars or slight 2%-like grades are fine. 50 car trains or steep 4%-like grades means loading. So you see it run "slower" so you turn up the power pack a bit more to compensate. Thats were the trouble comes from.

What power pack do you now have ? You can use most any N power pack, if you don't turn it up to "10" (by that I mean full). You dont need the specially modified one if you know how to not turn it up past "8" out of a "10" scale.
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Be careful with some powerpacks. If the maximum voltage output is 16V, but it generates constant 16V pulses, the throttle stop makes no difference, the 8-10V rated motor gets 16V pulses. It's the dead sentence for your Z-scale locomotive. There are pulse generating circuits with Z friendly waves, make sure you use the correct one.

 

Good morning and thanks for the replies. I am not an electrician, but would the 16V pulses show up on a meter (I have a Fluke meter)? Also, would the MRC Tech 4 or the Kato N-Scale powerpacks have these pulses? I alos have an older MRC 2400 that has a switch to turn on or off the pulse; would that one work? Any recommendations would be great. Thanks.

 

Most normal test meters will show pulse power on the AC setting but for Z we want DC voltage and testing with a multi meter is not going to guarantee you have DC. Many of the power packs around today are not pure DC they all have some AC ripple so the only pure DC is from a battery. So for Z you want a power pack that was designed for Z and it could have pulse. But the generic MRC throttles are not designed for Z but for HO and N and so are too robust for Z. The MRC throttle from Micro Trains is okay for Z but Ztrack has other options which I think are better. You can use other throttles if you know they are DC and keep the track voltage to less than 9vdc. typically on DC most engines will run fine on as little as 3vdc and average around 4 to 5 vdc when running on your layout. Most engines will leave the track if run at 9vdc. Your Kato power pack could be fine but it depends on the model. With any power pack if you leave a train running and are not watching it could short out on a switch not set properly and you end up burning the motor due to excess amperage for too long a time period. Power Packs designed for Z have a voltage and amperage limits which are Z friendly but are not operator proof. There are many of us who have used or still use other power packs but we know our equipment and how to operate it in a Z friendly manner. In my book MRC pulse power packs are not Z friendly.

cheerz Garth

 

Read Jeff's previous post on this topic because he hit the head of the nail. These voltage limits are what the motor will withstand sitting by itself on a test bench and not installed in an engine. No matter what power pack you use if you overload the model engines motor even with a power pack designed for Z you can burn the motor out. You can use any DC power source provided you have a means to monitor the voltage and amperage. too much of either will burn any motor be it N scale or Z scale. The biggest problem with N or HO power packs is the maximum amperage they can deliver in a short circuit condition before the circuit breaker pops or the fuse blows in the mean time the motor in your GP35 is toast. A typical GP35 will start to move with as little as 2.5 volts DC or less and run with 20 to 30 cars at about 100 to 200 millamps or less depending on the slope of the track and the number of cars it is pulling and the condition of the wheels and track. Putting two geeps in series the starting voltage stays almost the same but the running amperage will be double. that of the single engine. so I say for most Z layouts you need a power source which has a variable output of 0 to 8vdc or it could be as high as 10vdc and the current limit is limited to 500 milliamps. This is enough power to run a triple headed train with GP35's or double headed train with a pair of F7's without risking damage to your equipment all things being equal. Every engine engine has a signature voltage it will start moving at and a an operating current running light or loaded. When new they will be slightly higher than when they are broken in. I can't speak for others but I record those numbers and monitor them on my layout as I have voltage and current meters that tell me these numbers while the train is running. Not everyone does this, probably only a few of us who actually do this or know these numbers for our engines.

 

One trick than can be used to prevent overvoltage, is to use diodes is series with one wire to drop the voltage. A standard 1N4001 diode drops around 0,7Volt for each diode. If you use the diodes before the direction switch, you use a single line of diodes, connected in serie. If you put it after the direction switch, use 2 diodes connected anode to cathode and cathode to anode(in paralell) and use as many diodes in series you need to drop the voltage. If your powerpack gives 14 Volt and you want to limit it to 9 volt, you can use 7 or 14 diodes(7 x 0.7Volt= 4.9V drop) in serie on one of the powerwires.
I have done this for 25 years and it works great.

 

Lajos and Garth are correct in their warnings about 'Pulse power' packs. They should be avoided (ONLY due to the high "16" volt pulse). As for the higher current issue, it is more of a problem for stalled motors. The weaker, low power packs, like the Märklin or MRC's lowest model (1300?) are not regulated and under increasing loads, the voltage will somewhat drop as the current increases. However, they too can still deliver enough damaging current to a stalled, bad running loco if you try and force up to 6, 7, 8, 9 or whatever volts.

A loco under load (long train, grades, tight fitting/misaligned chassis or, dried up lube) will make your loco run slow. Then, even at "9" volts, if the power pack is weak it will still deliver it's best current. Even the weakest power pack can potentially damage or at least overheat a loco to the point where the shell may melt.

