I have purchased several WiFi Kit 8 and WifFi Kit 32 boards. I like the design and the build quality.
However, in two cases, one on a kit 32 and one on a kit 8, I have had the schokkty diode D1 (1N5819) fail open. This has occurred under loads of less than 100 ma and no shorts. Fortunately, I have had spares in my parts box and they are easily replaced. Has anyone else had this experience? I am beginning to suspect that these diodes came from a bad lot.
Doide D1 Failure on Kit 8 and Kit 32 boards
The first use was broken?
Can you provide some pictures?
No, the diode did not fail on the first application of power. Since the devices run fine off USB power even if the diode is blown, it was not obvious right away that there was a problem. I would estimate that both diodes blew open within the first 8 hours of battery operation. In other words, they failed within a few hours of carrying forward current.
I used MBR120 diodes as replacements since I had five of them. Well, three now!
I am not sure what good pictures will do. I did not save the bad diodes and both boards with the replacement diodes may be in service so I can not be sure if this is a pictures of a repaired board or a stock board. I lost track of which is which. Here’s a picture. The schokkty diode is in the top right. I don’t know that there is much you can do about this, since the boards are not lot controlled and there is no serial number.
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Sorry, we don’t know what is causing the problem now. The purpose of this diode is to prevent the +5V voltage from coming directly to the battery. We have hardly encountered this diode damage.
What is the USB voltage or battery voltage?
USB voltage is 5 volts and battery voltage is 3.3 volts.