Smoke control with LCRU

Pete, you can always wire it direct.  It'll always be on, unless you wire in an ON/OFF switch.

 

That's what I did when I added TMCC via LCRU to my Lionel 0-6-0 switcher.

John, I understand that is an option but if I control it with a handheld that would be  preferred plus I'd like to learn a little more about LCRUs.

 

Pete

Pete, Depends which LCRU you have.  The DD site use ot have the legacy instructions. Not sure if it still is up.  If so, you will find what you need there.  The first version required hardwire connections to control the functions.

 

For steam pin E was headlight and pin F was smoke.  To hardwire for steam, Wire N black and Violet L went to run program switch.  Wires M white and B Black were tied together with chassis ground.  This sets up headlight on always and smoke.

 

If M White goes to ground, and B black is unconnected then the board is a diesel with directional lights on pin e and F.

 

Later LCRUs used the soft code.   G

G, I did some more poking around. It turns out I have an LCRU2 which may explain the descepancies from Carl's web site. It appears the smoke resistor is connected to one of the small triacs. I get continuity from one leg of the triac to the smoke resistor. I will probably swap out the triac though I am not sure that will fix the problem as ohmmeter checks show it matches the 4 other triacs next it. I also measured zero volts across the resistor in both conventional and command mode even after hitting AUX1 9 many times.

The manual does not show any extra codes that have to entered after setting engine ID though hitting AUX1 4 does blow the whistle a second time in program mode.

 

Pete

You sure there is no switch in series some where?  Do a diode check on the triac.  G

Have you tried a lamp on the triac output, just to see if it's actually switching on and off?  For the little TO-92 triacs, the smoke unit is a pretty heavy load.

 

Try some of the other steamer programming codes and see if you get any different results.

 

No switch visible or mentioned in the manual. Actually I can can follow the wire directly to the board.  I have the shell off and a voltmeter across the resistor, zero volts AC or DC. I would expect some if not full voltage in conventional mode at least.

I was surprised to see the resistor tied to one of the small triacs. IIRC they are rated for about 1 amp so they must be close to their limit. I'll swap out the triac and report back. If that fixes the problem I may mount a large triac off the board.

 

Pete

Pete, The diode check is the easiest way to test those standard triac.  Sounds like it is open and not conducting, as long as you know the other end of the smoke resistor is grounded well.

 

The 27 ohm resistor limits the current.  So 18V/27ohm (less the power factor for AC) and your under the 1A limit on the Triac.  Also it may be half rectified AC going thru anyway.  Don't know for sure.  Pretty easy fix.  G

If it's like the R2LC, it's half-wave normally and full-wave for "boost".

Well my instincts proved right. The triac wasn't the problem. This time I did what I should have done before swapping the triac and checked the gate voltage. nada, zero, zilch volts. I can only assume the microcontroller has a bad gate unless someone more familiar with the LCRU2s can point me to an intermediate device that may have failed.

Looks like Johngg1's solution for this engine tying the smoke unit to the pickup roller via a switch.

 

Pete

I came up with a circuit to turn off my smoke unit when the train was stopped, maybe you need one of those if you're going right to the pickups.

If the smoke unit gets voltage in conventional, it would seem the logic path to the smoke unit from the uP is good, I'm wondering if a reset would have an effect.  In conventional mode, the uP is turning on the smoke, apparently that's working.

LCRU2's will pulse power to the smoke unit when at idle. This is because when LCRU2 was developed we only had mechanical smoke units. No motion = no airflow. So the resistor received power on and off (half wave perhaps, not certain) to prevent the element from burning up. Hence LCRU (1 or 2) is not a viable option for a fan driven smoke unit without the addition of a relay. This means too much stuff to cram inside the loco to make it work reliably. So, even an LCRU2 with cab light settings will run a smoke unit, but there is no "smoke boost" and smoke is anemic unless running at a high medium speed or full tilt.. LCRU's should be used on non-smoke unit AC motor applications for optimal results (from a conversion aspect anyway). Mikr

Mike are you saying I won't see voltage to the smoke resistor unless the engine is running? Could it be pulsed by the chuff switch? Maybe the switch was closed when I saw smoke that one time. Given the way the tether is mounted to the cab roof (NYC Commodore Vanderbilt with Pulmore Motor), its not easy to move the engine with the shell off unless a lot of disassembly is done.

I did install a switch and tied the resistor right to the track. As you say even at a full 20 volts the smoke is anemic and that with the resistor sleeve removed.

I'll chalk this one up to a learning experience but stick with later DC motors and modular TMCC in the future.

 

Pete

Mike's answer makes prefect sense, I don't have any LCRU2 equipped locomotives, if I run across any, I have a little more information now.