The .dri Gerber file has that info…
0.2441 3.7913
0.2441 1.5433
1.1624 3.7913
1.1614 0.1358
2.0827 3.7913
2.0827 1.5433
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I have also got bad focers on my delivery for the group buy batch 2.
I just found out now when i soldered the first SMD parts and testing them.
What i have found out so far:
The bad ones all measure 3V or more between POS and NEG and the good ones 2.6V
The make a high pitched noise and the voltage regulation does not work.
Im trying to find out now what is wrong exactly. I’m suspecting the DRV GND pad.
Sucks i have already packed all the focers kits with the IMU soldered and tested 
I’d like to know what you find here. This has been the case for a few people. unfortunately I haven’t personally run into this so i don’t know root cause. I do suspect the quality of soldering of the DRV and surrounding components.
How do you actually measure ant get 2.6V and 3V? Do you power it on? At the moment, I have board that is just with SMT assembly and I still wait for FETs etc. But when I tried diode method I also got roughly 0.6V (between POS and NEG) or so as somebody else here in this group.
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So far i did not find the problem, its not the GND pad.
I also reflowed a DRV chip and it did not change anything.
At least half of the 60pcs is bad. Probably all of one order(30pcs).
With the diode tester
I’m curious about that as well since I get about .51V on all my boards with the diode tester.
Did you change the polarity? Then it should measure 2.6V
I get 0.51V in one direction and no reading in the other direction.
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on my CFOC2 (working) I get 2.57V in one direction and 0.55V in the other.
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Good
NEG - POS + 2.615
NEG + POS - 0.555
BAD
NEG - POS + >3V
NEG + POS - 0.576
It must have something to do with the DRV buck. I resoldered the GND pad on 2 bad focers and it did not help.
I have now unboxed all of the already packed units and so far i got ~25 bad ones
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Oh wow…
Yeah the symptoms of this cause the DRV to not produce a regulated 5V and ends up frying other components. How about resoldering/reflowing the whole DRV?
Did this with one DRV, no change and i also checked the GND pad for solder (it was ok)
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does replacing the DRV on a bad unit with a DRV from a good unit do anything? this could identify the DRV itself as the culprit or determine that it’s something else.
Im going to try this tomorrow. Sadly i dont have any spare drv8301
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I think I may now understand why I’m not getting those readings. It looks like my cheesey meter will only read up to about 1.25V bias. I have a thought and maybe you guys can tell me if it will let the magic smoke out…
I could put my variable power supply across the +/- terminals and slowly increase the voltage until current flows in each direction. I assume that’s what the diode tester is doing(?)
Yes i did this too, i set the regulated power supply to 5.5v and the good focer regulated it down to 5.126V the bad one mad a high pitched noise and did not regulate.
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Great. I’ll try that too. But is it safe for me to do it in both directions?
Also - when you say it regulated it down to 5.126V, I assume you were probing the 5V and GND pins - yes?
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