> From: sndgroom@...
>
> Thanks Paul, for the explanation on how to use a scope. I
> agree regarding the good ground, that's why I was using the
> two copper lids on the motherboard, that I surely wrongly
> called "main" ground in the previous message. I need from
> you, if possible, confirmation on where to measure the DAC,
> is it R47 pins a good place? If that's OK, I read a pulse,
> but pretty weak and not well defined.

Yes, either side of R47 is fine.

The R47Hameg pic shows various stepped waves, which is normal, assuming the scale is one or two volts per div. The R47miniscope pic shows a couple of different levels. If you slow the sweep down, you should see more steps. After all, there are 38 sample-and-holds, so there are 38 time-slots in the repeating pattern. They're not fixed width, because the software takes different amounts of time to compute each one. But at 0.1ms per div, you're only seeing a small part of the sequence. If you zoom out to see more of it, and you play keys, you might see voltages moving up and down. They'll jump around horizontally unless you find something else to trigger off with a separate probe, like the SLOW line going to ZX01 on one of the channels.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...