Studiomaster 16-4-8 latest on 13 October 2008

Hey man, hope you had a great weekend
did you see the weston beach race?
or did you stay at home and enjoy the weather?
ive taken on the job of Mixerlock Homes and trying to disyfer/dysifer(check spelling on that ONE) the mixer schematic and pcb trace on the PSU schematic it reads +15vB? what does that correlate to?
Now on the schematic for the bussing for power/auxes it reads 0VIN, 0VA, 0VF? what does that correlate to I know they are all earth(correct?), and on the picture of bus strip wire they are all green. Does that mean all of these would go to earth strap(ground)?
Ive figured out from the PSU scematic and my picture of PSU the color code as follows: Pink = +48v, Red = +15vB & +15v, Green = 0v thats enough for this email
thanks paul


  1. Sometimes it’s to make cascading wiring easier. Sometimes it’s to make
    sure that there is enough capacity for the return supply feeds.
    Or it’s a combination of both!
    If there are several earth/0 Volt feeds, then care has to be taken to
    ensure earth loops aren’t generated – hence my personally preferred
    use of a big blob of an earth made from the tag-strip I mentioned
    earlier i.e. it’s pretty hard to generate an earth loop on something
    that’s only two inches long!


  2. Cool thanks
    ive got to go over your other notes again as i dont understand the difference between the PSU ground which all the channels are connected to, plus the ground from the monitor channel to chassis, and the kettle plug groung to chassis thanks

  3. Watson here.

    +15Vb relates to the second independent +15V supply.
    The other one should be called A but they were too lazy or they assumed that it’s obvious to most people what it means – obviously not in your case, as it’s all new to you. Like any business or work, there’s a shorthand that people use….

    The same chip is used to produce 48V & 15V! It’s datasheet is here
    You’ll see that the O/P voltage is set via the resistor chain, which explains the use of a 1% tolerance resistor for the larger one.
    Anything worse and there will be too much error.

    I can’t see everything at work, but the various O Volt connections are just that, I think. There is probably a bit of numbering or assumed numbering to the connectors.
    Maybe the connector goes A,B,C,D etc and then you’ll know which pin has the OV. ?

    Ultimately though, they all connect together in the PSU.

    Colour coding of wires is good. That’s one disappointment about the mixer loom….all the wires appear to be yellow! Ha Ha! At least they’re in order, but if you ever need to separate…..


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