Hello...I am admittedly not an experienced railroader, but I recently broke out an engine and power pack from several years ago, bought some new track, and created a quick layout. When I got everything hooked up (DC), the locomotive is either "full on" or "full off"...it won't respond to the speed control wheel on the power pack. The only way to stop it is to turn it off.
I've worked with bad/dirty connections, but don't remember ever troubleshooting a train that won't respond...what could be a culprit for this?
HO scale
MRC 220 Power Pack
Right now just have wires from power pack going to one atlas terminal track.
to the forum. Your initial posts are moderated so your responses and maybe the above post take a while to appear.
There is another similar thread, the MRC is the culprit
http://cs.trains.com/mrr/f/744/t/213998.aspx
Henry
COB Potomac & Northern
Shenandoah Valley
it might be something a simple as wrong connections ... they should go on the left .... the right is for accesories, and doesn't change with the throttle
Put a volt meter across the output terminals of the MRC220 and see if the voltage varies. That's what controls the speed of your train. It might help to put a 12volt bulb on the output. With the throttle turned to min speed the bulb should just glow and turning the throttle should increase the brightness. It sounds like the pot that controls the output has failed.
Alan Jones in Sunny Queensland (Oz)
We have had quite a few inquiries lately about MRC power packs but none re the 220 Tech IV pak (see the thread referenced in one of the responses to your inquiry. I am pretty sure your problem is a shorted output Darlington transistor..probably a TIP 120 or near equivalent. If there's only one output Tx you will have to replace it which is relatively simple to do. If it's two Txs in parallel you probably only have to remove one of the two (unless both failed which is very unlikely). Your biggest problem will be figuring out how to open the case because there are probably security screws which require security removal tools. I don't have a 220 at hand so I can't help you there. The TechIIs all used #10 Torx security screws and a #10 torx security tool is readily available at HF or on the net. The 1370 required a notched flat bladed screwdriver which I made with my dremel cut off wheel. The old 2200 had odd ball screws which fortunately were not recessed so I could get a grab on them with some pliers. Your case probably has two slightly recessed security screws and two deeply recessed security screws.
Your 220 goes for around $70 per so it definitely is worth fixing IMHO. I would be interested to hear what you find out if you do open the case and replace a Tx.
My answer depends on the voltage. My suggestion, simalar to all the others, is to use a multimeter to see if your voltage is varying, because that changes the speed of your locomotive. If your voltage is varying, than check that your power pack is running the correct scale. Most all of my Loco's run on 18.5-17 Volts DC, However, if your power pack is for a smaller scale, It may be putting out a larger amount of volts, thus making your loco run faster than regular operation.
Try the steps listed above. Then tell us how it went.
P.s. In did some research on your MRC 220 Power pack, and somewhere it said it's meant for Z-Scale.
"Your never too tall to play with trains."
~Liam
jer630 Hello...I am admittedly not an experienced railroader, but I recently broke out an engine and power pack from several years ago, bought some new track, and created a quick layout. When I got everything hooked up (DC), the locomotive is either "full on" or "full off"...it won't respond to the speed control wheel on the power pack. The only way to stop it is to turn it off. I've worked with bad/dirty connections, but don't remember ever troubleshooting a train that won't respond...what could be a culprit for this? HO scale MRC 220 Power Pack Right now just have wires from power pack going to one atlas terminal track.
Welcome.
With all the suggestions, you should be able to figure it out. Get back to us when you do. It might help someone in the future.
I tried to answer you last night but the site would not recognize my name and password.
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.
I was going rto suggest the transformer, but here is another issue,
You may not havee connected your track to the track terminals, but rather to the auxiliary terminals.
Most acc outputs are AC in which your DC loco would just sit there and buzz. You might have a accc output in DC, or perhaps you aree running an AC rialroad on the acc cconnections.
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
BroadwayLion Most acc outputs are AC in which your DC loco would just sit there and buzz. You might have a accc output in DC, or perhaps you aree running an AC rialroad on the acc cconnections.
Or you might have connected to the fixed DC instead of the variable DC! This would definitely cause the issue described by the OP! I don’t think fixed DC is ment to be used on locomotives!
I also once had a MRC Tech2 which would not make my engine stop at 0% throttle...
Regards, Isaac
I model my railroad and you model yours! I model my way and you model yours!