Synth-DIY Yahoo! Groups Archives

Power Question -- Adding +5v

2006-01-09 by Tkacs, Ken

Would someone on the list be so kind as to check my thinking? The only thing about my modular that’s a real gray area for me is the power supply portion. I’m no engineer, and the fact that the voltages involved are dangerous, coupled with the fact that I could burn out my modules, means that I cringe in terror whenever I need to work on the power supply.

But with the MOTM-650 around the corner, I guess it’s time to start thinking about adding that +5v rail to the cabinets.

I have the new MOTM power distribution board on order, the one with the new 6-pin connectors (http://www.synthtech.com/images/m990large.jpg). And I have some +5v PowerOne supplies on hand. I’m thinking that I would wire one in the following way… someone please yell if I’m about to do something rampantly idiotic.

- The AC power comes into the cabinet.

- Split it so that it goes to both “center pins” of a front panel DPDT switch.

- From there, both the +/-15v and 5v supplies are wired up independently, but the two chassis frames are bolted together (someone a while ago indicated that multiple power supplies in a system should have their frames electrically connected).

- Run lines (12 gauge wire) to the power distribution board from each supply to the appropriate screw terminals on the distro board.

Thanks in advance for any life- and system-saving advice!

Ken Tkacs

Re: [motm] Power Question -- Adding +5v

2006-01-09 by Scott Juskiw

I did this exact thing on one of my cabinets. I already had a MOTM-900 power supply in a cabinet and bought a separate +5V supply to handle the newer modules that need +/-15V and +5V. These two supplies hook into a MOTM-990 power distribution board.

What you describe will work fine. Just make sure you have fuses on the HOT side of the AC for each of power supplies, because they are independent. You don't need to bolt the two chassis together, you can just run a fat wire between them that connects to earth ground. You also need to hook a wire between the 0V terminals on both supplies so that "ground" on the 5V supply is at the same potential as "ground" on the 15V supply (this is not the same as earth ground).

I've posted some pictures of my power supply conversion here:

http://www.tellun.com/motm/darmok/power/Darmok_power.html

I suppose I should draw a schematic to show how it all hooks together.

Would someone on the list be so kind as to check my thinking? The only thing about my modular that's a real gray area for me is the power supply portion. I'm no engineer, and the fact that the voltages involved are dangerous, coupled with the fact that I could burn out my modules, means that I cringe in terror whenever I need to work on the power supply.

But with the MOTM-650 around the corner, I guess it's time to start thinking about adding that +5v rail to the cabinets.

I have the new MOTM power distribution board on order, the one with the new 6-pin connectors (http://www.synthtech.com/images/m990large.jpg). And I have some +5v PowerOne supplies on hand. I'm thinking that I would wire one in the following way someone please yell if I'm about to do something rampantly idiotic.

- The AC power comes into the cabinet.

- Split it so that it goes to both "center pins" of a front panel DPDT switch.

- From there, both the +/-15v and 5v supplies are wired up independently, but the two chassis frames are bolted together (someone a while ago indicated that multiple power supplies in a system should have their frames electrically connected).

- Run lines (12 gauge wire) to the power distribution board from each supply to the appropriate screw terminals on the distro board.

Thanks in advance for any life- and system-saving advice!

Ken Tkacs