Remove Them LEDs - Page 1
Forum section: electronics / beginners

author: bumba000
author_rank: Regular Contributor
timestamp: October 15, 2015, 07:52:22 pm
content: I have a few of these so called lipoly backpacks here for my pro trinkets. I wanted to remove the LED/Diodes from the backpacks, so I did. Now the backpack doesn't charge the battery. So I spent a lot of time studying the schematic and the chip's datasheet yesterday. Then watched Dave's lipo charger video which is what actually helped the most.I wanted to remove the leds and also have a way of using the trinket / arduino to detect when a usb cable is attached. I have the usb detect part figured out. What I'm having some trouble with is why can't I remove the led diodes? What will I have to do to get them out of the circuit but leave the circuit functional?https://learn.adafruit.com/system/assets/assets/000/019/692/original/adafruit_products_schem.png?1410888704http://www.adafruit.com/datasheets/MCP73831.pdfPlease and Thank You, JohnEDIT** I guess I can simply replace them with a shottky??

author: bumba000
author_rank: Regular Contributor
timestamp: October 15, 2015, 09:09:10 pm
content: It seems as though I would like to replace the LEDs with silicone diodes as opposed to shottky diodes. Now I just need to know which size of silicone diodes to use. I have a couple here that are pretty small in size and values but what I'm working on is all surface mount and my silicone diodes are all through hole. So I will need to purchase some new surface mount silicone diodes, but there again I will need to know which value size would be appropriate for the schematic I've linked to above.Thank You, John

author: divelectservices
author_rank: Contributor
timestamp: October 15, 2015, 09:19:05 pm
content: If you just don't want to see them why not just cover them with a small amount of black silicone?

author: mikerj
author_rank: Super Contributor
timestamp: October 15, 2015, 09:26:20 pm
content: The STAT pin on the MCP73831 is an output and doesn't need to be connected. Removing the Charge and Done LEDs should not prevent operation of the charger, so I would re-check the charger CPB to see if you damaged something else whilst removing them.

author: bumba000
author_rank: Regular Contributor
timestamp: October 15, 2015, 09:42:34 pm
content: no. not silicone. thank you though. As for the stat not being required for operation: I can see from the schematic that what you're saying is true and also from what I think I understand from the MCP73831 datasheet. However. Removing the LED seems to make the charging stop. There is a chance though that I've damaged something while removing them. I still have a few left. Maybe I'll try another. I am gently with a very small razor removing the solder until the led comes free. No heat no prying. Just gentle cut strokes. Charge seems to stop. I'll try again...Thank You.

author: sleemanj
author_rank: Super Contributor
timestamp: October 15, 2015, 10:32:56 pm
content: Post a photograph of your board showing your work.

author: bumba000
author_rank: Regular Contributor
timestamp: October 15, 2015, 10:52:45 pm
content: I figured out the problem. I will post a photo in a bit. my cellphone is my camera and it's dead at the moment. (funny I need to charge it too).Ok. The first one that didn't work without LEDs didn't work because I messed it up by shorting it out with a DMM probe the day I got them. The second one didn't work because I had apparently destroyed a trace that is important to the circuit. Under a magnifying glass I was able to see that the trace was blown like a fuse. I know when this happened. It was when I was moving my project from bench to desk and the pwm lead from the arduino struck the ground pin. I recall hearing a tiny pop sound but nothing seemed to have gone wrong. Later on I removed the LEDs and noticed that the battery was no longer charging.Very sorry for the confusion guys and I do appreciate all the input. I did fix the "blown" trace with a short piece of 34AWG mag wire and will post a pic shortly. Since I've been typing (and i'm pretty quick) my batteries gone from 3.56 up to 3.62. Thank you.

author: bumba000
author_rank: Regular Contributor
timestamp: October 16, 2015, 12:20:16 am
content: Here ya go. The green line is where I repaired the trace using mag wire. Not sure why it looks like I added some kind of socket there. I did not. In person with a magnifying glass it looks great. I promise.The green arrows point to where the LEDs used to be and the Red arrow points to the STAT leg of the MCP73831 chip. I have the STAT leg attached to my pro trinket. A couple lines of code and I can see when the usb cable is attached. A bit more code and I'll see if it's charging or maintaining.