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Repairing Alesis 3630 myself



RemyRAD Wed, 07/26/2006 - 17:23
Unfortunately, the 3630 is a bargain unit. Most of these bargain devices are almost not worth the effort to repair since much of it is now surface mounted components. I've never opened up one of those so I'm really not certain?

Are you sure you are engaging the stereo coupling button? Your stereo mix will not sound right if you don't. The image will appear to wander from side to side. If you have engaged the switch and levels still do not seem right, try feeding both channels from a single monaural source and see if the problem continues? It might not be the VCA? It could be an output or input Op-Amp problem? Feeding both inputs from a mono source while monitoring in stereo should reveal whether the VCA is doing its job. You can make up the level difference on a console in that way, you can definitely tell whether gain reduction is happening or not, equally for both channels.

Everything that starts off cold, whether it's tubes or transistors all has to warm up. I used to marvel over the fact that it actually took approximately 3 hours for our Ampex and MCI 24 track recorders to actually stabilize, even when they were new! I use to work for Scully and they weren't any different either. So perhaps a good one half hour of warmup is in order for your 3630 to finally start to function consistently?

Remember, never try to feed a stereo signal through a stereo limiter without engaging the stereo coupling switch. If you don't, everything you do will make you sound like an amateur.
Ms. Remy Ann David
Ms. Remy Ann David

JoeH Wed, 07/26/2006 - 19:26
There's a lot you can do on your own, just in terms of simple maintenance and perhaps sort out the problem. (I agree with Remy in principle, it's probably not worth fixing; BUT if you're up for it, you might learn a few things in the process.)

Get a good Volt/Ohm meter and check for basic stuff. Dunno if it's a bipolar power supply or not, but it's possible. Be VERY careful when working with the AC side of the power supply (esp if it's plugged in!). Always work on live stuff with sneakers on (no bare feet), standing up, and one hand in your pocket. I'm serious.

The unit is certainly small enough in that you could re-solder just about every joint on the thing (esp anything that looks suspicious). Use a magnifying glass if you're in doubt, and check for cold solder joints, extra blobs of solder, etc. (You don't want to make things worse than when you started). You may end up "curing" it by simply gently heating and applying some new solder to each connection.

You could also replace all the ICs with sockets and then reseat them. This makes it a little easier next time you have to do some work on it. (With ICs in sockets, you can also do A/B testing a whole lot's a miniature version of parts-swapping at the chip-level, but sometimes it'll get ya outta there in a hurry.

I'd also check any and all caps; esp if they're electrolytic and prone to drying out. That may be part of the problem, as well.

Of course you'll want to clean all pots and in/out jacks, sometimes that's all it takes. If it's a balanced i/o circuit, make sure the tip, ring and sleeve pins are all solidly connected to the circuit boards and are making good contact when a plug is inserted.

have fun, and try not to blow anything (or yourself) up in the process! 8-)

moonbaby Thu, 07/27/2006 - 06:16
There is an online store-Black Lion Audio-that offers upgrades and service parts for the 3630. My service tech did mods to a couple of 3630's and they actually turned out pretty well. That box, as from the factory is a POC, but the Black Lion mods really cleaned up the sound and stabilized their operation. Google Black Lion Audio and check 'em out...
BTW, I learned about these guys on this forum. There has been a lot of positive response regarding what the mods do to the 3630 and they also do other less-than-stellar boxes. You can only shine a turd so far, but they make 'em decent!

MadMax Thu, 08/03/2006 - 19:10
bpatram wrote: Got my opamps in the mail today and jumped right to putting them in. I didn't buy any sockets I wish I did kind of stupid on my behalf. So I desolderd the old ones, no wick I used a pump. Got them off ok without any damage and then put in the new ones. Which I find are not the same brand! Stupid Jameco gave me the same # IC but from 2 different makers (TI and ST). I power up the unit and its still uneven but switched sides! lol I have no clue what that means but the unit does work and sounds fine. I think it fixed the drifting I had with it, not 100% sure. So in the end I really didn't fix much but at the same time just glad it still works. :?

A quick thing to ask/comment...

You did label/mark which original opamp came from which side, right? If so, break out the sloberin' iron again, and replace the waeker side with the stronger side original.

With any luck, they'll be fairly close to each other... just a thought.


Member Thu, 08/03/2006 - 23:13
Thats good reading and info thanks. The old opamps are destroyed as I had to cut them out for a better removal. I just find it interesting that I replaced both and the result was the same uneven return but on other side. Granted they were not the same brand, maybe I'm getting closer to the solution. I'm not sure if its the left being too low or the right being too loud. I'll deal with it though. I think I am just going to put it in my PA rig for ducking only, maybe I will open it up again some day. :o
Thanks Guys

JoeH Sun, 07/30/2006 - 14:30
Again, make sure you put in sockets for those ICs. If you are going to go through the hassle of taking the old ones out, do yourselves a favor and put in sockets, so the next repair/upgrade will be nothing more than pulling a chip out.

Careful with the soldering iron and use a wic, too!