dumb Alesis 3630 questions and part ordering question
« on: January 18, 2011, 09:44:44 AM »
Hi' I have been looking in the alesis 3630 meta on the mods I bought one of these and really liked the sound then bought another and wasn't quite as good but still alright. I bought them both to mod. I took them both apart and one the one I liked already had the tl084 chips installed but nothing else done to it. The other one just had cheapys go figure. Here is my questions.

It says if the middle side chain quad is a LM324 replace it but it doesn't say what to replace it with. The other op amps it says replace with tl084, tlo74 or MC33079 or similar. Would I use one of these chips for the LM324 or would I use something different?

It says a if there ad a 1uf timing cap to the that 2252 chips check the applications sheet. I looked on the data sheet from the that corp hoping to gian more knowledge on this but it didn't really help me. What type of 1uf cap would I use a ceramic or film and how would I add it? Would I just solder it to 2 of the pins? or would it go inline before or after one of the pins and if so would I remove the trace there?

Is there anything to bias after these mods? There is a couple of pots on the board I'm guessing are for biasing???/ If so where would I take the readings and what should it read?

Another problem is I keep looking up trying to find the sockets for the quad opamps on digikey and just can't find them. Can anybody help me here? Keywords, where to look, or a parts number?

Thanks for taking the time to read this. I'm not a complete noob when it comes to electronics just not full of knowledge either. Any answers would be helpful and if anyone else has any tips or tricks for modding one of these things that would help to.


Re: dumb Alesis 3630 questions and part ordering question
« Reply #1 on: January 18, 2011, 02:35:38 PM »
    This should be on the thread for the 3630 mods, but here is what I can tell you.
LM324-yes, replace with one of the chips you mentioned. They all have a slightly different sound. The LM324 is noisy, and has no business being in the audio path.
Don't know about the 1uf cap.
Try All Electronics for the sockets.
Have fun! It's an easy mod, but don't forget to beef up the power supply caps.
Resistance is not futile. It is voltage divided by current.  (thanks, Bill)


Re: dumb Alesis 3630 questions and part ordering question
« Reply #2 on: January 18, 2011, 04:09:15 PM »
Thanks I won't have any problems with the caps but thanks for the info on the chip and the sockets. If some one could chime in on the timing cap for the 2252 that would of been great. I would of posted in the mod meta thread but I didn't know if that was still an open discussion or even still listed in the lab thank for the help so far though.


Re: dumb Alesis 3630 questions and part ordering question
« Reply #3 on: January 18, 2011, 09:35:59 PM »
I've been reading over the data sheet again for the that 2252 chip and the 1 uf timing cap and It looks like I just run the cap from pin 6 to a ground could I just solder a Panasonic fm 1uf to pin 6 and the wire to like the sleave on one of the ts jacks or at least something similar? Am I at least in the right ballpark or could someone take a look at the data sheet or use some of your guyes superior electronics knowlege and recommend a better way to do this?

Edit:  Pretty sure I answered my own question last night. I was thinking and said to myself there is a ground pin on that chip. So I'll just strap the 1uf cap positive side to pin 6 and the other side the ground pin on the chip. Hope that's right pretty sure it is and at least that's what I'm going to try. Thanks for your help earlier and yes I am a super hero I'm just not going to tell you which one.
« Last Edit: January 19, 2011, 07:19:29 AM by BEEFY »


Re: dumb Alesis 3630 questions and part ordering question
« Reply #4 on: January 25, 2011, 06:05:10 PM »
I might of messed up some I tryed adding the 1uf timing cap to the 2252 chip. I didn't get a ceramic I use and aluminum electrolytic 1 uf 100v and attached the positive side to pin six and the negative side to pin 3 which is a ground. At least I'm pretty sure that is what I did I was guessing pin 1 was the first pin going left to right with the chips label side facing you. It did seem to clean up the sound some less distortion but the leds have gone whacky the red side reads constantly the same level red and that will change depending on how you adjust the threshold and ratio. It also doesn't seems like it's not accually compressing just changing the level of the signal now. Can anybiody chime in and lend a hand here? Anybody anything?

I don't think I have done any irreversable damage. So I can always just remove the cap and see what that does but I would like to get the bottom of this and see whats gong on.


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