I am taking over a project that was using a circuit with a BPR-301 sensor.

I needed to swap for a smaller sensor so I chose OPB733TR sensor

old original: https://www.americanbrightled.com/pdffiles/ir-uv/ir/BPR-301.pdf

New smaller sensor:
https://www.ttelectronics.com/TTElectronics/media/ProductFiles/Datasheet/OPB733.pdf

I used magnet wire from sensor PCB to the original PCB. The resistance is about 1 ohm. The sensor circuit does not seem to operate at all. I test with original and it works fine. I confirmed resistance and continuity from end to end.

I’m wondering if the magnetic wire having 1 ohm of resistance is too much for this style sensor? I confirmed wiring is the same for both style sensors.

any help appreciated!!

 

The wiring is NOT the same. Check the datasheets.

 

I underatand. It was wired as follows

old->new
Pin 4->1
Pin 1->2
Pin 2->3
Pin 3->4

so it is wired to the main PCB the same from old sensor to new

 

Is there any chance resistance is too high? Or is there anything else different in the specs that would keep it from working on the same PCB?

 

If you can post a schematic diagram of the circuit on the PCB, it may give us some more clues.

 

I got 1 of the 2 sensors working. I had an adapter flipped.

Here is the new sensor schematic:


And the old sensor schematic:


I was able to get U1 to work on the new PCB, but U2 just does not seem to work.

1. I tried the old sensor and confirmed the connector on the PCB is working
2. I checked wiring end-to-end from edge connector to the pins on the new sensors.

Everything is wired identically. There are no shorts or connection issues and I have triple checked everything. The only thing I can imagine is that wiring 2 sensors together with the OPB733TR is different then how it was for the BPR-301 for some reason. I am not an electrical engineer and am not too familar with the symbols. I noticed the arrows are not shown on the Emitter/Collector:



Could this have something to do with U2 not working correctly in the configuration?

This is the edge connector the E1-E4 connects to on the main PCB:

 

Certainly with optical sensors polarity is important for both the LED and the photo-transistor. And unfortunately magnet wire all looks the same , so it is difficult to keep track of.