chopping a mixer from 24ch to 12

[Aud1073cH]

I'd like to get your input-

Someone handed me an old Biamp 24 channel mixing console (2442) that they'd stripped the XLRs.
The price seemed right (free).

Because it is so old, it takes a lot of space - about 48" wide, 30 some-odd inches deep. so I was thinking about chopping it down to 12 channels, w/sub and main sections. comes to a more manageable 30" or so wide. The electronics seem simple enough - just disconnecting the unwanted channels from the buses, and cutting the panels down, and adding a couple new holes for screws.

But what would be a clean way to cut the panels down to size? too thick for tin snips/shears. a sawsall would be a bit too messy.
What do you suggest to get a clean cut?

The mixer also came without its external power supply - so I'll have to figure out what the power requirements are (I suppose I should do this first.) I've got the power cable - so If I need to build my own supply I can... If I get lost I'll post something in the power supply section.

[drummer_Dave]

you should be able to use the same power supply (assuming it still works) it will just be over kill. as for cutting it down it depends on what type of material the chasis is but im sure a table saw with the appropriate blade would do the trick (im sure you could find a local shop to do it for $5 - $10)

as for the electronics I would look and make sure that when you disconnect the extra channels you don't leave summing buss inputs floating, tie them low or maybe redo the summing buss block on some strip board or something. If you were able to come up with a schematic that would help alot. Good luck

Dave

[Aud1073cH]

Thanks Dave,

I didn't see any termination on the busses on my first peek inside. there are about 22 buss wires - two harnesses of 10 wires each made of flexible wire with inline connectors that plug into each channel strip pcb, and two made of solid buss wire. I figure I'll snip everything between channels 12 and 13, and remove channels 1 thru 12. But I'll check to see if there is any termination at channel 1.

There is no internal PSU - just a 16 pin connector that only has 12 pins. I'll need to do some more disassembly to see if they are labeled inside.

I've searched a few times online, and havn't found any manuals or schematics.

I think I may know of a metal shop... The panels feel like steel.

same model as this one: (someone else's photo)

[drummer_Dave]

o sorry i misread the post, you said it came WITHOUT the PSU, my bad. Im sure it will have +/- about 15 - 18 (depending what opamps are used, back in the day to get more head room they would sometimes increase the supply to opamps and push the limits to achive greater voltage swing.) I would bet you could build a psu capable of +/-15 at about 2 amps and you would be safe. Maybe use a 7815 with a pass transistor (do a google search and you could find something) or be real lazy and just parallel 2 7815's and that would work up to at least 2.5 amps.

the better way would be to trace it out and see what feeds the opamp section and power it with a bench supply and read the current drawn. there probably is a 5V or 12V line some where for digital stuff.... just my guesses though. What is the actual make and model or your mixer (cant enlarge the picture)

Dave

[Aud1073cH]

Biamp 2442

the model no. refers to 24 channels, 4 bus, 2 main (L/R)

[dangus]

Remove a couple of channels "with extreme prejudice" and make a rough cut through them using a Sawzall, or possibly a Skilsaw with a metal-cutting fiber disc. Mask off the rest to keep filings out of the pots and switches.

Scribe a cut line, or mark it with tape, and cut carefully with cutoff wheels in a die grinder or Dremel, or use a pneumatic or electric sheet metal nibbler. If the edge is a bit rough, file it flat, or hide it with a groove in the wooden end panel.

A pneumatic hacksaw could be narrow enough to fit, and should make a clean cut in one go, if you just stripped one channel to get the knobs etc out of the way. Lay down some "Painter's Mate" masking tape and mark the cut line; it should protect the paint from chipping.