# MRC 6200 Problem



## Crete_Street_Riot (Apr 26, 2021)

Hi everyone. I am looking for a little help with the MRC 6200. 

Yesterday I was running the a USA Trains F7 and a LGB Stainz at the same time, but on two different loops. I've done this numerous times without an issue, but yesterday the trains both stopped and the MRC buzzed a few times. I figured I overloaded the system so I unplugged it and let it sit for a few hours. When I plugged it back in, it buzzed once and then did nothing - no power provided to the track and the yellow light wouldn't come on. I unplugged it and let it sit for the night and tried it again this morning. The result was the same.

I saw a previous post with a link to a with repair information. Does anyone have any suggestion about diagnosing the issue? I'm assuming the transistors need to be replaced. I welcome any advice, for when it comes to electricity and electronic repairs, I am in the dark. No pun intended.


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## Greg Elmassian (Jan 3, 2008)

It's not a robust unit... I think there is a single transistor. It really does not have enough voltage or current to be a good choice.

You can fix it, but it will blow again. It has less than 2 amps capacity, and maxes out around 18v.

Look to buying something better.

Greg


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## Dan Pierce (Jan 2, 2008)

Or just run one train at a time on the 6200.


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## Greg Elmassian (Jan 3, 2008)

Even then marginal... under 2 amps, USAT loco can draw over that.


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## toddalin (Jan 4, 2008)

I seem to recall that there are two FETs (or such). I've had one burn out and when it happened, I got full voltage to the rails regardless of the setting. IOW, it had shorted out internally. But it/they certainly could "open" internally just as easily and you get nothing.

I was able to find the replacement which was about $3.50 back at the time and have not had a problem since.

I actually have two of these and on one I converted over to be a more "stable" (dc) supply for the work bench by adding a bridge rectifier and big capacitor. (The MRC puts out very "dirty" power with lots of residual ac and is lousy for building/testing IC circuits.) These can be engaged/disengaged at the flip of a switch on the back.


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## Greg Elmassian (Jan 3, 2008)

If i remember right, I think that one had a center tap transformer... and the 2 output transistors are in parallel, one fails and it usually kills the other... crappy design.

Dave Bodnar has a complete web page on repair:



MRC 6200 Repair



Greg


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## Crete_Street_Riot (Apr 26, 2021)

Greg Elmassian said:


> It's not a robust unit... I think there is a single transistor. It really does not have enough voltage or current to be a good choice.
> 
> You can fix it, but it will blow again. It has less than 2 amps capacity, and maxes out around 18v.
> 
> ...


Thanks for the information. I asked a while back on another post about power supply suggestions. Back to thinking larger. I’m still intimidated by dcc, but know that it will probably make the most sense in the long run.

Currently I have a layout around the holidays for about one month.


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## Dan Pierce (Jan 2, 2008)

When selecting DCC there are a lot of different systems out there. Greg has MCE and Zimo, I have Zimo and older LGB MTS Serial only, and a first generation LLGB parallel system. I repair engines for many people and verify older lgb decoders and others will work properly for these people with the old LGB systems.


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## Greg Elmassian (Jan 3, 2008)

Let me say something about DCC.

It's like a lot of other things in this hobby.

There are people who spend a lot of time putting down things they cannot understand or don't want to understand.

There are people who like to pump up their importance by telling you that it's really difficult (but they are cool because they understand it), or in general warn you about expense (because they like to brag how much they spend).

I make observations on facts, not emotion. There's plenty of REAL data about things in life in general to get good information.

DCC USED to be black magic, fraught with problems, expensive, etc. That is 20 year old information. You can get into it inexpensively, do it bit by bit, and without being a rocket scientist.

There's plenty of people in the hobby that will answer your questions, and help you avoid mistakes.

Greg


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## Crete_Street_Riot (Apr 26, 2021)

Greg Elmassian said:


> Let me say something about DCC.
> 
> It's like a lot of other things in this hobby.
> 
> ...


Thanks Greg. I saw a your replies in a post back a few months about affordable dcc systems. I’ll revisit those.

-Ed


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## Crete_Street_Riot (Apr 26, 2021)

Dan Pierce said:


> When selecting DCC there are a lot of different systems out there. Greg has MCE and Zimo, I have Zimo and older LGB MTS Serial only, and a first generation LLGB parallel system. I repair engines for many people and verify older lgb decoders and others will work properly for these people with the old LGB systems.


Thank you, Dan. I will look into these systems.

-Ed


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## Dan Pierce (Jan 2, 2008)

I made a typo, NCE (not mce) is the one Greg has!!


