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Discussion Starter · #1 ·
PS 2/3 runs in conventional, right? Things have been packed away for awhile and I feel like I've forgotten something. I set up 2 loops and have CW-80s. The MTH, all except the PS/1, power up and make sounds but they don't move. I cycle the power, hit the direction button. NADA. The PS/1 runs fine.

I have a DCS and Cab-2, just don't have them hooked up yet. The Legacy engines run fine in conventional.

Very confused. I swear they would run in conventional before I packed them away.

Frank
 

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Yes, PS2 and PS3 should run in conventional mode. Do you get headlights at all?

Perhaps a conventional reset will solve the issues. If both engines are affected, it may be a power supply issue.

There is also a compatibility issue with the Lionel CW80s and MTH engines. Something to do with the sine wave…

Tom
 

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Oh yes. PS2 and PS3 will run in conventional very well, with their cruise working, too. I have about 50 or 60 MTH locos, a few PS1 (not recommended), many PS2 and gobs of PS3. They run in conventional - all of them - those I bought new (most) have neer run under DCS. Most PS2 andPS3 run well in conventional but a few, including some new ones, jackrabbit a bit and take judicious use of the throttle to control smoothly, but they all work. The headlights work directionally too - at least on all I remember including a brand new PS3 DL109 I unboxed yesterday.

I keep hearing about power supply issues like Krieglok mentioned, but I have never actually had any with PS2 and PS3. ( PS1 yes), Bbut then PS1 was chock full of issues to avoid. I ran a brand new PS3 DL-9 yesterday with a Lionel ZWL. It jackrabbited a bit (nothing I could not handle though) so I tried an old pure sine wave power supply just to see and it seemed actually worse, certainly made no positive difference.
 

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You want to avoid chopped sine wave transformers for MTH engines. You can minimize the jackrabbiting by changing direction with the handle vs the direction button. PS2/3 engines require a higher voltage in conventional. They somehow store energy to maintain speed control. You might note an MTH engine running in conventional requiring 14v and higher current to run the same speed as a purely conventional does at say 8 volts.

Pete
 

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There is a known issue with the PS/3 boards that in conventional mode when power is removed the motors actually go into a braking mode and cause sudden stops, this negates the benefits of having a flywheel. Although nobody at MTH would be specific about the board design, it's surmised that the motor driver circuit imposes a short across the motor when the power is removed by the direction change. This short across the motor causes the motor to stop very quickly instead of coasting on flywheel energy. What Pete suggests is the only known cure, if you slowly stop the engine with the voltage control, you don't see nearly as much of this effect.
 

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Even when I was a kid and just ran conventional I never used the direction button to stop a train, I lowered the voltage with the transformer handle. I knew using the direction button to stop a train, even with postwar stuff, was asking for trouble.
 

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This started out as short post, and I see the notice the forum is giving me that others have posted since I started, but as I got into thist, it seemed worth posting and I had something very relevant to say, even if . . . .

And this probably doesn't matter to ftauss with regard to his original question: Yes you locos will run conventionally . . .

Not to start an argument but I don't see the difference in power supply vs running in conventional and I have looked at that carefullyt. I've tested this (power supply vs running in conventional) in the past and never saw any noticeable difference when running conventional. I think the whole sine-wave vs chopped power probably does matter, a lot, when you are running DCS (my EE background tells me it almost surely must) or TMCC Legacy (it tells me it is less likely but probably). But conventional? Never seen it in a lot of looking.

I have multiple power supplies that I can switch onto to my mainline 1 whenever needed. I normally keep a ZWL connected, and run anything and everything with it, but I have that ZWL onthe layout operating shelf, and sitting on a bench to the left side lined up for alternative use:
Lionel ZW40 and ZW80
MTH 40-750 75 watt O-Gauge power supply
Marx - old, from the 1950s, but rebuilt. Generates a near perfect sine wave
Lifelike 0-16 volt DC 6W power supply (good for testing LEDs, and not much more)
Three lab bench grade power supplies;
  • DC 0-50 volt power supply - old but looks just like those sold now by AIWA. Not relevant here
  • Eisco AC since-wave 0-12 VAC 6 W power supply. Can;t make the voltages or current levels needed to test O-Gauge.
  • Yonntech 0-130 V 20amp 2000W regulated autotransformer. An awesome v ariable AC power supply.

