Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Reverse engineering the LED bar
#1
I'm working on an add-on hardware board for the Da Vinci Duo 2.0A to make it easy to flip to Arduino/RAMPS without any wire / connector changes or changes to the Da Vinci hardware (so you can easily go back to the original board). I have most of this working, and am looking at the LED bar now. While I believe I now understand how it works, I think in the process I likely fried the surface mount transistor.

Attached is a picture of the part - it's labeled as a WIP 47 SMD transistor. Cross referencing the 47 part doesn't find an appropriate transistor with correct package. It does identify something fairly appropriate in the BAS40 series (which is a schottky power transistor, which makes sense for this application) but the 47 cross references into a different packaging/pinout (the BAS40-07). So I don't think I've been able to identify the transistor correctly.

Wondering if anybody else might know more than I about this? I'm not familiar with surface mount devices, so it's virgin territory for me! If I can identify the device, then I could do better testing and verify if I have the correct signals and if it is working or if I need to replace it. Close up picture of the transistor attached.

For those interested, I believe the top pin on the connector is ground, the middle pin is a logic level signal for PWM (to vary brightness) and the bottom pin is 12VDC. In my case, if I add 12VDC to the single pin side of the transistor, the LEDs light up just fine. But I've not found a way to get the transistor to switch when adjusting the middle pin (which is what it connects to). I think it may be because I screwed up and gave it 12V - and if it is indeed a logic level instead of 12V (3.3V or 5V) then likely I toasted the puppy.

Anybody have a working LED bar to sell? I'd like to continue to try to reverse engineer the bar and if I can't identify and replace the bad transistor (assuming I'm correct that it is dead) then a new unit would help to try to figure this all out.[Image: ledtransistor_2016-01-04.JPG]
Reply
#2
You still need this? I've got a working light bar from a 1.0 that appears to have the exact same layout as your picture. I assume they are the same. Let me know.
Reply
#3
'w1p' also corresponds to a SOT23 BFT92 PNP transistor from NXT.  It's a 5Ghz wideband, so I'm not sure that would be used to drive LEDs.  Maybe XYZ found a reel cheap...


http://www.s-manuals.com/smd/w1
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)