Help with 1st DIY pls
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swee

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hey,

ive just finished building a headphone amp (was a kit from jaycar)

anywho, my problem is, whenever i listen to it i hear the song plus lots of crackle, so i removed the mount that the opamp was on and put the opamp straight in and when i move the opamp around it goes better and worse. So i moved it to get better, then tried to solder it in, bu by the time ive soldered it, it sounds crackly again.

just wondeirng if it is normal to find it hard to position the opamp to get good sound?

also to add, when there is no opamp in the board, i can hear clear sound just really really quiet, that normal? does that mean everythin else is fine?


mm thanks, i would have used search, but i think its down~ and this problem is bugging me : <
 
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Stephonovich

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No, crackling sound is never normal. And no, you shouldn't have to 'position' the opamp to get it to sound right. I think you may have a bad solder joint or two. Get out your multimeter, set it to Continuity, and start checking all the joints... you're in for a fun time


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swee

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ahah, ok time to buy a multimeter then : p hrmm, well i guess if it worked 1st time, then id have nothing to do for the rest of my holidays, ill keep it positive : >

btw if i dont plan on swapping opamps, is it alright to solder the opamp straight in rather than buying another socket (i kinda wrecked mine whilst tryin to yank it out : P
 
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Stephonovich

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Yeah, a DMM really helps things out. Almost impossible to build most electronics projects without one.

Sure, you can just solder it in. Try not to get it too hot, though. Solder 1 pin at a time, maybe give it 10 seconds between pins to cool down. I'd still recommend a socket if you can salvage yours, though, as you never know when you'll want to try something new. Case in point... I got my CMoy repaired by the wonderful MisterX, (awesome guy for amps/cables/advice, BTW) and he included an Analog Devices AD832AN opamp in the bag for free. (said he bent the pins, and since they were free samples anyway, he didn't feel like bending 'em back) I never would have tried this on my own, as I thought all Analog Devices opamps were harsh and over-bright. I popped this in the socket in replacement of the two Burr-Brown OPA134's that were originally in there, and man, was I a convert. Better bass, clearer treble, and overall, just a better sound.

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swee

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ahah, yea looks like this lil project is gonna cost me abit more than i 1st presumed : p

i might actually buy another kit and have another go at it, cause i really made a mess of the pcb when i was trying to remove the socket cause i thought that was the problem, got stuck, the whole tryin to melt 8 points and pull the socket out got me stumped, ahh well, wat r ya gonna do, its a good learning expeirence tho : >

then again if i bought one from here 1st off, id probably have saved moeny : P
 
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Stephonovich

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Yes, you always spend more than you expect. I thought I would send maybe $40 on my CMoy; ended up being a bit over $100, what with the hook-up wire I had/wanted to get later (Alpha... very nice stuff), the Kester 44A solder (again, very nice, and actually cheaper than Radio Shack since you buy it in bulk), and other things.

Oh, don't worry about how bad you're doing. I did 6 complete re-builds of my CMoy and never once got it working. Apparently the problem was my pot was fried. Heh. Never thought about that. That would explain why I at least got some faint sound when I tried re-building it without a pot...

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swee

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ahh yea, i bet smthin is fried, thats wat the DMM is for right?

so u kinda probe one spot, and the spot after it lookin at numbers, mmm, ill try make sense of it when i get one, suprisingly, they dont look to expensive *few*
 
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Stephonovich

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Eh, I think it's a loose solder joint, since you say you've got buzzing that stops when you wiggle the opamp. Check those. And actually, for continuity, usually there's not numbers, it just beeps if there's a connection, stays silent if there isn't.

And no, they aren't expensive. You can pick up a not too bad one for about $30 USD (~ $45 NZD)

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Kenny12

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dse has a very very cheap dmm for 12 bux... gonna buy it =D anything wrong wif buying dirt cheap dmms? other than bad accuracy.
 
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tangent

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Quote:

anything wrong wif buying dirt cheap dmms? other than bad accuracy.


If accuracy isn't a concern, you can save a lot of money by buying a pair of nails and using them as probes: just poke them at the board, going *beep!* *beep!* and making up numbers.

In addition to inaccuracy, cheap meters can't be calibrated (a calibration costs more than the meter), the build quality is low, and they generally can't be repaired. In a word, they're untrustworthy.
 
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Kenny12

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shouldn't a cheap dmm be at least able to produce a accruacy of ~5%?
 
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Stephonovich

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I'd suppose so, but Tangent would know more about that than I would. I've got a fairly cheap ($25?) RatShack DMM that works pretty well. Measured voltages from wallwarts and the like are equal to what they claim to put out, so I'm assuming it's fairly accurate. Works for now, anyway.

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swee

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heh, i think ill just pick up a cheap one today, since i just really only want to make sure the connections are all there n well


ummm, i dont know if this will make sense but mm, yea



anyways, just wondering since im using a stereo audio cable to hook up to the pot, is ok to split that cable thats not coated, (the one thats neither the left or right channel, guessing its the grounded one) and put half of it on one gang and the other in the other gang?

mm sounds a lil confusin, hence i tried to make a picture of it
 
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taylor

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Quote:

Originally posted by tangent
If accuracy isn't a concern, you can save a lot of money by buying a pair of nails and using them as probes: just poke them at the board, going *beep!* *beep!* and making up numbers.

In addition to inaccuracy, cheap meters can't be calibrated (a calibration costs more than the meter), the build quality is low, and they generally can't be repaired. In a word, they're untrustworthy.


Well, cheap multimeters might not work great for accurate voltage measurements, but they are more than adequate for checking continuity and the presense of voltage. Just not for measuring that voltage.
 
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Dreamslacker

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Quote:

Originally posted by tangent
If accuracy isn't a concern, you can save a lot of money by buying a pair of nails and using them as probes: just poke them at the board, going *beep!* *beep!* and making up numbers.


Man.. You make me crack up...
LOL!
 
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