Trying to grasp the technical side of the hobby!

 "Does the DCRU unit have components that do this conversion in addition to causing the engine to have a neutral, forward and reverse function? In effect, does the DCRU board serve dual functions as both a reversing unit [with neutral and forward] AND a DC to AC conversion to that my 12 volt DC motor power source for the engine can be used on an AC powered track?"

  Basically yes. A DC powered loco can run with just wires from the trucks to the motor   ( in practice they add extra circuits for lights etc). I guess there's some reason 3 rail trains stuck with AC power but I'm not sure what it is :>  The advent of DCC and other command control systems makes the whole question kinda irrelevant these days, like modern cars the model locos get too complicated for owners to troubleshoot but they do run better and do more fancy stuff.. .....DaveB

To allow horn/whistle and later bell activation by injecting DC offsets into traction power.

---PCJ

Actually, a 3 rail Lionel/MTH locomotive cannot just run with wires straight from the trucks...

The electronic board will have a bridge rectifier circuit in it to change the AC current three rail trains utilize into DC current which all can motors use. Running DC can motors with AC electrical supplied will ensure burn-out of the can motor at some point. They will usually just sit and hum until it gives up and burns out....

It's actually worse than that.

AC will fry all the electronics in a modern engines circuit board.

So yes, D&H 65 is right, they convert the AC to DC, and they do it in varying voltages.

The Motor uses up to 12 VDC but the circuit boards are mostly 3VDC now, some older ones were 5VDC.

You don't give the number of the engine so I can't be specific at all.

A DCRU-WD board is Lionel Specific but even within those there are variants.

I suspect the engine should be referred to a repair person with Factory training.

I'm an electronic engineer and I won't touch it because I can't get the documentation needed to do the job right.

I send my engines in to be repaired Or I replace the entire board.

Simple stuff like smoking cars I will fix, no big deal, but engines are a whole higher level.

To enlarge on what has been said, all semiconductors in all electronics, not just our trains, needs DC voltage to operate. Any AC powered train, computer, etc. must first convert the AC to DC to power the electronics. A conversion to DC powered track can not be done, as all the sounds are activated by a DC pulse. To do so would obsolete all our trains with whistles, horns, etc.

Larry

DocTony,

I grew up with prewar Lionel Trains. To this day, if it's newer than 1935 I'll pass. I prefer the older trains because they are simple. And yes, they remind me of a time when things were simple and easy.

God Bless,

"Pappy"

I agree with you, Pappy.

The 'old days' (before electronics was incorporated into almost everything produced), spawned many backyard/basement mechanics. Almost anything could be repaired by them, like our pre- and postwar trains. With the advent of electronics controlling more and more of everything, these mechanics are all but history. Mechanical devices are easy to see operating, and to diagnose and repair when they don't. Electronics are a 'black hole' to most people, and as such, are left to those that have the advanced skill and tools to repair. Today, many hobbyists who could overhaul an older engine, are left to sending their product out for repair. Electronics is nice, and adds features unheard of in the past, but it comes with a price-generally not field repairable by the owner.

Learning the 'technical' aspect of repairing our older equipment is easy, and there is plenty of documentation to help you. Repairing electronics is just the opposite, and best left to the experts.

Larry

There is a lot of complexity but there are people who understand it and its really remarkably reliable, and good-performing.  

And its not just trains.  Cars, appliances, and or course, computers (I'm typing this on the 21st equivalent of a typewriter, in a way) have evolved and have features none of us - at least me - would ever think of giving up.  The cost is a lot of electronics that makes them nearly impossible to fix without diagnostic equipment and skills, but they are reliable and dependable in general.  

I much prefer today's toy trains.  Maybe because I am an EE the electronics doing bother me, but I don't try to fix most of them myself anyway. the performance is so much better in so many ways.  I would no possibly trade to go back again for the simplicity of repair.  

"Actually, a 3 rail Lionel/MTH locomotive cannot just run with wires straight from the trucks..."

   If it has a DC motor a three rail loco could run on DC current with just wires from the trucks to the motor. It just won't be able to use the sound, lights, or other features. Reversing would be done with the power pack switch instead of thru the sequencer. The current doesn't care if it's going thru 2 rails or 3 rails or overhead wires..DaveB 

Thanks to all who responded both publicly and via email! Armed with new information [and noticing that my original post regarding DCRU-WD has already been listed on the internet Google search engine], I proceeded to resurrect from the dead an older Weaver GP38-2 diesel with a new DCRU-WD chip board and the diesel came back to life! Mind you, less than a week previous, I wasn't even sure what the acronym "DCRU-WD" exactly stood for and thanks to multiple public and private input coming from this forum, and an email to QSI which was answered almost immediately, I was able to salvage the engine and see it come back to life and do its thing on my 3 rail O-gauge tracks.

Lessons learned: While the acronym DCRU-WD stands for "Directional Control Reversing Unit -- Williams Diesel", I learned that the DCRU unit can be used for other makes as well like my Weaver GP38-2. I started the repair last night but the learning process was ongoing and I initially made one cardinal error which I'll share. It's of course SOP [throw back from my US Army days -- Standard Operating Procedure] to first check the DC motor using the old 9 volt battery trick but it's very easy to forget that when you switch over to the test track and start tinkering with the wiring of the DCRU using those small but very handy multiple test leads and very low transformer voltage, a typical DCRU, ==WHEN WORKING==, will default to neutral and therefore when one is testing the wiring [as wiring color VARIES from engine to engine], you may in fact hit the right combination as to what goes where but since the unit defaults to neutral [and you might have temporarily disconnected any train lights to separate the cab cover from the innards of the train itself you're working on and thus in any 'movement' not drag the cover along where the lights are located], you may see nothing happening as you probe and test for 'movement' unless you TAP the test wire(s) to get past the DCRU default neutral and get the unit to either move forward or reverse! In its neutral mode, you'll see nothing but this is entirely normal whereas movement is guaranteed if a 9 volt  battery is used in the DC motor testing phase since that's pure power [the 9 volt battery] and there is no 'neutral' if you see what I mean. On the tracks tho' and using transformer AC power and assuming the DCRU is wired correctly, you must allow for the default neutral of the DCRU! Guess who initially forgot that fundamental concept!   

