uO_c 8hp ornament and crime.

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funketek
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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
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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..

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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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charonme
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Re:

Post by charonme » Thu Mar 12, 2020 1:50 pm

charonme wrote:
Sun Apr 14, 2019 4:08 am
Will I have problems with the power issue that the "power supervisor" is supposed to solve on the other pcb version?
well turns out I do have a startup problem, so I'll probably try to hack the supervisor into the old pcb version somehow if I can figure it out or find a guide

hmm it still seems to be missing from the BOM, nor can I find any information about the specific model anywhere, except the jakplugg schematic that says "MIC803"
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Altitude909
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Thu Mar 12, 2020 6:25 pm

Youre probably looking at the old BOM


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Altitude909
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Thu Mar 12, 2020 6:26 pm

^
Noice. Embedded sheets

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col
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Re: uO_c 8hp ornament and crime.

Post by col » Thu Mar 12, 2020 7:10 pm

Altitude909 wrote:
Thu Mar 12, 2020 6:26 pm
^
Noice. Embedded sheets
wow yeah, impressed!

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charonme
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Re: uO_c 8hp ornament and crime.

Post by charonme » Fri Mar 13, 2020 2:06 pm

Altitude909 wrote:
Thu Mar 12, 2020 6:25 pm
Youre probably looking at the old BOM
interesting, thanks! well the old bom is still linked from the main page https://github.com/jakplugg/uO_c
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Altitude909
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Fri Mar 13, 2020 4:16 pm

yeah. i'll let him know

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charonme
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Re: uO_c 8hp ornament and crime.

Post by charonme » Sat Mar 14, 2020 6:12 am

turns out that recommended supervisor is no longer manufactured, so I'm looking at some replacements and wonder: how was the original one picked? what should be the threshold voltage and the delay? I hoped I'll find out if I look at what happens when the teensy fails to boot properly, but it seems there is not much difference:
Image

so maybe it's enough to delay the startup just a couple of ms after the 5V regulator output exceeds ~4.6V or so? The original implementation waits 1.12s after the Teensy's 3.3V regulator exceeds 2.63V

this is with a different PSU:
Image

(btw the teensy 3.3v regulator seems to output slightly more than 3.3v)
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Altitude909
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Sat Mar 14, 2020 7:30 am

charonme wrote:
Sat Mar 14, 2020 6:12 am
turns out that recommended supervisor is no longer manufactured, .
Nope, still active:

https://www.microchip.com/wwwproducts/en/MIC803

https://www.mouser.com/ProductDetail/Mi ... NVmA%3D%3D

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charonme
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Re: uO_c 8hp ornament and crime.

Post by charonme » Sat Mar 14, 2020 7:49 am

ah, right it's the Micrel brand that is no longer manufactured. Anyway all my questions still stand: how were the values picked and what could be a safe replacement
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Sat Mar 14, 2020 8:08 am

its the 4.3v version

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Re: uO_c 8hp ornament and crime.

Post by proonjooce » Wed Apr 08, 2020 4:12 am

interested in building this but seeing a bit of conflicting/confusing info about screens, some that fit, some that don't etc.
does anyone have a link to a screen to purchase (preferably in UK or EU) that they can confirm works with the uo_c? preferably one that comes with it's own PCB already. seems like a bit of a tricky part to get right so would be great if i was 100% sure i at least had the right part first!
also, is the embedded BOM above the most up to date version?
thanks :)

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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Wed Apr 08, 2020 5:59 am

This:

www.amazon.com/HiLetgo-128x64-SSH1106-D ... 352&sr=8-3

That seems to be the "standard" now. The Adafruit style ones are gone. The boards have oval holes to fit either style

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Re: uO_c 8hp ornament and crime.

Post by Overand » Tue Apr 28, 2020 8:54 am

I tried to find an answer elsewhere on this, so sorry if I missed it!

The PCB label & instructions specify “either way” for the power connector. But, the specs list power cosumption as 95mA +12, 0mA -12 (if I recall). It seems like these things are mutually exclusive - either the board draws 85mA from “whichever power supply leg it happens to be connected to,” or it would draw ~43mA from each, right?