All I can say is that it is not really an issue if you just pay attention. There are 100,000's of thousands of these Z scale locos running out there, many in long day operations without issues. Also consider the 1000's of us running DCC. The typical DCC set puts out 12 volts or higher, with up to 50 or more volts of very short transients (mega shorter than the "pulse power" packs). Also, 1000's of Z scalers use the Relco, Miniatronics, etc. electronic track cleaners. When the loco is making proper connections to the track, the circuit does not function. As soon as there is discontinuity, the electronics kick in 100's of volts (of extremely low current, like electrostatic) to force the assumed crud to be blown away, helping re-establish electrical contact. Once everything is reconnected, the electronics immediately removes the 100's of volts. However, during that instant reconnection, the motor sees that for an extremenly short time (microseconds). Again, 1000's of people using these for hours a day, day after day, for many years.

Bottom line: run your trains ! Enjoy the time watching them run. But, always watch your trains ! A stalled loco is always a problem, no matted how it is powered.
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Correct, it's a safe way to protect the motors rated 8-10V DC. The problem is, the diodes in line eliminates the effectivness of pulses, so the low speed performance of locomotives will be substantially poorer.

 

Hi Dave, if you get a battery controller you won't have to worry at all. Z track sells them. Also, some come with a plug in device. If you are just getting into Z, the battery controllers are portable and easy to switch.

The locos will run well on power packs without pulse, but I think that has been covered.

 

So, with the info given by many of the experts here, does anyone have a specific controller/power pack that they prefer over others? Being new to Z, I was about ready to pull the trigger on the MRC Railpower 1300, the one that MT slaps their label on for Z-specific. Seemed like a logical choice to run my MT F7's and GP9's on.

But, it sounds as though some of you "may not" recommend this unit. Is there something better I should persue? Keep in mind, I'm aways out from DCC yet, but could graduate into it.

Lance Mesa, AZ

 

Robert, Thanks for the welcome and quick response -- this is the reason I come to this board is the wealth of knowledge and respect that the members offer! Now, being a newby in Z-scale, I am still trying to wrap my brain around the nuances of what is good and what is bad.

I am running (well as soon as I get power-LOL) all Micro Train engines -- F7's and GP9's. That may not matter, but I have a pretty good understanding of the ole' F7 issues, and hear the GP9's are stellar.

With that said, sounds as though it comes down to the modestly priced MRC 1300, or the more expensive Marklin white unit, assuming that it is compatible with the Micro Trains engines.

I'd rather get the right unit the first time. Which would be the best bang for the buck?

Thanks in advance for your time.

Lance in Mesa, AZ

 

Hey Lance,

Another hearty welcome to the forum. I want to chime in with another possibility. Last weekend I had the opportunity to try out Rokuhan's new controller. The dial is *VERY* smooth, there is a much nicer directional switch, and there is fault-protection built in. Also, if you ever use Rokuhan's turnouts, the capability to control two of them is built-in to the power pack. I ran AZL and MT locos on it no problem, and I have to say that it blows the ubiquitous Marklin white brick out of the water.

That being said, they appear to be rather hard to acquire right now. Perhaps you can get by with the MRC1300, and then 'upgrade' later?

Good luck!

-Zcoast

 

I agree with Lajos if, you are new to Z I suggest you visit or go to Ztrack Center: Assorted Electronics web site and look at the power packs available there. No I have no interest in this business but I know the equipment sold there has a good reputation for controlling Z trains. I have used some of them my self. I also use Japanese Z gauge power supplies from RealZJ (green) and the newer version from Crown (Black) that go with their modular road bed track systems and are essentially plug and play. There is a new player on the block Rokuhan and their new controller is also a very good device and it should be available from a North American distributor by early summer. The Rokuhan and Crown units are available from Japan currently and have a wall transformer or optional battery power in the case of the Rokuhan one in a self contained unitand it is also a plug and play unit designed to go with their road bed track system. I use a combination of 6 of these units to run my show layout which is 2x4 feet and has 5 loops of track so I can run 5 trains at once.

 

Wow -- some great info from everyone. Plus the ZTrack Center was a great recommend. Been on the site a couple of times, but overlooked the Electronics sections as I have not been ready to pull the trigger on a power source --- but here we are today, broaching the subject.

Well, I may just take Zcoast's recommendation and grab an MRC 1300 ($40.95 at ZscaleMonster) and make due, until the Rokuhans become available. Sounds as though most of you have a variety of power sources, so I don't want to be an outcast with just one --- LOL.

 

I prefer the Low Speed Controller FR-1. It has a knob to preset the acceleration and braking and it also has a button for "Switching mode". I recommend it.

http://www.passmann.com/_fr-1e.html

 

Thanks for all of the input, but I am still wondering what modifications have been made to the MRC 1300? I mean really, this is about the cheapest power supply (without mods) that can be purchased and even with the mods, it is only a few dollars more. I would think that a Tech 4 would be a much higher grade power supply than a 1300. Again, thanks for all of the input.

 

A simple stop installed at the knob to limit the voltage output. The MRC1300 is proven safe for Z-scale locomotives, it's reliable and economical. When you're not looking for mobility, it's a good choice, go for it.