MRC pure power dual and MTH PS3

I just experienced a very weird problem with my MRC transformer and my Norfolk southern F7 office set. I was able to find the engines on DCS and set up the lash up but was unable to run the units. The trailing unit would not start rolling. It would start up and the sounds would work but the engine refused to move. I was just about ready to send the unit back to MTH for repair and I decided I would check the manual one more time. I noticed that the MRC pure power transformer was no longer listed as a compatible transformer. I dug out my old ZW and connected it up. Well, lo and behold the lash up then worked perfectly!!!!!

What the heck is going on???? The MRC is listed as a pure sine wave transformer and yet my PS3 set did not like it one bit.

Has anyone else experienced this? Obviously there is some sort of trouble as the transformer is no longer listed as compatible by MTH. Any thoughts???

 

Dave

Trains are not a matter of life and death...They are much more important than that!

Original Post

It's been posted here before that some (maybe all?) of the MRC xfmrs are not recommended by MTH. I believe some of the other forum members were a bit stumped by this as well. Not certain the reason was ever posted for sure? If it was I missed it.

Maybe MTH knows something that the rest of the folks here do not know?

I was told that in 2013 at MTH, I was a bit surprised that they targeted now only the electronic throttle model but the Pure Power Dual model as well.  I don't know why, I ran a bunch of MTH DCS engines with the Pure Power Dual and they ran just fine.

gunrunnerjohn posted:

I was told that in 2013 at MTH, I was a bit surprised that they targeted now only the electronic throttle model but the Pure Power Dual model as well.  I don't know why, I ran a bunch of MTH DCS engines with the Pure Power Dual and they ran just fine.

Pure AC is pure AC I find that interesting as well MTH would say that.  Maybe to eliminate any confusion on which is which and which one is safe and which is not

gunrunnerjohn posted:

Hard to say Gary, that could be the issue.  I sure couldn't figure why the Pure Power would have any effect on DCS, it outputs a really nice looking pure sine wave.

I assume this means you looked at it on a scope?  Do you know if the handles are moving a mechanical wiper/tap on the transformer (old-school "pure" sine wave technology) or is it synthesizing the sine wave?  If the latter, it may "look" pure but have some digital artifacts that affects the DCS signaling.   I realize it works for you, but maybe a hi-current 22uH inductor - a couple bucks - would make it more compatible for Dave's particular configuration?

Old school Stan, I took mine apart when I had it.  It had really beefy carbon brushes that ran across a torroid coil, a plain variable voltage transformer.  The only "electronics" in there are the diode boards that get switched in for horn or bell.

So hasn't someone identified a 22uH inductor/choke that would have a good chance of solving the problem?  I'm thinking of the DCS compatibility issues with some early version of the PSX breaker.  It seems the value-added here is to come up with a solution (if any exists) to inter-operating the Pure Power transformer with DCS.

I'm sure you could put a 10A 22uh choke in series with the power feed to deal with the DCS issues, I can't imagine what else might be happening.  Truthfully, since the DCS signal is injected in the TIU on the output side, I don't know how the transformer could really be bothering it all that much.

I like those transformers and am still planning to get one someday. I'll just use it for other things. All my trains already run from PH-180s so they will be fine. I just like the looks of those MRC xfmrs and the gauges, power output, etc.

Curious if the MRC defaults to zero voltage at turn on regardless of non- handle-off position, or does the MRC handle set voltage appear at turn on?  If the voltage is zero then there must be a triac or device to kill voltage until handle set  to off.

Reason I asked is I was considering using a MRC to replace my ZWs, but read or heard that MRC would not power up if handles were not at off (safety feature?)

rrman posted:

Reason I asked is I was considering using a MRC to replace my ZWs, but read or heard that MRC would not power up if handles were not at off (safety feature?)

That's totally incorrect, the handles just set the carbon brush on the transformer coil.  We have one at the club on the workbench, and the handle is always on.  I turn it on to check something, and volts come out.   Like I said before, other than the diodes for the whistle and bell, there are no electronics in the thing.

gunrunnerjohn posted:
rrman posted:

Reason I asked is I was considering using a MRC to replace my ZWs, but read or heard that MRC would not power up if handles were not at off (safety feature?)

That's totally incorrect, the handles just set the carbon brush on the transformer coil.  We have one at the club on the workbench, and the handle is always on.  I turn it on to check something, and volts come out.   Like I said before, other than the diodes for the whistle and bell, there are no electronics in the thing.

Thanks John H and GRJ for correcting my misunderstanding.

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