I'm working on a almost new 18052 Lionel PRR 238E that won't go forward. It will run in reverse but not forward, both Command with a Cab 1 and conventional. All other functions work to include Railsounds. I've tried everything I know, even going 'outside the box' checking Momentum, stall, boost, max set speed, etc. Reverse runs fine.
Looking for ideas before I swap out the $90 LCRU-2 board.
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Could it be a bad run/program switch?
Doug
Its been a while. But, it is possible in conventional to lock the engine in one direction by setting the run switch to program. I'm assuming the switch is in the wrong position or physically reversed the way it is mounted...
Will it go to neutral in conventional? If it does, that would probably rule out the switch being set in the wrong position (or shorted or opened?)
J White
I don't know what the -2 means in LCRU-2, but if you go to Carl Tuveson's webpage at www.tuveson.com and find Cam Bickel's info on TMCC Schematics and Technical Theory, you will find an LCRU schematic.
There are two "direction" optocouplers that are used to turn on two pair of output triacs, one opto and its pair of triacs for each direction. First, verify that the voltages to the optos are coming on in forward and reverse.
If all else fails, reverse the motor leads and always go forward!
The Run/Program switch works as it's supposed to, in both Command and Conventional.
In Conventional I do get neutral. Reverse-Neutral-No forward-Neutral-Reverse etc.
Dale, thanks for the info. I'll go to the web page and troubleshoot from there.
I thought about reversing the motor leads, but with the electronics, the headlight would go out. I'd have to hot wire it.
Swap the headlight leads too. Most likely it is repairable. Check solder joints on the SMD resistors in the fwd motor drive circuit. You can actually jump the isolator and if it runs forward that validates the H Bridge Triacs as good. If not may have a bad Triac.
The -2 means it has modular plugs for wiring vice soldered motor leads and such. G
The symptoms suggest you have either a bad triac or a bad opto-coupler. Both are easily replaced.
Dale Manquen posted:I don't know what the -2 means in LCRU-2...
There are two LCRU models, the first version has pins for the connections, the second uses the 2.54mm connectors that Lionel uses on other TMCC stuff. The schematic you referenced on Carl's site is for the first version with the separate pins for each connection. I'm not entirely sure if anything but the connections changed, they seem to have similar capabilities.
A fair amount changed between the LCRU 1 and 2.
Besides the connection method you noted, the LCRU 1 has a socketed microprocessor, and the software is not programmable through the CAB-1 for changing locomotive type/features.
The LCRU 2 features a soldered processor, a slightly revised component layout, and the ability to be programmed from the CAB-1.
TRW
Correct you are, I forgot about all the changes, I don't do much with the older TMCC stuff. 
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