Atmega 644 and/or 18F14K50 problem

[jman 31]

Like I pointed out yesterday, fixing those cold joints on the IC sockets involves a risk I'd rather not take if I don't have to.

Removing IC's from their sockets is a pretty easy job as long as you do it carefully. If you pry one end up with a small screwdriver then go to the other end and slowly work it up they come out without much difficulty. Plus once you've done a few it gets easier. Then simply touch up the solder joints on the bottom of the board and reinstall the chips. You shouldn't be doing any soldering on the top side of the board.

I agree with Firelord. Seems you have a short somewhere on the board. I typically wash my boards with hand soap, water and a stiff toothbrush. That removes most of the flux and microscopic solder pieces. Make sure it is completely dry before you put power to it though!

[funkystx]

You shouldn't be doing any soldering on the top side of the board.

To clear up a misunderstanding, I've no problem removing the ICs and I'm not doing any soldering on top. But fixing 'cold joints' involves adding solder from the bottom to fill up the holes on top. With the IC sockets installed I can't see how much solder has reached the top side and solder could easily flow to an adjacent pin. If that happens, I need to unsolder that IC socket completely to clean everything. That's a risk and therefore my biggest concern.

Furthermore I already cleaned the PCB with electrical cleaning solvent and a toothbrush to get rid of the flux etc. I even used a magnifying glass to inspect the bottom for possible residue, but that surface is clean.

I'll hook it up to USB tomorrow and feel the components for (over)heating.

[jman 31]

Gotcha! Now I understand what you are talking about! Sorry about the misunderstanding.

[funkystx]

No problem jman!

I just had USB power on the main board for at least 10 minutes, but I didn't notice any increase in temperature on any of the components. Cold as ice!
On this occasion Windows didn't recognized the device either, so I gave it a few more tries on several ports; same result.

So what's next on the elimination list?
Is it the PIC, the Atmega, cold joints, the flu or is it just me?

[r0bbie]

Hi,

Could you post some more hi-res pictures of the solder-side of your pc board?

Regards,

Rob.

[Firelord]

I just had USB power on the main board for at least 10 minutes, but I didn't notice any increase in temperature on any of the components. Cold as ice!

Actually, that is very good. Sometimes a component will die and start to heat up and it is not necessarily directly evident.

Is it the PIC, the Atmega, cold joints, the flu or is it just me?

It actually could be your doubts about the quality of your board. Sorry for being nontechnical, but this regularly happens to me. One day something just doesn't work, the other, when you've already given up on it it starts to work without ever explaining what was wrong. The neat thing is that you rarely get the opportunity to diagnose it in the same state, because it never returns to it. Sometimes you just wish that stuff could talk back to you

[funkystx]

Rob, as requested, here are some hi-res photos from the bottom side:

MD56_Sv3.2-06tn.jpg

MD56_Sv3.2-07tn.jpg

MD56_Sv3.2-08tn.jpg

The little white dusty stuff around the pins are just some cloth remains from cleaning the PCB.
Looking at all those shiny volcanoes from close range, I almost start getting proud of myself!
Just that minor detail that it's not working yet, keeps me from patting myself on the shoulder.

Do you notice anything weird in these pictures?

[r0bbie]

Rob, as requested, here are some hi-res photos from the bottom side:


The little white dusty stuff around the pins are just some cloth remains from cleaning the PCB.
Looking at all those shiny volcanoes from close range, I almost start getting proud of myself!
Just that minor detail that it's not working yet, keeps me from patting myself on the shoulder.

Do you notice anything weird in these pictures?

I agree, this looks à lot better! I see one doubtfull connection but thats is on your inputs connector, so could not be the cause of your current problem.

What is your location in the Netherlands, maybe we are neighbours

Regards,

Rob

[funkystx]

What is your location in the Netherlands, maybe we are neighbours

I currently live in Alphen a/d Rijn. Is that anywhere near you?

[r0bbie]

What is your location in the Netherlands, maybe we are neighbours

I currently live in Alphen a/d Rijn. Is that anywhere near you?

I'm living in Oud-Beijerland, if you are willing to spend one hour in the car, your welcome

Regards,
Rob.