New Kato Mikado 3rd run engine

[cjp53]

First all thanks to everyone,I have learned a lot.I have been out of the Hobby since the 90's and things have changed.I looking for a different power pack regardless where the problem lies.When I started my layout in the fall I had one line in and purchased a used 1300 pack.Since then I add another separate line so I'll need ether a duel which I think I'll get instead of another single.A friend's brother I went to school with many years ago has a train shop.That's were I got the 1300.I reached out to him last night to see what he has on hand at the shop and still waiting to hear back.When it comes to electronics I'm lost so this was good to know about possible problems with the 1300 & 1370.The engine is on it's way back to Mike,I too will be interested to see what he finds.

[mike_lawyer]

I busted out laughing.
I thought it was funny and appropriate.

I know I can't wait to find out what Mike discovers.

And CJP53.... please don't be embarrassed.   You obviously noted something was amiss- and we agree with you.  Something's going on.
Railwire should be a great place to ask questions and explore things.

That's what is great about this board ... We all help each other out to solve problems.  The amount of collective knowledge on this board is amazing, I have learned so much over the years.

I will do a dissection on the loco and post what I find.  I suspect that a prior owner may have installed a decoder in the loco, but I never knew it.

[randgust]

I've evolved into an unnecessarily complicated power array between my layouts and modules - but it makes for a GREAT testing lab....

Original ATSF layout started out with an HO MRC Golden Dual Loco pack from the 70's that's still working as a 'static' power supply.  It has additional banks of resistors to bring it down under control, with on-off toggles to select the range.  But now it's only used to supply power to two transistor throttles, a rebuilt CAMA throttle (remember those?) and a pair of PSI 550 cabtrollers with momentum and braking.   The accidental discovery that lowering the input voltage got rid of the noise, heat and chatter of all these has allowed this to remain primary power and I'm still very happy with it.  They REALLY work well, but unless I'm testing an analog DCC receiver, I never hit the toggles to set the power back to straight DC.   But with up to four locomotives on a  heavy train, adjusting the power output to the train size is very much needed.   I'll run about 40% power with a yard switcher and 80% on 4 Kato F7's.

The Hickory Valley and Ross Run modules has always been an MRC 501N with additional rheostat on the output voltage to REALLY knock it down.  I find that the pure, highly restricted DC works well with the tiny Kato pager motors in my logging locomotives that are so tiny that DCC really isn't an option, let alone that there's no way to run multiple locomotives on modules this small.

All my five T-trak modules are designed as "dual fuel" so that I can plug in a Digitrax Zephr to test them under DCC as they are usually run that way at a show, or toggle them over to DC if I plug them in to home layout.  I've cut my chops on DCC that way, with mixed results.   I can run any DCC receiver and test it this way.   Some of my custom builds are DCC, so I've had to learn it.

And finally, my foray into Nn3 proved that NOTHING I had could control those tiny pager motors down to creeping, even with a gearhead - until I got one of the Snail Speed controllers that runs with an internal 9V battery.   Wow, that's a cool throttle.   I've adapted it to work everywhere my other throttles do as a plug-in unit.

So by my count, I've got five different power supply systems going.   So my anecdotal evidence on about every possible glitch is based on finding new ways to do almost everything wrong and observing magic smoke at times.   Careful planning is no substitute for accidental analysis!   Which led to the revelation that DCC decoders HATED anything that came off those DC transistor throttles no matter what I did to lower the peak voltage.   The random reversing and no reversing at all was interesting, and just sitting there humming and laughing at me with both headlights on (Atlas GP) was similarly amusing.

[mmagliaro]

FYI, the rated maximum output of the Tech 7 760 is 23 VDC. Same for the Tech 4 220 and 260.
http://www.modelrectifier.com/v/vspfiles/resources/dc-ac/TECH7_Manual.pdf
https://www.modelrectifier.com/v/vspfiles/resources/dc-ac/Tech%204%20200-220-260%20AB111_121_131.pdf

Tech 7 760:

On the 1300 paperwork, it says the maximum is 15 VDC, which we know from the O-scope, has to be the RMS value, not the peak.  I wonder why would two models of the Tech 7, the 700 and 780, be rated at 14.5VDC, while the 760 says 23 VDC?   In any event, yes, I think all of them are higher than I realized.  None quite hit the 25v mark that the 1300 does, but 23?  Why oh why?

