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  #1  
Old 02-06-2012, 11:30 PM
overjoid overjoid is offline
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Default MSA power supply questions

Hello -

I purchased 4 MSA-Rs (some time ago) that I want to pair-up into 2 project boxes and I have some questions.
I'm new at DIY electronics, so bear with me please.

Here's the hardware manual.

Page 4, if I understand it correctly:
To power the MSA, if nothing's connected to the regulated 5V output, I need a wall wart that's 9VDC and 200mA or greater.
If something is connected to the regulated 5V output, I need a wall wart that's 9VDC and 200mA plus the mA load on the regulated output (or greater).

The regulated output supplies 5V up to 100mA and the MSA needs 9VDC and 200mA (or greater).
_____________________________________________

So, I assume that means I can't chain the power supplies from the output of one board to the input of the other board (like I can with the MIDI) since there doesn't seem to be enough power coming out of the regulated output to power another MSA?

If you can't chain the power, will it work if (nothing's connected to either regulated output and) I have one wall wart that supplies 9VDC and 400mA (or greater) connected from the +/- output of the wall wart to the +/- power-in of both PCBs?

I guess what I mean is: can I solder 2 wires to the + on the solder side of the power jack, then solder each of those wires to the + in of each board, then solder 2 wires to the - on the solder side of the power jack, then solder each of those wires to the - in of each board without any extra components?
_____________________________________________

thanks,
Roy
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  #2  
Old 02-08-2012, 11:21 PM
overjoid overjoid is offline
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Default Pizza

I like pizza.
Who likes pizza?
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  #3  
Old 02-10-2012, 05:45 AM
Jim McDougall Jim McDougall is offline
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Yes you can use a big power supply(500-900 ma +) and feed multiple boards ,,, BUT ,,,,
to be safe, you should :
1) wire from the power supply to each board separately -- not daisey chain from board to board -- accomplished by using a barrier strip
2) Put a fuse in each of + lines to the boards - about 250 - 300 ma to protect each board.
3) Do not connect the midi ground line from board to board. The - lines are all wired back to the - from the supply and connecting the midi grounds from board to board will create a ground loop that can cause potential problems.
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Old 02-14-2012, 03:26 PM
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John John is offline
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Roy,

To add to what Jim posted:

You'll want to connect each MSA to the power supply in parallel.

This means:

Connect the 9V power supply "-" to each MSA "POWER IN" G.

Connect the 9V power supply "+" to each MSA "POEWR IN" +.

The total current draw will be the sum of current draws for each MSA thusly connected.

Your power supply must have the capacity to supply that much current, or more.

Hope this helps. If you haven't already found it, this thread may help a lot:

http://forum.highlyliquid.com/showthread.php?t=447
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Old 02-23-2012, 01:54 AM
overjoid overjoid is offline
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Default tnx

Thanks alot!

-R
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  #6  
Old 10-06-2013, 08:12 PM
toomany toomany is offline
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Default power supply

Does the power supply need to be regulated? Perhaps the MSA has its own circuit for this?

Should I be concerned with the MSA's load and select the power supply with the correct open circuit voltage?
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Old 10-10-2013, 02:48 PM
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Quote:
Originally Posted by toomany View Post
Does the power supply need to be regulated? Perhaps the MSA has its own circuit for this?
The MSA includes an onboard voltage regulator. This is what generates the 5V rail for the operation of the microcontroller from the 9V input.

Quote:
Should I be concerned with the MSA's load and select the power supply with the correct open circuit voltage?
I'm not sure if I understand this question. In general, it will be OK to use a power supply with a nominal output of 9VDC. The supplies current capacity should exceed what is drawn by the MSA and any other connected circuitry.
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Old 10-16-2013, 10:33 PM
toomany toomany is offline
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Default Emi?

I was just wondering if one could damage the msa by feeding it too high of a voltage. Some "wall wart" transformers are labeled 9v but output a bit more (obviously once the expected load is applied, they operate around 9). I was thinking since the msa doesn't draw all that much, if one powered it with an adapter that handled, say a 1+ amp load, the voltage might be sitting above 9. Being you have a regulator in there, I now see this as moot.

I plan on mounting the MSA in a 13x10" steel box that will also contain a . transformer roughly 6x3" in size. (It supplies a few things at about 28vac from 110vac.) Does anyone have any experiences with heavy emi causing the MSA to act unfavorably?
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Old 10-21-2013, 08:36 PM
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Quote:
Originally Posted by toomany View Post
I was just wondering if one could damage the msa by feeding it too high of a voltage. Some "wall wart" transformers are labeled 9v but output a bit more (obviously once the expected load is applied, they operate around 9). I was thinking since the msa doesn't draw all that much, if one powered it with an adapter that handled, say a 1+ amp load, the voltage might be sitting above 9. Being you have a regulator in there, I now see this as moot.

I plan on mounting the MSA in a 13x10" steel box that will also contain a . transformer roughly 6x3" in size. (It supplies a few things at about 28vac from 110vac.) Does anyone have any experiences with heavy emi causing the MSA to act unfavorably?
I'm not aware of any. But I suppose it depends on your meaning of "heavy". In any case, I haven't done any such testing, so trial-and-error will be your best bet.
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