My Atmega 644 problem

Discussions related to MegaDrum Hardware

Re: My Atmega 644 problem

Postby dschrammie » Fri Dec 10, 2010 4:24 pm

Firelord wrote:Could any of you post a photo of your PCBs? If you don't want to post it to the main forums you may PM me. Practice has shown that photos usually allow to at least evaluate the probability of a hardware related problem due to soldering/assembly.


Yep, I will post mine. I just got back into town from a business trip, so I will try to take some time tonight after work to pull the board out of the chassis and snap some photos. Thank you very much for taking an interest in our "problem" and offering assistance.

Kimouette, we should definitely keep each other posted on our progress!
dschrammie
 
Posts: 96
Joined: Wed Jul 07, 2010 3:46 pm

Re: My Atmega 644 problem

Postby kimouette » Fri Dec 10, 2010 5:27 pm

Firelord wrote:Could any of you post a photo of your PCBs? If you don't want to post it to the main forums you may PM me. Practice has shown that photos usually allow to at least evaluate the probability of a hardware related problem due to soldering/assembly.
In my case that wouldn't be usefull since I dont have a good camera :(
kimouette
 
Posts: 265
Joined: Fri Jun 27, 2008 5:19 am

Re: My Atmega 644 problem

Postby dschrammie » Sat Dec 11, 2010 7:34 am

Okay, this is the first time I've actually pulled the board out...so first time I'm seeing any of this.

Image

Image

Image

Image

Image

I haven't had a chance to look at any of the specifics that Dmitri mentioned, but there definitely appear to be some "questionable" soldering joints...and some blobs that I can't quite tell if they were intentional or not. I do have some close ups if you want to see them, but the macro function on the camera was being kinda weird and giving me a weird shadow.
dschrammie
 
Posts: 96
Joined: Wed Jul 07, 2010 3:46 pm

Re: My Atmega 644 problem

Postby Firelord » Sat Dec 11, 2010 9:11 am

Well, the overall assembly looks good. However, there are some "questionable joints" indeed, as an example:
71186-m-0_badjoints.jpg

In this case though the most important joints are located close to ATmega and PIC, so you could try and resolder them. An excellent video on soldering is available here, should you need it: http://www.youtube.com/watch?v=I_NU2ruzyc4
You do not have the required permissions to view the files attached to this post.
Firelord
 
Posts: 666
Joined: Wed Jun 10, 2009 7:50 pm
Location: Estonia

Re: My Atmega 644 problem

Postby jman 31 » Sat Dec 11, 2010 2:04 pm

There is nothing wrong with the solder joints. I know because I soldered it and it worked for over a year. More likely one of the joints or traces have been weakened by taking the IC in and out. I had it out several time when I had it so that is a very good possibility. The traces that you pointed out firelord were where I cut between the traces to make sure there was no shorts on the board. I used the iron style transfer back then and sometimes the traces tend to melt together. The blobs you see is just some places where some solder got on the ground plane.

dschrammie, I would be glad to look it over for you if you want to send it to me. I will pay to ship it back.

By the way, did you try replacing the old chip to see if it would work again?
jman 31
 
Posts: 536
Joined: Thu Jul 10, 2008 10:51 pm
Location: USA

Re: My Atmega 644 problem

Postby kimouette » Sat Dec 11, 2010 2:52 pm

I've just added few pictures of my board here :
http://picasaweb.google.com/Kim.Tanguay ... drumBoard#

I,m sure it's pretty useless since the iphone.... well, it's a phone not a camera!
The solderings are all shinny in reality, but it looks bad on the pictures!

In Picasa you can use the magnifying glass tool to zoom-in, but you'll only see more blurs and more pixels!
kimouette
 
Posts: 265
Joined: Fri Jun 27, 2008 5:19 am

Re: My Atmega 644 problem

Postby Firelord » Sat Dec 11, 2010 4:31 pm

jman 31, I didn't realize that it was your production.

kimouette, the board looks good. There are some joints here and there that I would resolder, but no evident defects.

I am sorry, but there is nothing else I can say at this point. The problem you have is not trivial and probably requires you to have your board examined by a professional.

Unless, of course, the ATmega chip has defects by itself.
Firelord
 
Posts: 666
Joined: Wed Jun 10, 2009 7:50 pm
Location: Estonia

Re: My Atmega 644 problem

Postby dschrammie » Sat Dec 11, 2010 10:54 pm

Hey Jeremy - please know that I was definitely not intending to indicate or suggest that you did anything wrong or poorly...no offense was meant at all. There are a few soldering points that I simply don't know if they make a difference or not. Here are some of the close-ups (please forgive the weird shadows):

Atmega soldering points:
Image

Image

At the PIC:
Image

I was thinking I'd probably have to take the multimeter to each connection and check for 1) solid connections, and 2) potential shorts. There are a few places where it looks like there were "lines" of solder added to the PCB where maybe the line wasn't conducting just right. Figured I'd check to make sure there are no shorts in those locations either.

If I can't find anything then I may very well take you up on your offer to look over it Jeremy...but by no means would I ask you to pay to ship it back.

I have not put the old chip back in, mostly because it's a pain in the butt. I also don't know what I would be checking for by putting the old chip back in - to see if it worked? I'd assume that if a joint got loosend here or there then the unit wouldn't power up at all (which it does...it's just not uploading the firmware).
dschrammie
 
Posts: 96
Joined: Wed Jul 07, 2010 3:46 pm

Re: My Atmega 644 problem

Postby jman 31 » Sun Dec 12, 2010 1:22 am

Hey Jeremy - please know that I was definitely not intending to indicate or suggest that you did anything wrong or poorly...no offense was meant at all. There are a few soldering points that I simply don't know if they make a difference or not.


Hey man, no problem I wasn't trying to make it sound like I was trying to point fingers in another direction! I was just making a point that I didn't think it was a hardware issue. The soldering may have become weak over time from the chip being changed, I don't deny that. However, I think that it is pretty solid because I have had the chip in and out several times with no ill effects. I definitely don't want to have sold you a faulty unit though!!! It very well may be a hardware issue, but it doesn't sound like one to me. I did bridge some bad traces with solder that may have weakened with the chip changes. I think a good test would be to try your old chip and see if it misbehaves. It is very simple to change out with the help of a small flat head screw driver. Pull one end up and then work the other end slowly out. I uploaded new FW to it just before I sent it too you with no problems at all, but I didn't do it the same way that you are trying so that may be an issue.
jman 31
 
Posts: 536
Joined: Thu Jul 10, 2008 10:51 pm
Location: USA

Re: My Atmega 644 problem

Postby Firelord » Sun Dec 12, 2010 10:16 am

Actually I'm beginning to suspect this issue is not related to the boards, but to ATmega. I understand that Dmitri tests all chips prior to shipping them... for all I know it could indeed be the issue Dmitri had with his test board. But two people with the same issue on two different boards, what are the odds?
Firelord
 
Posts: 666
Joined: Wed Jun 10, 2009 7:50 pm
Location: Estonia

PreviousNext

Return to MegaDrum Hardware

Who is online

Users browsing this forum: Bing [Bot], Google [Bot] and 71 guests