Then it was matter of connecting the DCRU wires in test mode and, when finalized and checked thoroughly, getting out the solder gun. On the QSI DCRU unit I had in hand and which could handle two DC canned motors, I only needed one set of DCRU wires since the Weaver GP38-2 was a single can "engine."  The YELLOW wire went to the DC motor terminal marked "1", the BLUE wire went to the DC motor terminal marked "2", the ORANGE wire went to the 3 soldered together red wires coming from the trucks and the BROWN wire going to the 2 soldered together black wires coming from the trucks. I also made certain that the chip board did not touch anything on the metal platform where the DCRU sits on the 'double sticky' foam backing EXCEPT for the DCRU bottom mounted rectifier [on this particular QSI DCRU chip board] where the QSI instructions said that this [the bridge rectifier] should in fact make good contact with the metal base the chip board sat on within the engine cab so as to dissipate the rectifier's known generation of heat. Nothing else should touch any metal, the directions said, except for that under the board rectifier. With all the temporary test wires in place, I put the engine on a test track using my smallest wattage transformer, applied power, the default neutral first came on, then a tap of the last lead lead brought on the forward and subsequently the reverse mode and all was well. Of note, QSI said that if the finalized sequence saw the engine initially go to reverse rather than forward, just change the position of the BLUE and YELLOW DCRU wires that go to the DC motor #1 and #2 positions. 

This is the first time I've ventured into tinkering with modern day electronics and it's a far cry, technology wise, from a then 9 year old kid back in 1953 [!] when on Christmas day that year I was presented with the Santa Fe 2343 ABA diesel set [with a KW transformer and some freight cars and a brown Lionel caboose] and that Santa Fe ABA set continues to run on my lay out [dedicated room with 13 individual tracks on 3 tiers of 12' X 16'] to this very day! Still has the original bulbs too and only a new horn was installed some years ago. It still pulls like a champ! But, as I stated initially, I wanted to do and learn more other than basic O gauge train maintenance and thanks to folks like you who share their technical experience and expertise, I can do just that ... slowly, to be sure and my own errors and botches built into the learning process,  but surely! It's a challenge! I thank you all for sharing your knowledge! BTW, and talk about learning from others, how many folks out there believe they have a "dead" engine that has ProtoSound 1 [PS1] only to find out that the "cure" could be nothing more than replacing the PS1 8.4 volt rechargeable battery with a fresh one or, indeed, testing the PS1 equipped train with a 9 volt battery just to see if it comes back to life and learning in the process that it's not "just" railway sounds in PS1 or PS2 units but if those boards do not function, the train doesn't function either and all you get is a series of dings or clangs where the cure could just be the 8.4 volt battery which power the older PS1 units! Or forgetting to kill the transformer power completely on PS1 units and then re-apply power to get the PS1 unit into its standby mode ... and movement! Nice that in PS2 units, QSI developed a plug in charger! Whew! Long and windy, I know, and nolo contendere to the charge would be my plea at Bar, but then too, if some reader somewhere may benefit from the recitation, hey, where's the problem! ;-)    --- Doc Tony                  

Ooops! Yea I've there before with tests. Glad to hear issue was solved. When I read "where's the problem" at the end, I thought I missed something for a sec. Your basic theory level eludes me, you claim "ignorance", but logic chase, and basics seem great. Basics haven't changed to much since tubes. I bet the newer smaller packages just have you spooked a bit. I remember my first micro repair, I about had to change my pants when I saw the micro's on the board.

 Yes, you will have to learn the extra stuff for each train, or electronic component, to control it well. But basics haven't changed, and size, reliability, price, performance, and option availability will be the outcome.(not that post war isn't reliable, PW is my first choice). As was pointed out many newer items knock at least some power down to low voltage dc after the ac cord goes inside. In other electronic repairs, a pull, and replace policy on micro boards is almost a given for low down times/repairman time-vs-cost. Even on boards with "normal" sized components, I often checked basics, and tossed them into a parts bin till I had enough to Frankenstein a good one, because a few "chips" can be more $ than a new board. I'm not sure I would make as much effort with todays micro electronics.

Hi Doc Tony • Trying to grasp the chaos of wires. • Technical Side.

    My issue is tracking down all the wires, if an issue comes up. I have 10 Engines on Lionel Cab #1 and 16 Engines on Mike's TIU / DCS Remote Control. The best part of all this is one engine on LionChief Plus.

   If a problem comes up on the TIU / DCS, I could have 16 engines go down. If a problem happens with LionChief Plus, only one engine goes down.

   All the wires in this photo have labels and match up to the technical drawings to make it all work, but it looks like chaos.

    Back in the day I used to build a lot of Heathkit projects. Even did a color TV, so I do have a little understanding of electronics. Wires can be organized chaos.

  Four bricks, one for each main line & one brick for accessories, not seen in photo.

  Click photo to enlarge.