Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

How do you test a power pack?

1897 views
9 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    December 2014
  • 443 posts
How do you test a power pack?
Posted by Wolf359 on Tuesday, October 23, 2018 4:50 PM

A neighbor who knows I'm a model railroader recently gave me a box of accessories, a Varney F3 locomotive, (which I got working) and an MRC power pack. My question is how can I tell/test if the power pack is safe without possibly frying anything, or myself? It's an MRC TRAIN PACK, model T2B with an input of 115V 60 AC, and output of 15V DC 1000MA 10W 17V AC. The cord looks like it's in good condition with no cracks, but beyond that I don't know if the unit is good. Also, does anyone have an idea as to the age of this unit?

Thank you.

  • Member since
    June 2007
  • 8,892 posts
Posted by riogrande5761 on Tuesday, October 23, 2018 4:57 PM

Wolf359

A neighbor who knows I'm a model railroader recently gave me a box of accessories, a Varney F3 locomotive, (which I got working) and an MRC power pack. My question is how can I tell/test if the power pack is safe without possibly frying anything, or myself? It's an MRC TRAIN PACK, model T2B with an input of 115V 60 AC, and output of 15V DC 1000MA 10W 17V AC. The cord looks like it's in good condition with no cracks, but beyond that I don't know if the unit is good. Also, does anyone have an idea as to the age of this unit?

Thank you.

Do you have a VOM meter?  You could hook up the leads to it and run the potentiometer up to max and back down and see if the voltage runs up to something in the neighborhood of 12 to 16 volts and back.  If the meter goes the other way switch the polarity (direction) on the power pack.

Rio Grande.  The Action Road  - Focus 1977-1983

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 9,094 posts
Posted by BigDaddy on Tuesday, October 23, 2018 5:17 PM

Maybe Randy can say definitively, but putting out too much power seems like an unlikely mode of failure to me.  Whenever the question comes up of how much power do I have, a voltmeter is almost a necessity.  A Harbor Freight $5 voltmeter is good enough.

The T2B on Ebay, for $13  BIN, has a bronzeish case and the address is Brooklyn 34, NY   Zipcodes started in 1963.    Howard Zane uses MRC transformers to run his turntables.  While I didn't see a T2B, it's a potentiometer and old doesn't mean much.  Someone told me that when the reactivated the USS Missouri for Vietnam, they still had tube system electronics and FDR stationary in the admirals cabin.

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Tuesday, October 23, 2018 6:11 PM

The specs I found on the TB-2 says it has a Rheostat, if so You will have to test the voltage under load to see if the rheostat works.  Use an automotive bulb as a load and check to see if you can vary the brightness of the bulb with the throttle.  Try it in both forward and reverse.
 
Mel
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Tuesday, October 23, 2018 6:56 PM

First I would make sure the 120 volt AC cord has no cracks in the insulation.

I the pack has a metal case and quite old I would check on the AC scale with the meter between the metal case and the outlet screw on the wall for AC leakage in case the insulation on the transfomer inside is old. Happened to me many years ago. I put a three wire cord for grounding the pack on it. A GFI prptected outlet might show it.

Connect an auto light bulb for a load to the output. Use a multimeter to measure the voltage and current.

Meters I have used for some years.

http://www.trainelectronics.com/Meter_Workshop/index.htm

http://www.trainelectronics.com/Meter_HF/index.htm

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Tuesday, October 23, 2018 8:27 PM

 While that old power pack may be fine and actually work, it won;t be able to control most newer trains, because of the rheostat. That old varney loco would run fine on it, but newer locos draw a lot less power, which combined witht he rheostat coontrol mean they will tend to take off at full spped when yoou just barely crack the throttle.

 If it works (and yes - there's is practically no chance it can put out too much voltage. Worst case would the the rheostat is shorted and it put out the full 12V or so all the time) it might be useful to power accessories or something.

                                     --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
    January 2006
  • From: Northeast OH
  • 2,268 posts
Posted by NeO6874 on Wednesday, October 24, 2018 4:49 AM

1 amp output will drive a few hundred LEDs at full power (and even more if you cut them back to 5-10 mA).

-Dan

Builder of Bowser steam! Railimages Site

  • Member since
    December 2014
  • 443 posts
Posted by Wolf359 on Wednesday, October 24, 2018 2:11 PM

Thank you everyone. The information you've given me will be very helpful.

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 18,255 posts
Posted by SeeYou190 on Saturday, November 17, 2018 7:26 PM

RR_Mel
Use an automotive bulb as a load and check to see if you can vary the brightness of the bulb with the throttle.

.

This is the easiest and safest way I know of to test a throttle pack. I combine the buld with a voltmeter. This is a dynamic test that tells you a lot more than simply using a voltmeter.

.

An 1157 bulb with both filaments in parallel is my choice for a good load.

.

-Kevin

.

Living the dream.

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Saturday, November 17, 2018 7:48 PM

SeeYou190

 

 
RR_Mel
Use an automotive bulb as a load and check to see if you can vary the brightness of the bulb with the throttle.

 

.

This is the easiest and safest way I know of to test a throttle pack. I combine the buld with a voltmeter. This is a dynamic test that tells you a lot more than simply using a voltmeter.

.

An 1157 bulb with both filaments in parallel is my choice for a good load.

.

-Kevin

.

 

Like Kevin said, get the 1157 bulb. Go to auto store. Get the socket also. Tie both wires together. Use the link I posted earlier for two meters. Curent and voltage.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!