Alpha clock 5 problem: dead

#ifdef moose

I recently built an Alpha Clock Five. It was working fine. I brought it to work today, to show it to some of the other geeks. When I got home, I went to plug it in, and it didn't work. There was a small flash (arc?) from the a/c outlet as I plugged in the power supply, but the power supply is working. I measured its output at 9.2V at the jack. I also checked the Reg 5V point on the PCB, and it shows 4.92V, so it's got power, and the regulator is working. 

What should I check next?

Thanks for the help,

David

Windell Oskay

Yup, that sounds like a problem, and not one that we've seen before.  

So, there are two basic possibilities.  Either the microcontroller is running, or it isn't. 

If it is not running, that could be due to not being seated properly in its socket, or a bad solder connection at one of several critical points such as the crystal oscillator.   Gently take off the LED digits and look at the bottom of the circuit board to see if you can see any signs of what might have gone wrong. 

If it is running, then it is possible that through static discharge (or something similar) the LED driver chips were damaged, and are no longer producing lit LED segments. 

Now, how to tell the difference?  The alarm and rear-panel "nightlight" LED are independent of the LED segments, and should respond normally if the microcontroller is actually running-- although it may be hard to navigate to the right menu places to test those.  If you have a USB-TTL interface, you could also try reprogramming the clock (or simply communicating with it via serial) to see if it's up and running.   (You could also try reflashing the bootloader, if you happen to have an AVR ISP programmer handy.)

If all else fails, you might consider sending it back to us for analysis and/or repair-- again, this is not something that we've come across before (unless it does turn out to be a bad connection, as it usually does).

#ifdef moose

Thanks for the fast response. 

The real panel LED is dead as well, so I guess that means the MCU isn't running. Could something have been bricked by the arc when I plugged in the power supply?

All the ICs look like they're well seated (but I did have a problem with the U3 chip; the dot segments didn't work until after I reinstalled it). I'll try reinstalling the MCU.  I don't see any obviously bad solder joints, but I'll take a closer look as soon as I find my magnifying glass, and I'll let you know if I find anything.

I was planning to get an FTDI cable to play with the software, but I don't have it yet, nor do I have an ISP. I do have a multimeter, if there's anything else I can check.

Thanks,

David

. 

Windell Oskay

The arc itself probably isn't harmful-- the power supply seems to have survived --but it's possible that there was an electrostatic discharge at the same time, or that the power supply let through a voltage spike.  The crystal or the memory of the chip could have possibly been damaged, although (and if so) that's not really something that we've seen before in this kind of context.

The best option might be to try swapping in a good chip, to see if that helps.  If the MCU is not running at all, then it probably can't be programmed through the FTDI cable.

#ifdef moose

I pulled all the ICs and reinstalled them. I removed the display modules and inspected the solder joints and I can't find anything obviously bad There were no bridges that I could find (but I wasn't expecting any, since it did work for a few days). Some of the joints looked a little dull when viewed from above, but they're shiny when viewed from the side, and none of the components feel loose.

The rear LED didn't light when I connect the power supply (I didn't reinstall the displays). I tried moving through the menu blind, making a few changes at each stop, to see if it would make noise or light the LED.

I'm stuck. If you're willing to try to diagnose the problem, how should I prepare it for shipment? I assume you want the PCB and the ICs. Should I remove the ICs and put them on the antistatic foam, or leave them installed, and should I put everything back together, and replace the LED modules?

Thanks,

David

#ifdef moose

Sorry, I didn't see your last response before I wrote the above. If I order a new ATmega644 MCU, will you flash it with the alpha clock firmware? I was planning to order an FTDI Friend (or a cable; I see you're out of stock on the Friend) as well, but not an AVR ISP, unless you'd suggest the ISP. As you can tell, this AVR stuff is all new to me, although I have plenty of professional programming experience.

Windell Oskay

Hi David,

Please contact us directly at the store by e-mail to arrange for a replacement chip or return shipping.

-Windell

albertel

Hrrm, So mine has also died (I'm the one that made the bike turn signal variant) I had shelved it in a working condition ~ 4 months ago and wanted to get it remounted this weekend.

Plugged it in, LEDs lit up some. Unplugged it, reconnected a wire I had solder to the Time/Settings button, went to reprogram it and got 'programmer is not responding' and now I don't even see any LEDs light up.

I've got no problem buying replacement parts I'm just not sure where to start to make sure I'm getting the right thing? Should I just assume I some how fried the atmega?

Windell Oskay

I am not sure exactly what the problem is, but it doesn't sound like a chip kind of problem.  If some LEDs were lighting up initially, it's almost certain that it is not-- it's much more likely a power supply type of problem or an already weak connection somewhere that was coming loose.   Do you have an alternate power supply that you can test? And, you might want to open up the case and look carefully through the PCB to find any possible loose or cracked solder connections that might be at fault.  If you really get stuck, you might also consider sending it to us for diagnosis; we're pretty quick at finding problems like these.