E-Unit Schematic and Theory of Operation

Lionel E units are a source of many problems and frustration. What part did you replace  ??  First thing I do with them is clean with CR electro cleaner plus make sure the fingers are not bent or broken. Just cleaning them has solved some problems for me but if the parts are badly worn then replacement is necessary.

Paul's document pertains to electronic e-units.
I downloaded a copy for my files.

Thank you!

Olsens' parts has the entire Postwar Lionel service manual posted online, along with a lot of other valuable information. It can be found here: Olsens Library

Paul was able to diagnose the problem and replace board level components on a Lionel electronic e-unit.  He posted to share his acquired knowledge (THANKS AGAIN)!

Nice write-up Paul.

Dave

There was a two-part how-to clean / refurbish E-units video on You Tube that I viewed several years ago. It was excellent, both content and production quality.

May still be there?

Did you read the document he created and posted?  It's possible we may need his help more than he needs ours!

Pete

Absolutely.

Great job Paul. Thank you.

WOW, that is an impressive creation, you must be a technical writer or an engineer!

Paul,

If you ever do something similar for the early Lionel (MPC) sound of steam boards, I hope you will post it. 

OK, I been repairing trains for almost 40 years, I'm impressed. Too much info!

 So what is your next project to reverse engineer.... Lionel Legacy circuits? ()

Wow! How do you go about doing this?  How do you know where to start?  As a side note, regarding the electronic e-unit, who gets credit for the design?  I've never seen any articles as to how it came about and was first used by Lionel.

Very impressive and professional paper. 

-rog

As someone who was an electronics repairman, I am VERY impressed with the job he did creating it!

Very sharp kid!

Rob

Yep, that's quite a nice piece of work!

Yes, I saved it, that's worthy of being included in my Library.

That's the truth, very good document, quite impressive as well. Maybe when we have a problem the manufacturer's can't fix we should send it to Paul! Or maybe one of them should make him an offer of employment, PDQ.

Thanks for posting this information. As others have said, please post any more that you might do in the future. Many here will appreciate it. 

Very impressive Paul. I look forward to your future contributions to the forum.  

Paul,

You are one sharp young man. Don't be surprised when folks start lining up at your door. With all the electronics in trains today your services will be needed.

Sorry! I almost forgot, "WELCOME TO THE FORUM" . Hang on, you're in for one wild ride.                                                                                                                                                                                                      

I don't have any Lionel electronic engines, but I do have some Mand K Line. Can the e unit be re wired to neutral, forward, neutral, reverse? My K line engines also are forward first, which I'm not happy with. 

Don

Paul, welcome to the forum.  Even though I prefer my trains to be powered by springs rather than electrons, professional curiosity prompted me to check out your paper... and I was very impressed.  Back when I was a bench tech doing component level repairs, I would have loved to have had well written, logical technical papers like this to guide me.  Many thanks for sharing it with the forum!

Romsk,

Nice paper...should be useful to many.

Welcome to the OGR forum!

That was a very well executed dissertation on electronic e-units.  I doubt Lionel put that much effort into their original desgin.

Just for fun I'd like to send you a horn board bell to see what you think of the solid state methods of decoding a positive and negative offset.

Regards,

Lou N

What an excellent piece of work.  Thank you and welcome!

Jon

One additional comment...I agree with GRJ that this work is a keeper.  And remember, both of us have brought successful electronic products into this train market.

Lou N

Lionel did not do the original design. The original design was published in one of the model railroad magazines back in the 70's. All of the current electronic E-units were spawned from this design.

As strange as it may seem to some people, Lionel did not invent EVERYTHING. There are and were many, many talented engineers on the model/toy train hobby. Only a small percentage of them worked for Lionel.

I am not picking on anyone in particular, so please do not be offended, but I cannot comprehend the idea that in the toy train world, one particular brand is the be all and end all, and always was and always will be. That is just not so. It is and always was a fierce competition of many brilliant minds and many companies trying to outdo each other for market share and the customer's dollar.

All,

Thank you for the warm welcome!  And thank you all for the feedback - the free sharing of knowledge is what it is all about.  Oh yes, I have a lot to learn and will help anyone who asks.

I am glad that someone is finding use for this document.  "I R an engaeer", and I have the coffee cup to prove it - with the handle on the inside the cup [laugh].  I am a high speed digital/FPGA guy, but now I do a lot of test software for automotive radar.

