Strange LM-3 problem

[Dean]

I have been upgrading my inferior DCC decoder-equipped engines with RailPro decoders. But I have run into an unusual problem.
I am upgrading two Stewert/Kato ( mid-1990s vintage ) F7s. The F7-A was upgraded a few weeks ago with an LM-3. This past week I upgraded an F7-B with an LM-3. Both engines run great with the upgraded decoders, except for one problem. When I MU the engines the F7-B gets lethargic. Top speed is about one-third of what it should be and acceleration is also reduced. I went through the settings multiple times but found nothing. When not MUed, both engines run as expected.
I exchanged the LM-3 in the F7-B with a new, out-of-the-box, LM-3. Same problem.
Now it gets interesting: If I make the F7-B the lead engine, both engines run fine when MUed.
I haven't been able to do much of anything on my railroad for almost two years. So I decided to start my upgrade program by installing the new program in my HC-2. Version 2.09. I haven't noticed any problem since the HC-2 upgrade, but I am going to double-check other upgraded engines.
I'm thinking of re-installing the software in my HC-2. But to me, it seems like the problems are in the LM-3s.
I run 98% of my engines MU'd. The only single engines I run are some switchers, and they are DCC.
I'm baffled and confused.
 

[KB02]

My first thought would be to swap the LM's from the A to the B and vise versa and retest. but since you've tried a whole new LM, that might or might not prove anything. Still worth a try?

[KPack]

Are you running the two locomotives uncoupled to see this happening?  If so, that is not a good way to measure list sharing.  When uncoupled, if the locomotives run at the same speed they are speed matched.  Load sharing is different.  When load sharing, the locomotives will run at different speeds in order to spread the load felt by the locos equally across the consist.  So when the B unit is following, it's likely sensing that the lead locomotive is not carrying enough of the load so it slows it's speed down.

On the flip side, when the B unit is in the lead the trailing A unit is sensing that the lead unit is pulling too much load so the A unit is running faster (and appearing to run at the same speed as B). 

This is all likely happening because the B unit is drawing more amps when running when compared to the A unit.  Could be anything in the drivetrain, motor, etc.  I have several locomotives that exhibit this behavior because of various amp draw differences.  It all evens out when in a consist.

You can run the FMLC setting again on both if you want, and that may help ease the differences between the two.  If you really want to experiment you can adjust the FMLC manually up and down a bit to see how that affects running in a consist.  I don't typically recommend doing that, though I have done it to a few of my models to fine tune things.  Nearly all locomotives will work perfectly just by seeing FMLC automatically.

Kevin

[Dean]

I tried swapping the LM-3 to different engines.
I manually set the stall current in both engines to the same value.
But, when I tried to run a pre-established MU setup, I started having the same problems. I started getting weird messages ( from my memory: cannot connect as a follower ).
The controller started doing weird things too.
I believe the HC-2 is toasted. The upgrade must have scrambled something in the firmware. I let the HC sit all night without the batteries in it. I put in new batteries and now the HC is acting normally, except for the MU function.
I might try the one-hour reset that was mentioned in another post.  After that, I'll send it back to Ring for repairs.

Thanks for all your help.

[KPack]

Yeah, those symptoms don't make any sense.  It does sound like something got scrambled in the HC.  I've had that happen before, but it was because I was testing beta software.  Definitely check with Ring to see what they say.  They may just have you send it in for a factory reset.

-Kevin

[William Brillinger]

You could also try reloading the current HC program.

[Dean]

Thanks for all your replies and suggestions!
I installed the HC program for the third time. I installed new batteries after letting the HC sit overnight with no batteries installed. I set up a MU with three 1990's vintage Stewart/Kato F7s. I set all the stall currents to 320mah. I also set all the accel and decel settings to the same values.
The MU setup is working fine now. These engines have LM-2s in them. A second MU setup with LM-3s installed ran fine but I didn't have time to really test them. If they run fine I will test a MU set up with a mixture of LM-2s and LM-3s.

Again, thanks for all your replies and suggestions!

I still don't trust my HC-2.