Monochron working ... for a while
Moderators: adafruit_support_bill, adafruit

Monochron working ... for a while

by arclight on Thu Oct 04, 2012 5:28 pm

I seem to be having issues with a Monochron similar to some previously posted. It passes the initial power supply and no-display "beep" tests. The clock boots, can be set, runs for a while (minutes to overnight), then the display freezes/freaks out. I can reset it by pulling and replacing the power. Alarm & 12/24hr settings are preserved on restart, time and date are not (implying an RTC issue?). Testing the coin cell gives 3.3V so I can rule that out. I'm tempted to wipe down the board to remove flux & remelt joints near the RTC.

If need be, I'll post better photos later; the phone camera seems to want to make everything smudgy and washed-out.

Monochron - front
monochron_front.png (409.19 KiB) Viewed 806 times

Yes, C2 should be lying flat. Also, that's a replacement LED for similar reasons. :/

Just noticed R10 is missing (confessional debugging); will investigate the significance of that ASAP.

Monochron - back
monochron_back.png (388.65 KiB) Viewed 806 times

Thanks much,

-- Bob

PS: This is not my week; software issues drove me to hardware. I expect the clock problems to be minor setbacks, though it's part of a long string of failure. Most upsetting was the build process for the IoT Printer kit, but that's a subject for another post (short answer: soldering wire to header pins is a hack, a particularly miserable and frustrating one to spring on someone building a kit. Zero fun.)
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Re: Monochron working ... for a while

by adafruit_support_bill on Thu Oct 04, 2012 6:19 pm

Hi Bob,

R10 is not used, so don't worry about that. Can't really see much detail in the soldering. If you can get some better photos, that would help. A little larger would be good too. About 800x600 should be fine.

I have heard of crystal oscillators misbehaving due to residual carbonized solder flux, but yours doesn't look all that bad from what I can see from here.

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Re: Monochron working ... for a while

by at2marty on Mon Oct 08, 2012 11:03 am

I know this is off topic, but I'm curious... In the first picture I noticed that there is an R2' and an R2, the same with IC2' and IC2. What is the difference and why are they labeled that way?
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Re: Monochron working ... for a while

by Wody on Mon Oct 08, 2012 11:38 am

at2marty wrote:What is the difference and why are they labeled that way?

The answers are in the instructions, at
Just search for IC2 and R2
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