[CLock3]

Well, I just finished my first CMoy build, and unfortunately, it sucks. I'm not sure what went wrong, but only certain frequencies come out of the left ear, and the right ear is completely distorted. I thought everything was going so well, too. I'm so discouraged, haha. I spent all the cash on the parts and now I have a pile of useless crap and solder. I think part of the problem is solder bridges, which I tried to avoid, but it's so hard working in such a small area with so many things, and now I don't know if there's much I can do to remove them. So, I'm not sure if anyone has any ideas or anything, but I was kind of wondering if anyone on here would be able to take the stuff I have now and fix it for me? I hate to have the money go to waste by not having an amp to show for it, and I'd like to have one anyways. I hoped for the satisfaction of building one myself, and figured I could do it as I have some experience with electronics and soldering, but i'm not sure if I can recover this one, haha. Let me know what you all think. Thanks in advance for any help.

 

[Pars]

Post pics of the top and bottom of the board and we'll help you fix it...

 

[breakfastchef]

Where did you get your CMoy building information? Did you follow an online guide or buy a kit?

A solder sucker/pump and some desoldering braid from Radio Shack are great for removing solder, solder bridges and components.

 

[CLock3]

I used the tutorial on tangentsoft, and followed it specifically. Also, I'll get some pics of it tomorrow and post them. Thanks.

 

[CLock3]

Alright, got some pictures today. I'm not sure how well you'll be able to tell what's going on really, but any advice would be great. And the bottom has a bunch of solder bridges on it right now. I tried heating some of it up and then getting it with the solder sucker, but I can't get the thing close enough to the solder, so I don't know what to do. The bottom is a complete mess now. It's pretty frustrating, haha. Anyways, here's the pics. Thanks again for any help.
Click the thumbnails for the full version:




Maybe my best bet it to take the other half of the protoboard and try building it again?

 

[fortney]

You need to get some desoldering braid. It will be easier for you to use than the sucker. Spread the braid open a bit before applying it to the solder area and it will work better.

A spade tipped constant temperature soldering iron is best, but use what you have. You should to apply high heat briefly when soldering or desoldering so reposition everything if the braid is not drawing up the solder after a second or two.

After the unit operates well then trim the component leads.

Breathe while working on it; you will enjoy it much more.


Even one solder bridge will cause the unit not to function so perhaps you already know what is wrong with the circuit.

F

 

[Pars]

Clip the leads as close to flush with the board (bottom side) as you can. Yu have bridging between many of the opamp pins (see attached markup). Also, clean up the circled area around the V+ & V- input and the virtual ground (the two traces down the middle of the board).

EDIT: Also, you need to pay attention to the polarity on the large caps... one of them is backwards.

 

[xmokshax]

the best advice i can give you if you need to reflow and/or desolder joints is to get some flux paste. this is readily available at rat shack (here's a direct link), and although i haven't used their flux paste, i would imagine it'll work fine. all you need to do is apply a small amount of paste to the joint you want to reflow, then apply your iron (+ desolder braid) or solder sucker to the joint to get rid of the excess. you'll find that adding a bit of flux works like magic for getting a joint flowing freely again.

no need to despair - you should be able to fix up your cmoy without too much trouble. clean up those bridges, switch the polarity of the one capacitor, and you should be well on your way to a working amp. i'm not sure how likely it is that the reversed polarity and solder bridges would have damaged the cap and opamp, respectively... anybody else want to tackle that one?

 

[CLock3]

Well, I shortly after posting my reply earlier, I went over to my brother's place to have him help me out, since he did some of this stuff in college, and it definitely went a lot better. It's much better with an extra set of hands. We took out the caps and opamp that I didn't have any extra of and rebuilt it on the other half of unused protoboard. I don't know how I missed the polarity of the cap in the first place either, but when we got to that part today I was like "huh, there's one thing I messed up on" haha. So yeah, now it's fully functional and sounds great, and is put together much more neatly and clean. I'm glad we got it working though, it's gratifying to build one yourself, you know? I'll get some pics up tomorrow most likely. I gotta get an LED holder for the enclosure still. Also, I'm not sure if I'm gonna transfer the stuff to a different enclosure or not as well. I got one off the digi-key site that was mentioned on the guide, and it's pretty nice, but I made a mistake on the front where all the components go, so it's way too cramped and the two 3.5mm plugs will barely plug in because they're too close to each other. You'll see what I mean when I get some pics up. Thanks for all the help everyone by the way.

 

[patton713MW]

Nice job with the fix-up. I have built 4 CMoys (me and 3 friends), and you learn a bit each time. Of course, I saved mine for last so it would turn out the nicest!

 

[CLock3]

Haha, good call. I still gotta get some pics up. I'm heading to my parents' house today though to pick up my iPod dock connector I ordered to make a line out cable to run to the amp. So after I get that made I'll throw some pics up of the pair, haha. I'm still gonna end up getting a new enclosure though at some point. I wish I had known about the Hammond 1455C801BK when I ordered everything, because I would have gotten that one instead. Oh well, haha. The one I've got is fine for now.