TMCC problem in forward only

My top suspect would be the flywheel encoder, because that's a symptom of the encoder not reading.  Sometimes RPM encoders will read in one direction and not the other.

If you have an Odyssey switch, turn it off and see if sanity returns.

Thanks John, you have been a great resource.  The only switches I see are those that I have seen on all Lionel engines, the run-program and smoke unit switches.  Where would I look to find an Odyssey switch? The Lionel replacement parts section does not offer any kind of encoder device for this engine.  So I guess I am still stuck as how to make this engine run forward in TMCC without going into orbit.

I'm wondering if maybe this could be a bad R2LC.  If there is no Odyssey switch, this is one of the early Odyssey models and it would be enabled in conventional mode.  There is some raindance you can perform on these models to turn off Odyssey in conventional, I can't seem to find a book with the exact sequence.  I'm wondering if Odyssey is working in conventional mode?

Do you have another TMCC locomotive you could try a R2LC swap?  That would be a quick plug-n-play test.

Since it runs in conventional mode, the communication between the R2LC and the DCDR-S board is obviously working.

Well, it's a pulse train coming in on the forward and reverse lines to the DCDR, so he'll have to have a bit more than a meter.

Since it runs in reverse, the power supply would seem to be there, it's not switched.  However, the forward and reverse controls are a PWM signal.

The Common 5VDC is the source to the MOC 301X series optical isolator.  The return pin for the LED source in the MOC goes to the Fwd or Reverse pins which are PWM.  So yes it still can be tested.  If both pins on R2LC are providing continuity for the signal, the next component is the Optical Isolator, then the Transistor the OI triggers, then the SMD resistor path to the TRIACs or FET, then the FET themselves.

I have been mapping and repairing these for quite awhile.  There was an old post on the former board where a gentlemans DCDR for a N&W engine was repaired via the forum by the troubleshooting techniques I have post and component replacement.

No special test equipment needed other than a good VM.  G

So what is your best guess, a new R2LC or a new DCDR?  Are all R2LC boards the same?

The R2LC boards come in various firmware versions, but a later version will probably work for most engines.  The ones I've seen are C08, C11, and C13.

Mike, I couldn't tell you which to try.  The best is to swap boards with another engine if you can.  The R2LC is $40-45, DCDR are about $100 as I understand.

If you have a tech near you with a board tester that is the best way to go.  G

I think Boxcar Bill has discount prices on the R2LC if it's necessary.  If he happens to need a DCDR-S, I have one that is the EM2 firmware version.  I'll certainly let it go for less than $100!

You guys are great, thanks for the input.  I bought this engine on ebay for $159 knowing it had a forward speed issue.  I took it to an authorized Lionel repair station and they fixed a shattered flywheel ring, actually I believe they put in a whole new motor.  This cost me $100.  Apparently they did not do anything for TMCC running, but at least it now ran ok in conventional.  I may have to be satisfied with the conventional operation only.  It is a nice 4-6-0 that looks brand new.  l tried another R2LC board from another engine but nothing worked at all, probably wasn't the right unit for this engine.

What version is the R2LC in the problem locomotive?  Did you try that R2LC in the working unit?