I tried to bench test an LCRU (1) and found that everything worked normally on a bench setup with the LCRU driving a freshly cleaned Pullmor motor laying on its side. I always do bench testing with jumpers, so pardon the mess when you watch this video. The problem I have is that the motor sounds like it has a chipped gear, just randomly catching – and the speed seems to drift as much as + 25% over a period of a few seconds. I then ran it conventionally by just unplugging the command base (but still using the LCRU as my reversing unit) and discovered the chipped gear sound is gone and the motor runs at a smooth and steady rpm!
Thinking this might be the LCRU, I set up a brand new (from Lionel) LCRU2. Same exact problem. So I grabbed another brand new LCRU2 (also from Lionel), same problems.
It appears as if the LCRU is possibly sending out very short bursts of full voltage, making the chipped gear sound as it slams the motor with full voltage only to be reduced to a much lower setting just a few milliseconds later. Thinking that may be caused by electrical spiking, I added a pair of (brand new from Digikey) non-polarized 10uf caps, one to each brush - I know, shoulda done that anyway! No difference!
After carefully marking the slug positions on each of the tuning coils, I tried to tweak them thinking they might be on the ragged edge of being mistuned. All 3 LCRUs lost communication at + ¼ turn and at – ¼ turn, so I re-centered them all to their factory positions, and checked that off my list.
I then swapped command bases with another known good one (including a new wall wart), same problem. So I swapped CAB-1 controllers with another good one, same problem.
I started looking around for flickering fluorescent lights thinking maybe that was the culprit – no fluorescents in the room, just LEDs everywhere I looked. I even turned off my temp-regulated soldering pencil, no difference. The only things I did not change out in this setup were my ZW and any/all of the jumper wires – didn’t seem like they were suspects given the fact that all ran well on conventional. Nothing else is running other than room lights.
The only possible cause I can find left is the rat’s nest of jumpers, some of which may be acting as antennas and introducing noise into the equation. The only way to prove this will be to install the whole mess into an engine and carefully dress the wires. I will do that this coming week, but in the meantime I was wondering if anyone else has seen this happen and if they found a guilty culprit?
One last possibility … just throwin’ this out there, but maybe ALL LCRUs normally do this, but it goes unnoticed 99.9% of the time, because the engine is vertical and has at least the load of its own weight to dampen out these glitches.