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## Geared loco (Oct 14, 2016)

Crete_Street_Riot said:


> Hi everyone. I am looking for a little help with the MRC 6200.
> 
> Yesterday I was running the a USA Trains F7 and a LGB Stainz at the same time, but on two different loops. I've done this numerous times without an issue, but yesterday the trains both stopped and the MRC buzzed a few times. I figured I overloaded the system so I unplugged it and let it sit for a few hours. When I plugged it back in, it buzzed once and then did nothing - no power provided to the track and the yellow light wouldn't come on. I unplugged it and let it sit for the night and tried it again this morning. The result was the same.
> 
> I saw a previous post with a link to a with repair information. Does anyone have any suggestion about diagnosing the issue? I'm assuming the transistors need to be replaced. I welcome any advice, for when it comes to electricity and electronic repairs, I am in the dark. No pun intended.


I run both DC and DCC depending on which engines I place on the track. One of my DC controllers is a MRC 6200 which I picked up at a train show for $20.00 It has been a very reliable system I have ran 4 eggliners at the same time for 2 to 3 hours at a time and have never had it shut down. I guess I just got a good one.


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## Greg Elmassian (Jan 3, 2008)

No, the eggliners do not draw current like a USAT diesel... USAT motors have an extremely high stall current, stall occurs at zero rpm also. So a huge momentary current draw that weakens and kills the transistors.

Greg


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## Del Tapparo (Jan 4, 2008)

My club has several of these that have been donated, handed down, etc. They fail on a routine basis. I repair them with the proper transistor and they are good for awhile longer. 
For simple manual control of track power, I offer the "No Frills Track Throttle".


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## Crete_Street_Riot (Apr 26, 2021)

Del Tapparo said:


> My club has several of these that have been donated, handed down, etc. They fail on a routine basis. I repair them with the proper transistor and they are good for awhile longer.
> For simple manual control of track power, I offer the "No Frills Track Throttle".


Hi Del,

Thank you for the advice. So I took the MRC throttle to my dad to learn how to fix it. We ordered transistors to replace, but it turns out a diode was shot and was causing a short.

We ended up ordering the "No Frills Track Throttle" while we waited to get the diodes to work on the other throttle. The "No Frills Track Throttle" showed up today. Wow. This throttle is beast. I'm going to hold off on running two locomotives at one time, but immediately I noticed how strong the lights were running at when minimal power was supplied.

Thank you for this information. This throttle is amazing.

Now on to thinking about DCC...

Best,
Ed


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## Del Tapparo (Jan 4, 2008)

Crete_Street_Riot said:


> Hi Del,
> 
> Thank you for the advice. So I took the MRC throttle to my dad to learn how to fix it. We ordered transistors to replace, but it turns out, a diod had gone bad and was causing a short.
> 
> ...


Glad I could help Ed.


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## Greg Elmassian (Jan 3, 2008)

glad you dumped it, like i said the 6200, crappy design, not powerful enough, not really worth repairing.

Glad you went over to Del, he will take good care of you.

Greg


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## Crete_Street_Riot (Apr 26, 2021)

Del Tapparo said:


> Glad I could help Ed.


Hey Del,

Quick question again about the transformer and USA locomotives. The transformer works great and provides power to keep everything moving just fine.

Something interesting that I noticed today: With the new USA F7 the running lights come on as soon as the transformer is plugged in. However, when I put the GP9 on, the lights don't come on until the transformer is turned to at least 85% power. The GP9 was the only engine on the tracks (no rolling stock either). If the motor was off, the lights still would only come on when 85% power was applied.

I found it odd that one locomotive would run lights when the transformer was simply plugged in and the other didn't light up until power was cranked relatively high.


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## Greg Elmassian (Jan 3, 2008)

So, over the years, the wiring of the USAT diesels has changed.... the original versions are 18v bulbs, track power I believe. Newer versions use a 5 volt regulated supply, or I may have this reversed, it's late and I am not consulting my notes.

In any case, there have been 2 versions on many of the diesels and the main difference is how the lighting is powered.

I can look this up later, but here is an explanation. (Also no one has documented the F7 electronics yet, may be yet another version of electrical design)

Greg


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## Crete_Street_Riot (Apr 26, 2021)

Greg Elmassian said:


> So, over the years, the wiring of the USAT diesels has changed.... the original versions are 18v bulbs, track power I believe. Newer versions use a 5 volt regulated supply, or I may have this reversed, it's late and I am not consulting my notes.
> 
> In any case, there have been 2 versions on many of the diesels and the main difference is how the lighting is powered.
> 
> ...


Thanks Greg.

Another odd component to the situation is that when the MRC was running the locomotives, the GP9's lights would run well from the moment minimal power was applied.


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## Del Tapparo (Jan 4, 2008)

Crete_Street_Riot said:


> Hey Del,
> 
> Quick question again about the transformer and USA locomotives. The transformer works great and provides power to keep everything moving just fine.
> 
> ...


Some loco lighting is sensitive to the PWM output of the No Thrills Track Throttle. You can fix that by adding a PWM to DC Converter.


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## Crete_Street_Riot (Apr 26, 2021)

Del Tapparo said:


> Some loco lighting is sensitive to the PWM output of the No Thrills Track Throttle. You can fix that by adding a PWM to DC Converter.


Thank you Del!


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