[MTH DCS] Voltage Problems

I think you need to get different transformer sooner the better.

Saudi Railways posted:

Lately, I've been having difficulty getting my trains to run at a consistent speed on my small oval layout. I have a DCS TIU and I checked to make sure the wiring was correct (i.e, wires from the transformer attached to the 'accessory' knobs and to the TIU's "fixed voltage" knobs). The problem is most apparent in my PS2 Amtrak Genesis. I'm able to run it fine as an engine alone, but when I add my four Amfleets and dome car to the track, it barely moves and the lighting is extremely dim. I've tested other engines too, like the MTH RailKing Imperial ES44AC, and it seems to be fine alone as well. I don't think it's the battery in the Amtrak, because I got it repaired by a guy in Saginaw, MI (what a commute!).

Here are my specs:

• Lionel CW-80 transformer (I also have the cable for the auxiliary power input and I use that too).
• DCS TIU (very new; bought it a month ago).
• Lionel FasTrack (I cleaned these very recently, so there should be no problems with electrical contact with the pick-up rollers).

 

*Checked the track voltage on the DCS remote, and it said it was 7 or 8 volts. From what I've heard, it's supposed to be a minimum of 10 volts.

*Checked the DCS operating manual and noticed the CW-80 wasn't listed in the table for the compatible transformers.

Am I doing something wrong here? Do I need a different (and more expensive) transformer?

That's a starter set transformer of I think only 80 watts, and you likely need more power. In contrast, an MTH Z 4000 or Lionel ZW supply about 180 watts off of each handle. When running much beyond a simple starter set engine, higher output is needed. For DCS 16-18 volts to the track is recommended. Even with a higher wattage power supply, lights will dim and engines will balk if the track voltage is set too low. You should think about a transformer upgrade, but in the meantime at least raise the track voltage to 16-18 and see if performance improves. But even a single PS 2 or PS3 engine and four passenger cars is pushing the capacity of that transformer. 

RM

Saudi Railways posted:

Lately, I've been having difficulty getting my trains to run at a consistent speed on my small oval layout. I have a DCS TIU and I checked to make sure the wiring was correct (i.e, wires from the transformer attached to the 'accessory' knobs and to the TIU's "fixed voltage" knobs)

...

*Checked the track voltage on the DCS remote, and it said it was 7 or 8 volts. From what I've heard, it's supposed to be a minimum of 10 volts.

...

So to be clear, the TIU Fixed In knobs connect to the CW-80 Accessory knobs as shown here?

Out of curiosity, when the DCS remote indicated 7-8 Volts on track, was this with just the engine on the track or did the reading change when the lighted passenger cars were added?

Yes, the wiring is exactly that.

The DCS remote indicated 7-8 volts when I put the cars on the layout, but when it was the engine alone, it was around 10-18 volts.

Try hooking up the wires to the TRACK posts on the transformer and also hook up to the VARIABLE IN posts on the TIU.  I suspect the TRACK post have more amps and the TIU isn't getting a FIXED input but rather a variable from the transformer.  Crank up the CW-80 and see what it does then.

I would connect from the track side of the transformer to the fixed 1 input of the TIU and keep the throttle on the transformer turned all the way up. I do not believe the accessory side of the transformer is capable of 80 watts.

Saudi Railways posted:

Yes, the wiring is exactly that.

The DCS remote indicated 7-8 volts when I put the cars on the layout, but when it was the engine alone, it was around 10-18 volts.

Is this a typo.  You are reading a rather wide range of 10-18 with just the engine?  Is this with the engine just sitting there?

Anyway.  I knew I had an MTH Amtrak passenger car that I had not converted to LED lighting and made the following measurement.  At 16V it draws a whopping 7 Watts just sitting there.  At 18V the power goes up to 9 Watts. 

Then I measured the TIU power just sitting there with nothing on the track.  It draws a relatively constant 5 Watts of power irrespective of voltage.

I don't have a CW-80 but here's what I found on the Lionel site:

Does the "green light" on your CW-80 flash when the passenger cars dim and the engine is struggling to even move?  I realize you said you cleaned the track/rollers recently.  But if the overload light is not flashing and the CW-80 "thinks" it is doing its job, it could be that something in your wiring/connectors is dropping voltage and thereby starving the engine and cars of voltage.

The implication in the above document is that it is OK to run all power through the Accessory knobs to get the full 5 Amp capability of the CW-80.  And since you are reading (up to) 18V on the track you must have programmed the Accessory knobs to provide more than the factory-set 12V.  But I like Dave's suggestion to simply move the power connection to the Track knobs and the throttle up to full power.

But getting back to the determining power requirements, it is frustrating that manufacturers provide scant information.  Yes, there is wide variation on engine power depending on number of cars pulled, going around curves, up/down grades, etc.  And you do see occasional posts where someone has taken it upon themselves to document some power numbers.

