Studio master p7 power supply

[E biddy]

Anyone have this schematic?

[Jazz P Bass]

You have the supply.

Here is a link of Studio Master schematics.

Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics

If you are lucky, one of them will be close.

[E biddy]

Thanks, nothing there. The PSU is called EP-5U. It is the same one used on the mix down classic 8. It is higher current than their other PSUs and uses pass transistors which I'm not real sure about how they work in a PSU.

[Jazz P Bass]

Series Pass Transistors usually have a zener diode on the base connection.

This sets the 'pass' voltage out.

The transistor provides the current.

For higher current applications, the pass circuit may work with a separate regulator.

Power Supply Design.pdf

The first & last page show the two concepts.
The middle portion is the math.

[Jazz P Bass]

Stagemaster EP7 Schematic

Why is that power supply so huge?



I would like to see a gut shot.

Here is what little info I came across.

The EP7 schematic.

SM EP7.pdf

And the EP-5U pinouts.

[Mark Black]

For whatever help it might be there are a couple examples of 'old-school' large mixer PSU implementation in this portion of the Soundcraft 800b manual (pages 18-20):

[E biddy]

Thanks guys.

Mark, the Soundcraft supply is much more complicated than what is going on in the EP5.

Jazz P Bass, The power supply design paper is helpful, it looks like the last example is what is going on in there. That should help me trace the schematic.
It is big because of the huge transformer and a big heatsink. The two main +/-17V circuits have two power transistors in them as well as the 317 and 337 regulators. These boards were designed to be expandable to 40 channels so the power supply needed to be able to handle the current.

[Jazz P Bass]

So what does 'Load A' & Load B' signify?