RailPro > RailPro Specific Help & Discussion
Bad-ish LM-2S?
CPRail:
Happy Holidays Gang,
I decided to complete a long lingering install today using a LM-2S that I purchased used. I bought a pair of them and the sibling has been happy happy, so I was expecting no issues.
The install is in an old Athearn Blue Box SD40-2. I did the initial hookup and while trying to do a motor load test, realized that the Athearn motor has seen better days. The LM was getting warm and I couldn't get it the test to complete twice without getting an Overload message.
Thankfully, I have a pair of old Proto Power West SD45 re-powered chassis' sitting around, so I re-motored our candidate with one of the Mashima can motors PPW was known for. That solved the motor issues!
I'm using an Athearn DCC Quick Plug board, with wires to the trucks, one soldered on the big truck tab, and one soldered to the opposite side ala current Athearn/Genesis wiring. I also have a bridge rectifier soldered in on the red & black wires with a KA-4 connected in. Cumbersome, but it is a LM-2S so needed.
Hooked up everything again and started some test runs. Got a nice low motor test, so started tweaking the various settings. After running it back and forth, I started smelling the distinctive smell of unhappy electronics. The LM-2S was also feeling warm. Uh oh...
I have a bunch of LM-3S modules waiting on other installs, so I unplugged the LM-2S and plugged in a LM-3S. Everything went back to happy happy, with no smell.
Odd thing is the Info page on the HC did not say anything of overheating etc. Temp was in the middle of the range.
The LM-2S worked fine, but the unhappy electronic smell without the shell on has me worried. Is my LM-2S buggered? How do I tell?
I don't want my railroad to be renamed the Chernobyl Central. We've already experienced one of those here - a large layout running Dynatrol (remember that?) that had some spectacular meltdowns back in the day!!
Thoughts?
G8B4Life:
How warm is warm? Unpleasant to touch? I'd expect the LM to get a little warm under load but not so warm it felt hot to touch.
Depending on the smell it could be some component giving up the ghost or possibly (very long shot), depending on what it is, the residue burning off. I have seen some sort of residue of the top of some components of the LM board. It could be some residue from the soldering process or some goop that's deposited deliberately as part of the manufacturing process. I don't know which it is so that's why it's a long shot.
To look for damage there's really only two things to do. First feel the outer casing for deformities and then, if you dare, opening the casing up and looking for damage to the components. You need a good magnifier for that. As the LM is second hand I suspect Ring repairing it won't be an option so you might have nothing to loose by opening it up and checking the board out.
- Tim
William Brillinger:
I'm sure ring would repair it for a small fee.
CPRail:
Here's the latest and greatest:
I put the loco on the track with the RP system on and immediately starting smelling the unhappy electronics smell with some mild heat. No movement, just sitting there with track power on.
Updated the LM-2S to the current standard and uploaded a sound (horn) and assigned it. Could not get the horn to play.
Plugged in a known LM-3S and got the sound to play and loco to move. Notably the sound was quieter than last night using the same module and speaker - this should've been my first warning.
Reinstalled the LM-2S but without speaker for a moment. Nothing smelly, no heat. Plugged in the speaker and within 15-30 seconds the unhappy electronics smell appeared and the module starting getting warm. Waited a moment (45 secs ?) and the module was warmer, to the point where if you held your fingers on the narrow sides for about 15-20 secs you'd start to think about removing them.
Checked the bridge rectifier - it was getting warm as well.
Inadvertently touched the speaker driver and damn near burned my finger!!
This explains the speaker having less volume and the static-y sounding speaker I originally installed. We are getting some serious power leakage through the speaker.
Too bad I killed two $18 speakers to find this out. :(
I wired in the bridge rectifier like I've always done between the red & black wires on the harness, with the KA-4 on the module side. I double-checked that I had the BR the right way round as I screwed that up once - all good.
So, electrical gurus, where's the problem?
William Brillinger:
"So, electrical gurus, where's the problem?"
Open the LM and look it over.
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