Orientation of Q4 (Photoresistor) on v1.2.0 - JLCPCB is asking

[tispokes]

Hi, got this mail from JLCPCB:

Sorry to bother you, but there is one thing that we want to confirm with you about your SMT order before proceeding.



Since we are not so sure about the polarities of the components Q4 are correct or not.
Could you please kindly check if the polarities and placements of the components are correct in the below picture?
Is it okay to proceed with production?

I used the latest parasite.csv as BOM and parasite-top-pos.csv for positioning.
As I'm not so good in reading schematics, I Prefer to ask.

My opinion: It's wrong.
The Emitter (PHOTO_OUT) has to be connected to Pin 7 and not 8. For the collector the same just vis-à-vis.

@rbaron is the pos csv maybe wrong here?

[rbaron]

tl;dr: Q4's collector goes on the left. The original position is correct and JLC's suggestion is not.

Often engineers from JLCPCB will suggest this change (see #3). I just made two changes to help with this confusion:

1. Made the footprint dot for Q4 (which represents the collector, sometimes annotated with a +, with a | or with a C by JLC ) more visible (it's partially cropped in JLCPCB's render)
2. Added instructions about Q4's orientation in the How to order Wiki page.

Hopefully this helps.

[1technophile]

Note that with the files from cc8dcf9, the photodiode is per default oriented in what seems to be the wrong direction, when importing the file with JLCPCB. Before any JLCPCB engineer checks.

[rbaron]

Thanks @1technophile. I have a feeling the base internal orientation unfortunately changes at JLCPBC from time to time, whenever they update the component model. It was correct when I first set it up and also in the original comment above. If somebody has a better explanation, please let us know.

Please always double check the orientation with the wiki whenever placing a new order. There you can see the orientation unambiguously, independent of the internal, supposedly unstable representation JLCPCB uses.