[sdiy] MKS70 power supply issue

[james meagher]

Hey Paul - thanks for that funny thought. Indeed my multimeter is
reading peak to peak (max, min, or avg).

Here's what the "7V unregulated" leg looks like on my scope, and with
it is how the +5V leg looks for comparison.

http://www.flickr.com/photos/63824598@N04/8187601216/in/set-72157632011080469/

Cheers,
James

On Wed, Nov 14, 2012 at 10:47 PM, Paul Anderson <wackyvorlon at me.com> wrote:
> I just had a funny thought. Does your multimeter read RMS or peak-to-peak?
>
> If its reading peak voltage, and the 7v line is pulsating DC, then the meter will read 10 volts. 10 volts peak is equal to 7 volts RMS. if you can, put an oscilloscope on that supply and see how noisy it is.
>
> Sent from my iPhone
>
> On 2012-11-14, at 11:12 PM, james meagher <w.james.meagher at gmail.com> wrote:
>
>> Paul wrote: What does it power in the rest of the machine?
>>
>> It looks to me like it's going to the Jack board where it would
>> perhaps feed a PG800 were one plugged in (I don't own one), and also
>> to somewhere on the assigner board, but my copy of the service manual
>> is so blurry on the assigner board schematic I can't really tell where
>> it's going or what it's doing once it gets there.
>>
>> Mark wrote: Is that measurement unloaded? Because that supply line is
>> unregulated, it will likely droop when it's loaded. Maybe 3 volts...
>>
>> I've got everything plugged in, the machine is receiving MIDI and
>> making sound and this out still reads 10V on the dot. But if it's a
>> PG800 it's looking for I can't help it there.
>>
>> Cheers,
>> James
>>
>>>>>
>>>>> You can see the schematic of the PSU here:
>>>>> https://www.dropbox.com/s/jstusojn3610cf6/RolandMKS70PSU.jpg



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