uO_c 8hp ornament and crime.

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funketek
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Joined: Sun Jan 19, 2020 11:48 pm

Re: uO_c 8hp ornament and crime.

Post by funketek » Thu Feb 13, 2020 3:48 pm

Hi friends - I am new to DIY, have about 5 or 6 modules successfully built including a couple of SMD boards, but this one is giving me problems. I was hoping someone with more experience than me could confirm I am on the right track:

So I tried building the uOC and upon powering up, got a smoking resistor at R60 (4.7ohm). I turned it off quickly and started continuity testing for any solder bridges. While I do get some hits on U5 and U10 (pins 3,4,5 for each) since these are all grounds I assume those are OK? Same situation with U2, but the continuity hits all correspond with the ground pins.

However on IC6 (over the heat sink) I am registering continuity between the large flat pin (pin 1?) and pin 3(top right). On U7 I am registering continuity on pins 1,2 and 3 (all three across the top). Looking at the schematic, I would expect it between 1 and 3, but not 1&2 or 2&3. Pins 1 &3 also register continuity with the ground pins on the power jack (as does pin 3 on IC6). Is it safe to say these are the likely culprits?

I plan to reflow these two components and hopefully fix the issue, but is there anything else I should be testing? Lastly, if I am still getting 4.7 ohms of resistance from the now slightly crispy R60 is it OK to leave it or should I replace it. For the 5 cents it costs the answer is replace it probably, but since I only bought one I was curious if it would hold up in the short term while I try and troubleshoot. I would sincerely appreciate any advice.

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Altitude909
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Thu Feb 13, 2020 5:12 pm

youre shorting the power to ground somewhere, you need to find that first. Look at the file and check around all the 3.3V traces to the ICs

funketek
Learning to Wiggle
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Joined: Sun Jan 19, 2020 11:48 pm

Re: uO_c 8hp ornament and crime.

Post by funketek » Thu Feb 13, 2020 11:18 pm

I really appreciate the guidance. I did check all of the 3v3 pins and capacitors. I noticed C3 and C8 around the around U7 were hitting ground on both sides of the capacitor. I reflowed those as well as the U7 and IC6 and no more continuity where I wasn't expecting it! I just plugged it back in and no smoking resistor either! Going to check voltages tonight or tomorrow to see how it's looking..

funketek
Learning to Wiggle
Posts: 5
Joined: Sun Jan 19, 2020 11:48 pm

Re: uO_c 8hp ornament and crime.

Post by funketek » Tue Feb 18, 2020 10:31 am

Final update - all reference voltages checked out so I installed the Teensy and was able to program it. uOC still did not fire up despite hitting the "reboot" button on the Teensyduino GUI. Don't know if this had anything to do with it, but clicked the menu drop down and selected reboot instead of the reboot GUI button and the uOC came to life!

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