Conicidently, I played with with this (the power supply issue and jackrabbiting) yesterday with MTH's new DL-109/110 set. I was preparing a discussion and photos of it for next Tueseay, and had just taken it out of the box.
Below: photo of my PS3 Premier PS3 DL-109/110: a big, shiny, ugly, and somewhat flawed model locomotive A-B set. I will post more details about it next Tuesday.
Slide1 - Copy.JPG


Anyway, the poweedr DL-109 unit above surprised me by jackrabbiting a lot in conventional when starting, when powered by my Lionel ZWL, more than any other new loco in years. And it jerked to a halt even worse when brought to a stop - really badly.
You guys are right that to minimize that you have to avoid using the direction switch and operate the throttle slowly and smoothly, but while that made matters tolerable, it did not cure jackrabbiting/jerk stops completely with the ZWL.
I switched on a MTH 40-750 power supply and it made no difference. No difference I could tell. I emphasize "I could tell here" because I have no way to measure jackrabbiting and so can't say for sure it was better or worse. But it did not seem so . . .

An old Marx unit ran it well, but just the same. It is an ancient but rebuilt unit and about as traditional a sine-wave generating power supply and you get.
Finally, I tried the Yonntech - it is a big, very powerful unit that is loafing - not near hysterisis or any other built-in limit of its design - at voltages and current outputs that a single O-Gauge loco will use. It is an autotransformer and they are known for making almost-but-not-quite-pure sine waves, but any difference is going to be very small and insignifcant here - in the past I looked at its output with bench equiment (scope, simplistic spectrum analyzer), and it rated 99% pure at anything under 20 V and 5 amps.
Jackrabbiting was no better or worse that I could than with the Lionel.

The power supply did not matter, but the handle did. No matter what power supply I used: Lionel, MTH, Marx, or Yonntech, the PS3 DL-109 seemed to jackrabbit to what seemed to me the same extent But the Lionel throttles - vertical levers with a lot of room for movement made it much easier to use to operate a start-stop smoothly than the MTH or Yonntech, which have a round twist knob, or the old marx, which has a twist lever. I wish I had my old Z4000 from MTh to use to test these locos, but I don't. I'm pretty sure though, that it would not matter at all.
 

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Yep, I didn't address the jackrabbit starts as I don't know how to totally cure those either. :D I know that I can run a PS/2 and PS/3 locomotive here and the behavior when you suddenly cut track power is vastly different, the PS/2 is much more graceful stopping and the PS/3 just skids to a stop.

I'd be curious what results you'd get starting at an even lower voltage with a couple of diode pairs in series with the track feed to lower the starting voltage.
 

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Thanks, I did not know about the track power. The two diodes in series are something I will try if I can find some in the workshop i will try it. Very intersting that it is worse on PS3 than PS2, and on the4 DL rather4 than some of the other recent Premier locos. The first time I stopped the DL, wham, it stopped !! Tthe lead unit jerked to a halt a de-railed its rear trucks and three of the eight car train jumped a truck off the track, too.

It is too much like the work I used to do, (yuuck), but I am thinking about a small assembly with a super-capacitor and an oscillating circuit that, upon power shut off, would feed the super-cap's stored power into the loco. When I used to put super-caps into Superstreets cars so they would ignor minor electrical connection problems endemic to those tiny things, they would always run on for five to forty feet after power shut off with the power from just a super-cap stack about the size of six quarters. That and a tuned circuit to let ir release power only at something around 60 cycles would probably make the motor turn for another second or two, easing the jerk at stop, which is terrible on the DL.
I know the idea could be made to work, but it would take some work to size and test it and I'm just not liking that too much any more. It would be a viable thing to build and manufacture but not a good product: your market would be hobbiests who run conventional - not the type who are going to be into ioopening up their loco and installing a new board.
 

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Discussion Starter · #11 ·
Um, fellas, the question was "should PS 2/3 engines run on a CW-80?". If not, why not? If it is the chopped wave? All steamers except the PS 1 light up make noise but don't move. Cycling the throttle, direction button, it doesn't matter. I also have 2 diesels, I tried one and it had the same issue. I have another that I KNOW FOR SURE I ran with the CW-80 maybe 6 years ago as I had neither Cab-2 or DCS at that time. But I haven't that one yet.
 

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Um, fellas, the question was "should PS 2/3 engines run on a CW-80?". If not, why not? If it is the chopped wave? All steamers except the PS 1 light up make noise but don't move. Cycling the throttle, direction button, it doesn't matter. I also have 2 diesels, I tried one and it had the same issue. I have another that I KNOW FOR SURE I ran with the CW-80 maybe 6 years ago as I had neither Cab-2 or DCS at that time. But I haven't that one yet.
I think this may answer why the CW-80 is a problem on many PS/1 and PS/2 locomotives. Check the ringing on the waveform!

