RailPro > RailPro Specific Help & Discussion
Bad-ish LM-2S?
G8B4Life:
I'm not sure of how you could test this, I'm no electronics guru but from the sounds of it one or both (there is two on the board I believe) of the audio amplifier IC's is damaged (shorted open, you should not get any power out to the speakers unless you press a button). No heat and smell when nothing is connected to the speaker connections supports this. As you noted the speakers are probably damaged now as well and I wouldn't use them until you can confirm their impedance is still good.
The rest of the LM may be fine as you can connect to it and update it etc or are there other issues besides what's going on with the audio side fault?
- Tim
Alan:
Speaker voice coil is shorted.
CPRail:
The LM works fine, just no noise and cooking speakers. As Alan mentioned, it's shorting across the speaker voice coil.
I need a module to drive my turntable motor. No sound needed there. Can I use this LM for this application?
Alan:
--- Quote from: CPRail on December 29, 2020, 09:38:37 AM ---The LM works fine, just no noise and cooking speakers. As Alan mentioned, it's shorting across the speaker voice coil.
I need a module to drive my turntable motor. No sound needed there. Can I use this LM for this application?
--- End quote ---
As long as your turntable motor draws less current than the drive output of a LM, then sure. Assuming your turntable rotates reasonably free then I doubt its motor will exceed LM capability.
G8B4Life:
--- Quote from: CPRail on December 29, 2020, 09:38:37 AM ---I need a module to drive my turntable motor. No sound needed there. Can I use this LM for this application?
--- End quote ---
Yep, sure can. Just load the accessory program to it and then you can download the turntable project to it (project may need to be modified a little).
Backing up a little, You noted that you've damaged two speakers now. Were they both wired up to the LM at the same time? I'm wondering if the audio amplifiers on the LM were damaged when you got it causing it to damage the speakers or if the speakers you used were to blame (ie, they were only 4 ohm and if you wired them both in (in parallel) you only got 2 ohm load) which damaged the LM.
Edit: Alan got in before I did and makes a good point on the current draw of the turntable motor. If the turntable motor draws more current than the LM can handle you can always use the LM to drive something like a power transistor so the transistor supplies the power to the turntable. How you get the motor to go forwards and reverse in this case is not something I can think of at this time of night (I need to sleep on it), our old transistor DC throttles used to use a toggle switch after the transistor for that part but that's not what you want in this case.
- Tim
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