So, which side of the PCB/power connector has the actual power draw?
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Altitude909
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Re: uO_c 8hp ornament and crime.

Post by Altitude909 » Tue Apr 28, 2020 9:04 am

Overand wrote:
Tue Apr 28, 2020 8:54 am
I tried to find an answer elsewhere on this, so sorry if I missed it!

The PCB label & instructions specify “either way” for the power connector. But, the specs list power cosumption as 95mA +12, 0mA -12 (if I recall). It seems like these things are mutually exclusive - either the board draws 85mA from “whichever power supply leg it happens to be connected to,” or it would draw ~43mA from each, right?

So, which side of the PCB/power connector has the actual power draw?
no. There is a bridge rectifier in the power circuit so the + always routes to the + and - to -. Current draw on each rail isnt related to that

artparks
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Re: uO_c 8hp ornament and crime.

Post by artparks » Tue Apr 28, 2020 2:42 pm

does that mean the orientation of the rectifier doesn't matter? the rectifier i have has no notch or other orientation marking, and i'm unsure if that matters. it has + and - labelled pins on one side.

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Re: uO_c 8hp ornament and crime.

Post by PabloSrNaranja » Tue Apr 28, 2020 4:47 pm

Hi everybody. I had just finished my uO-C from pusherman.

It seems to work ok, except that the outputs does not work. The four of them are stuck at 11,1V.

¿Can anyone help me out? Thanks!!

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Re: uO_c 8hp ornament and crime.

Post by Neutron7 » Tue Apr 28, 2020 9:15 pm

since it is common to all the outputs, It is something common to both output op amps. either power (check op amp pins 4 and 8 for -+12v) or something to do with the voltage reference. that 2.5v is supplied by pin 3 of the DAC, and can be measured at the bottom of c19. after that it is divided to 1.25v by r13 and r14, you can measure between the 2 of them for that voltage.

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Re: uO_c 8hp ornament and crime.

Post by Neutron7 » Tue Apr 28, 2020 9:44 pm

artparks wrote:
Tue Apr 28, 2020 2:42 pm
does that mean the orientation of the rectifier doesn't matter? the rectifier i have has no notch or other orientation marking, and i'm unsure if that matters. it has + and - labelled pins on one side.
the + is pin 1 so imagine the stripe is along the edge with + and -

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Re: uO_c 8hp ornament and crime.

Post by artparks » Wed Apr 29, 2020 3:02 am

Neutron7 wrote:
Tue Apr 28, 2020 9:44 pm
artparks wrote:
Tue Apr 28, 2020 2:42 pm
does that mean the orientation of the rectifier doesn't matter? the rectifier i have has no notch or other orientation marking, and i'm unsure if that matters. it has + and - labelled pins on one side.
the + is pin 1 so imagine the stripe is along the edge with + and -
Fantastic, thank you.

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Re: uO_c 8hp ornament and crime.

Post by PabloSrNaranja » Fri May 08, 2020 7:11 am

Neutron7 wrote:
Tue Apr 28, 2020 9:15 pm
since it is common to all the outputs, It is something common to both output op amps. either power (check op amp pins 4 and 8 for -+12v) or something to do with the voltage reference. that 2.5v is supplied by pin 3 of the DAC, and can be measured at the bottom of c19. after that it is divided to 1.25v by r13 and r14, you can measure between the 2 of them for that voltage.
Hi,thanks for the advice. I still measuring strange voltages.
I will ilustrate with some photos so probably you can figure out.
I can do whathever measures is needed.

Apreciate it! ;)
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Neutron7
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Re: uO_c 8hp ornament and crime.

Post by Neutron7 » Fri May 08, 2020 7:29 am

2DCFF605-0FC0-4050-82C3-7982AB9C6F32.jpeg
4.4v on the negative rail is not good!

can you check right on the - pin of the rectifier? (it looks like that pin could use a reflow as well)
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