Troubleshooting pixels

[drdnva]

I'm trying to troubleshoot a group of firesticks. I had a short at a power injection point. As I'm trying to repair the group I was trying to test new pixels before soldering them in. When using an ohm meter, should there be any connectivity between the V+ and the V- lines on a group of pixels? I have some new totally unconnected pixels that show no connectivity between the +/- lines and some which show a reading of 3.3 ohms. Does the positive ohm reading indicate a short across an IC chip somewhere in the chain? As I tested several of the existing firesticks, some showed no connectivity and some showed the positive reading of around 3 ohms. When those existing firesticks were plugged in to the controller, the lights seemed to light properly and cycle through all the colors properly. However, I'm testing on an extra controller and don't want to plug a string that may have a short back into my main controller running the pixel tree. For extra info, on the strings that show some connectivity, I get the same reading if I check the +/- lines at the first pixel or if the + at the first and the - at the last pixel (7 or 50) in the string.

 

[Skymaster]

Does the positive ohm reading indicate a short across an IC chip somewhere in the chain?

I would say that's a highly likely scenario. The LEDs should show close to open circuit into you hit the switch on voltage for the driver chip, which your multimeter won't be putting out of its probes.

3 ohms at 12V would imply 4A current draw, at idle. 50 pixels shouldn't draw this much at 100%

It does seem odd though that they would work properly.