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Almost Done with my Cmoy

post #1 of 12
12/14/09 at 2:21am
Thread Starter 
and it wont be tested until the final stage as i do not have alligator clips as shown in the tutorial. This is my first time ever really soldering and i know i need to re go over some of the joints. I think when i first started i was using the wrong type of solder that came with the cheap iron from walmart. Now i am using a weller station with rosin core. Due to some confusion i also had to offset the ground side a bit since i didn't offset the side jumpers properly. Just figured out how to wire the input output jackets by toning with the ohm meter so that will be the next thing I connect. Im guessing some of you may look at the soldering and predict that its not going to work? ....eh open to any critiques



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post #2 of 12
12/14/09 at 2:32am
A lot of those joints look "cold". You can tell because they aren't shiny like the others. It makes bad contact and the amp may not work or you may get a lot of hum, interference, etc. It happens when something in the joint moves while it's cooling. Try re-flowing any cold joints.

What kind of solder are you using? Eutectic solder like 63/37 can help prevent this, although it's certainly possible to use regular 60/40 without making cold joints. The layout and connections look good though.
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post #3 of 12
12/14/09 at 5:28am
I'm about to try this DIY myself, seeing that others are doing it is encouraging!
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post #4 of 12
12/15/09 at 5:50am
Thread Starter 
Quote:
Originally Posted by Juaquin View Post
A lot of those joints look "cold". You can tell because they aren't shiny like the others. It makes bad contact and the amp may not work or you may get a lot of hum, interference, etc. It happens when something in the joint moves while it's cooling. Try re-flowing any cold joints.

What kind of solder are you using? Eutectic solder like 63/37 can help prevent this, although it's certainly possible to use regular 60/40 without making cold joints. The layout and connections look good though.

just found out my solder is lead free , craftsman solder that i found at sears. that explains why the iron set to max temp has such a tough time melting it. I dont want to do the volume control pins since they are so close together until i get some better flowing solder. hopefully i can pick somthing up at radio shack that flows better.

I also assume i want a solder that comes very thin?


I tested everything and just ran the wires thru the pins on the audio jacks on the input side and works! im glad it worked the first time upon completion, hopefully it will still work when i get the volume pot done. Only problem i had other then my layout issue was the red capacitors are too big to work the way i mounted them with the serpac case So i have switched to a Tupperware case
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post #5 of 12
12/15/09 at 6:39am
Radioshack sells 63/37 in a couple different diameters, either of which is fine for a cmoy. Good to hear that it works so far!
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post #6 of 12
12/15/09 at 8:53am
And get some brush on flux.
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post #7 of 12
12/16/09 at 4:32am
Thread Starter 
Quote:
Originally Posted by ozshadow View Post
And get some brush on flux.
what for?


So picked up some 63/37 solder and it works way better! thanks for the advice

anyhow here is the ugly, very first build of mine....last minute case, heh. It doesn't sound better then my Bravo audio tube amp, but id say it sounds pretty good and gives me plenty of extra volume. Im definately going to build another in the future. this one looks so tacky , but not sure how much better i can do, maybe if i plan a lil bit more ahead. & behold.......






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post #8 of 12
12/16/09 at 4:35am
Thread Starter 
Also does anyone know the proper way to remove the op amp? I removed mine after a test & bent all the pins on the way out. Had to bend them back to get it to fit. I need some sort of tweezer that can reach on both sides and clamp under neath so that i dont pull up all from one side.

also want to know how to add a 2nd battery so they work parallel together and not independent of each other.
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post #9 of 12
12/16/09 at 5:44am
Digi-Key - K157-ND (Manufacturer - EX-1)

But an IC extraction tool is no guarantee that you are not going to bend the pins.

FWIW I just wiggle them out with the probe included in this set ---->

Digi-Key - 243-1102-ND (Manufacturer - 20215)

(the one on the right in the picture)
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post #10 of 12
12/16/09 at 8:04pm
I just take a pair of electronics tweezers, slide one side under the chip in its socket, and work it back and forth till it comes out. FWIW I've used fingers many times, and sometimes ended up with eight tiny bleeding piercings on my fingers. Use tools when possible.
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post #11 of 12
12/17/09 at 1:37pm
Juaquin, I've poked myself many times with those DIP8 pins... a tiny "L" shaped allen wrench will slip under the opamp and you can pry up from one side then the other until it pops out...
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post #12 of 12
12/20/09 at 10:08am
Flux helps the solder flow. It will help to reflow joints, or just get them right to begin with. It will cook off and may need to be re-applied. It needs to be cleaned off once you are done.
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