I like Tony's (Skipgear) suggestion about that MRC diode limiter.   It's just a bunch of heavy diodes in series, but it's a neat drop-in product and it will do the job.

FYI... this is one of the reasons I gave up buying commercial power packs 40 years ago.  A home-made "transistor throttle" is pretty easy and cheap to build, and that way, you KNOW what it's doing instead of guessing.
 

[cjp53]

MRC used to sell a voltage limiter diode array to bring the voltage down for N and Z scale. Look up MRC AT880. I have one in my stash someplace but seeing as everything I have will be DCC eventually, I haven't looked for it in a long time.

edit...found it.

https://www.modelrectifier.com/product-p/at880.htm

I have zero knowledge with electronics,how would I use this with my 1300?If I add a 1370 which a local train shop is holding for me(they are closed by the virus)would I have to add another?And exactly how do you install it?

[cjp53]

I have zero knowledge with electronics,how would I use this with my 1300?If I add a 1370 which a local train shop is holding for me(they are closed by the virus)would I have to add another?And exactly how do you install it?I have two separate tracks and need another power pack.

[mmagliaro]

You just wire that MRC voltage dropper device in-line in one of the leads that go from the power pack to your track.  It will have instructions with it.
If you have two power packs, yes, you would need one device for each one.


Like so:
(I realized after I drew this that I only showed 4 diodes in each direction... but that is not relevant to how
you hook it up)

[randgust]

The reason this works is that each individual silicon diode drops the voltage - not the current (like a resistor) .6- .7v.    Because the voltage is one-directional through a diode, you have to put a pair in reverse direction to make both directions work.

To drop more peak voltage, you pile on more and more diodes until you get what you want.    The diodes in this case can be pretty small.   You'd want a bigger rating for a power supply.

Before I got my transistor throttles, this was my 'go to' method for speed-matching consists under DC - you take your fastest locomotive in a set and see if you can bury 2-6 diodes like that somewhere in the shell to slow the motor down.    It works pretty well.    My 'last install' of that was knocking down an old Atlas SD50 chassis so that it would pull at the same speed as a Kato SD45 chassis.   I still have some of those diode piles in my powered boxcar units to match their speed to the locomotive they run with.

But under DC, it's a pretty tried an true method to drop voltage only.   Resistors in series behave entirely differently, and under load, will simply get warm, or hot, or burn out depending on their rating; and they also don't behave the same as the voltage climbs as load comes off.  Diodes, or a pile of them, behave entirely differently.

[cjp53]

Thanks this is cheaper than spending $100 on a new power pack.

[cjp53]

A friend of mine is a electronic person who is in the TV and Radio equipment business.He's going to make me a couple reducers one for each power pack.I sent him the link of the  MRC part listed.So I should be safe to run my Kato's.

[cjp53]

Friend has it done already! Picking it up later tonight.

[peteski]

Friend has it done already! Picking it up later tonight.

Those diodes are probably 10 cents each when purchased at an electronic parts distributor, so having it built by someone in-the-know will save you some dough. 

But if you were were to run DC only models (no decoders) then there is no need for that voltage dropping circuit.  DCC decoders are made DC-compatible, but their performance is usually not  as good in DC as in DCC.  DC model in decoders was supposed to mede transition from DC to DCC easier (not a long term solution). 

Some newer models are only produced with decoders. But t maximize performance, modelers who still run on DC often pull out those decoders and convert the loco back into the old-school DC-only model. 

[nsbob]

If you are looking for a DC throttle to run two trains at the same time on different tracks, I highly recommend the MRC Tech II Dual Power 2800.
My club has used this throttle to run Atlas, Kato, Fox Valley, and Bachmann DC locomotives flawlessly on DC powered TTRAK modules at several two hour long train events .  The output power listing on this throttle is 10.5 VDC.  It also has an AC Accessories outlet if you need it.   Maybe your hobby shop friend can pick up one for you.
Good luck;
NS Bob

[peteski]

If you are looking for a DC throttle to run two trains at the same time on different tracks, I highly recommend the MRC Tech II Dual Power 2800.

Bob, are those true dual throttles, or they share the same transformer internally?  What I'm leading to is whether for example they could be used with common-rail block wiring method, or will that cause a short when the direction switch in each throttle is set in opposite direction?

[cjp53]

I looking at price,after just getting this Mikado don’t think my wife will be happy if I drop another $100 plus at this time.This is a birthday gift from her. .I passed word to our local train shop to look out for one but the shop is closed due to the virus.