CW-80 Transformer Waveform at Half Throttle and Full Throttle
560845
560846
 

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Well, the ringing may cause problems with DCS operation but I have a CW80 I used to power my #3 mainline and I run MTH a lot up there in conventional, including a couple of little Premier steamers (the PRR 2-8-0, a 4-4-0) that run sooo sweetly on it. I think both are PS3 but not recent PS3 - they are both a few years old - and both do well with the CW80.
 

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My experience over the years with Lionel's 80 watt transformer is that they do not go completely to zero voltage when the throttle is closed or with the reverse button. There seems to be a residual voltage and MTH units require voltage to go down to zero for electronics to cycle.

I tried on several transformers just unplugging and quickly plugging back in and the MTH engine would then cycle.

Good luck with your issue,

Don
 

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Um, fellas, the question was "should PS 2/3 engines run on a CW-80?". If not, why not? If it is the chopped wave? All steamers except the PS 1 light up make noise but don't move. Cycling the throttle, direction button, it doesn't matter. I also have 2 diesels, I tried one and it had the same issue. I have another that I KNOW FOR SURE I ran with the CW-80 maybe 6 years ago as I had neither Cab-2 or DCS at that time. But I haven't that one yet.
Perhaps a stuck button on the transformer? Bell, Whistle or direction? Just spit ballin’ here after reading about possible causes….

Tom
 

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I think this may answer why the CW-80 is a problem on many PS/1 and PS/2 locomotives. Check the ringing on the waveform!

CW-80 Transformer Waveform at Half Throttle and Full Throttle
View attachment 560845 View attachment 560846
IIRC, some of your custom electronics have an inductor to limit interference with the DCS signal. Could a similar approach work for chopped wave transformers?
 

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IIRC, some of your custom electronics have an inductor to limit interference with the DCS signal. Could a similar approach work for chopped wave transformers?
Different animal. DCS is a high frequency signal riding within the track power. The inductor is a choke and blocks the high frequency DCS signal from being shorted out by the load. In other words, an inductor in series has low resistance at low frequency (60Hz AC) but has a much higher resistance at higher frequency. Again, the idea is the inductor chokes off the DCS signal with high impedance (complex resistance) so as to present no effective load to the DCS transmitter so the rest of the track and engines sensing the signal get full strength. Again, the problem is, many loads also load the DCS signal, thus making anything else trying to receive the signal see less signal. The inductor is there to block the signal in a way from being shorted out by the load.

My honest opinion is that there are multiple problems with the CW 80 output and no a single passive device is not likely to correct the waveform. The first thing, look at the fast rise on turn on for each positive and negative swing. No slope at all just a massive instant rise. No curve of the sine wave.
560941

I think the swinging or ringing is capacitance in the output, and that's why after a slamming instant on rise, we see the output do that intense ringing until it decays on the downward slope of the sine wave. FWIW, that kind of swing is extremely destructive in DC circuits and why it's not a good idea to put a mechanical switch into a DC circuit. https://www.pololu.com/docs/0J16/all
560939


It would be fun to see a real world test, but again, gut instinct and 3 years of night school says nope, that (an inductor in series) is not the answer.
Some Google searching showing what an inductor in series with a square wave source becomes like a shark fin.
Better example updated. Electric Circuits Fundamentals - ppt download
Vs is the voltage source. Basically this is your CW80 output AC variable that has a rising edge square wave shape.
VL is the voltage across the inductor.
Vr is the voltage across the resistive load- basically what waveform your train would see.
Even more
spike like than the original.
560946
 

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Try a different transformer, if you have access to one…

Tom
 

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IIRC, some of your custom electronics have an inductor to limit interference with the DCS signal. Could a similar approach work for chopped wave transformers?
Something might make a difference, but given those spikes have significant energy, it would be an expensive solution. I just avoid the CW-80 like the plague, solves the problem for me.

My DCS and TMCC/Legacy all have pure sine waves to sip on. :p:p

560963
 

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Okay, check the tether connections to see if they are tight. Do a reset on the loco. I have a finicky PS-2 steamer that needs to be reset every once in a while. Simple process. Read the manual. With the loco powered up, press the whistle button, turn off the power, and then release the whistle button. You should hear a clank after three seconds. Apply power again and the engine has been reset. If the battery is good it should then run normally. Perhaps it's a battery problem. Replace with a BCR.
 
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