It took about an evening (while watching TV) to trace out the circuits, then a few hours to clean up the schematic, a couple of hours for the layout and about a day to document it all. Then about an hour to find the problem.

The problem on my E-Unit was there was no current through the Q2 base, so it stayed cut-off - like one pole of a DPDT switch that is stuck open. 

Lou N:

Yes, send me the Horn Bell and I will take a look and write up what I find.  Write to me via my website to arrange this:  http://www.paul.romsky.com/  paul@romsky.com

When you think how long it took me, imagine what document the OEM could have produced, I could have had o-scope shots of all the signals, but I thought that was a bit much, but I can add them if anyone asks.

rail:

Yes, some cut-and-jumper wires can make the unit start in any state you wish.  Send me details via paul@romsky.com and I can send you instructions.

WindupGuy: When I was in the US Air Force, we had all sorts of documents like this, when I hit the commercial world I didn't find the level of detail, so I guess I am like you, having a good document on hand makes a great asset.

SWANKO:

You start by assigning each part a reference designator (R1, Q2, etc.), then follow the circuit traces, and draw a rats-nest of what connects to what on pieces of paper.  Then you reorganize which components are related to each other, then you try to read part numbers off of the components. Then describe the circuits you see and clean up the schematics.  Lionel gets the credit for the design, all I did was fill in the gap on missing detailed documentation.

Paul

Thanks

RoyBoy,

I just assumed it was a Lionel design because it came from them, but whoever designed it should have put their company name on it.  On mine just about all that was printed on it was the Lionel part number.

The original designer put the schematic in the magazine so everyone could use it. Everyone has. 

None of that takes away from the great job you did reverse engineering the unit and posting it for everyone to see.

That was a great job and we all thank you for that.

My rant should do nothing to lessen your effort and accomplishment. Thank you.

RoyBoy,

If you can send me the magazine issue number, I will look it up and give the original designer the proper credit.  I was impressed on the simple elegance of the design.

Thanks,

Paul

repairtechnician,

Yes, sure.  Are they single layer circuit boards? If they are not (multiple layers) then the only way to do that is x-rays and milling away layer by layer to reveal the traces at each layer - a destructive process.

Send me a photo first paul@romsky.com and then we can discuss.

Paul

I was always diligent in my model railroad reading so if you can recall the magazine that had the e-unit article i would appreciate it.  Interestingly, the IC described was used in a number of different e-units.

And I am certainly not offended.  There is a relatively small group of electrical engieers in this industry that do keep in contact with each other and help each other. 

Please note also that many designs came from SDK when Lionel went to China.

Lou N

I will follow up over the weekend.  You will find whistle/bell activation a fascinating topic.  It is a short course in low pass filter design.

Lou N

Holy crap!  That is awesome.

Wow, Lets hope he's involved with the writing, or will be teaching soon.

I've seen some real messes. No important stones left unturned.

This should be standard reading for those stepping into semiconductor circuits here.

Only one thing, tiny little bitty whiny thing, I wished you would have hit on more, in passing. The diodes, I think were helping keep the base saturation in line on your problem Q, no?   

Saved in train documents!

Looking forward to a building a new file named ROMSKTECH

Adriatic,

Q2 was "blown" in my case.  The only diodes in that circuit are the isolation diode CR5 and the AND gate diodes CR9 and CR12.  Are you talking about the Q2 Base-Emitter junction which is in some effects acts as a diode? Hence the symbol has a diode inside it.

Paul

Paul

That is amazing!

Peter

I could have explained the h-bridge transistor operation a bit more. I will expand on that inthe next rev.

Nice work!  Welcome!

I didn't realize the base emitter junction was already internal there, I just kind of scanned that part of it, and would have gone right to the base, as my repair beginning check on the boards before fully pulling the Q (coin-op). It was written more than well enough, I just went a bit to fast I guess. But that was what I was talking about. Took me a bit to really figure out why they where there.(mostly self taught, on the job), I guess that's me projecting . But the good writing had me wound up . Easier to read it, than to have to figure it out alone. 

The balance of info was nice, well timed, and explained (sans reader errors). And not overwhelmingly over ones head (like most engineers tend do). If you can do that regularly, I'm sure somebody is looking for you to reverse engineer their designers mess for the service techs.