But to the matter at hand.  So with 16V AC on the track, let's say you have 4 passenger cars drawing 7 Watts each plus the TIU drawing 5 Watts.  That's 33 Watts.  Now put on the Genesis; as noted there is no spec but just sitting there with lights on and diesel rev sounds it should draw a bit under 5 Watts.  Add a couple Watts if smoke is on.  Point being you're pulling almost 40 Watts and you haven't even left the station!    And in case it's not obvious, it's the motive power that places the greatest demand on power when running trains.  So if you only have 80 Watts...

I think it is important to swap out the lighting in these MTH cars. On our grandsons layout, we kept burning up stuff. From the track joints, power lock on, to even tripping the transformers included in the sets. They should have switched to LEDs many years ago. It is ridiculous.

 I had kept buying cars without realizing just how power hungry they are. Putting LED strips inside has dropped their power requirements hugely! Someday I'll get them all finished. We have many, very many to do.

My CW-80 and DCS do not get along. I would start by swapping the wires to the "track" posts on the CW-80. When you power up, make sure you do so fairly quickly. I ended up finding a couple MTH Z-1000 transformers, brick only, for a decent price. I now only use the bricks.

The green light does in fact, light up occasionally when I try to run it. I always thought it was because something was off the track, but when I checked, they were on.

About the LED strips; I'm not much of an electrician and I don't want to break something, although they would look rather nice... hmm...

If you make the effort to switch to LEDs each car will draw <1 Watt for the same brightness.  In addition, you reduce flicker from intermittent wheel/roller to track contact, when going over turnouts, etc.. 

If you choose to go with a fixed voltage output "brick" like the 18V AC Z-1000 transformer you may find the 18V AC is too bright when driving the stock incandescent bulbs on your passenger cars.  Hence you'd need to do something about this anyway!

The various comments about CW-80 compatibility with DCS has to do with the type of AC voltage signal the CW-80 generates.  Basically the DCS system works better on a so-called pure-sine voltage as your would get from a fixed voltage "brick."  Obviously it works with the CW-80 since you've been using it!   An analogy might be Premium vs. Regular gas in a car; the manufacturer may recommend Premium but it runs fine on Regular though perhaps with a bit less performance.

I guess you can "do the math" on the cost of a Z-1000 brick (for example) to get a few more Watts of power vs. the cost/effort to reduce the load (LED lighting) on your CW-80.  You can probably sell your CW-80 on OGR Buy/Sell for that matter.

If you choose to work through the Watts numbers, another idea is to buy an AC-adapter wall-wart to power the TIU thru its Aux Pwr input.  This would eliminate the 5 Watts (or so) of power used by the TIU leaving that much more power on the track to drive the engine.  A suitable adapter (you may even have one lying around from an old printer or whatever) runs about $2-3 on eBay shipped or maybe $1 at a local Goodwill store.

Since your green light is indeed flickering, I think the verdict is in that you're over-taxing the CW-80.  So while the head-on solution is to provide more power, it's my opinion that there's something to be learned by working through the numbers on where the power is going and what you might do to manage it...

We were just running last night on the club layout, when we got a couple of passenger trains on one power district, we would occasionally trip the 180W brick.  Needless to say, I put in a pitch for them to upgrade to LED lighting.

It's too bad the market for O-gauge AC trains is small.  For under $10 shipped you can now get a plug-and-play digital meter that measures house AC power.  Seems it wasn't too long ago these widgets were $100 or so.  There have been recurring OGR threads about a meter that displays track Voltage and current/Amps and possibly even power (Watts)...but I haven't seen anything yet!

Those are pretty inexpensive. Wonder if they could be adapted to use with our O gauge power supplies, the PS's outputs that is? I would certainly like to have a meter that gives volts/amps/watts for track power.

Well, it's just my opinion but I see little interest/concern about actual power consumption (Watts) in O-gauge.  The average cost of electricity in the US is 12 cents per kW-Hr.  So a layout max'ing out an 80 Watt (0.08 kW) CW-80 costs about 1 cent per hour to run.  Now if we're talking battery-powered engines where every Watt saved translates to longer run-time then sure.

Anyway, I have one of those $8 AC power meters on the way.  If it looks adaptable to O-gauge, I'll report back but I think the fine-print and oh-by-the-ways will make it more a cocktail-party conversation piece rather than a ready-for-prime-time tool.

I will be watching for your report Stan. If it can be adapted I'm sure you will come up with a way. I don't know enough for that I don't think. It would probably all go up in smoke if I tried it. I think I'm also over due, haven't let the smoke out of anything for a while now.  

The only reason it interests me is for having another gadget to fiddle with. I have an older 120vac volt/amp/watt meter thing like that, I think it's a kill-a-watt or something like that? I get it out and plug something into it every once in a while. I tried it on my train power, but it would be neater on the low voltage side for the trains. I think I will get it out and hook it to the train power again just to see what it reads now that I have more things added.