Initial design and gathering information

What I have in mind: two supplemental power sockets drilled on the case (will there any room for those? It seems so compact... )

• Dual power for the analog circuits
• "Phantom in" for the phantom power: for now I plan to try stacked 9V batteries (no DC-DC circuit)

From the specs we read dual power supply 18.5 VAC @ 350 mA and "8 W power consumption" Hmm that doesn't add up... is this a reactive load ? C'est une blague: for those interested in knowing when V*I doesn't give Watts see Power factor on Wikipedia.

I found (thanks Google) the Mackie 1604 VLZ service manual complete with detailed schematics of the 1604 power board: this will greatly help me in the analysis of the 402 power section (I guess Mackie engineers don't reinvent the wheel with each new line product...) The 1604 power board gives +/- 16 V, it's a start.

Anyone found the 402 service manual?  8-)

The first thing I'll do is power measurements at the VAC input. Does anyone with experience can advice me for the cell type? Will lead gell cell be OK? Each cell gives 2.1 V so 8 cells would give 16.8 V, enough to drive the voltage regulators? (LM317 et LM337 in the Mackie 1604) or is it too tight and won't have enough headroom to allow cells discharge voltage drops (what is the discharge curve of a lead cell?)

So the next steps are

• Complete drawing of the analog et phantom power circuits with components identification
• Finding viable injection points of external DC power (for analog and phantom)
• Finding working DC values
• Determining cell chemistry and topology.

C'est tout!