I'm sorry I can't provide any further details about where the grounds join together or join back to the grounds from the PSU; I just don't remember. ?One detail I can provide is that it was power rails measured with respect ?to the metal chassis that would change depending on what keys were played, so for example that +11V you are measuring would move around depending on what key was last pressed. That 2K ohms measured from the Mcard Gnd to the +/- 15 V ground sounds fishy to me, but you'll want to confirm of this is correct/expected before you change/add any connections, lest you cause even more damage.
jkjelec
On March 15, 2017 at 8:38 AM "'LucidSound' lucidsound@... [yamahacs80]" <yamahacs80@...> wrote:
I’m keen to know where the grounds should be linked. I’m seeing the M card ground is 0.3 ohm with respect to the logic power ground, but around 2k to the +/-15V ground. I’m guessing that shouldn’t be the case?
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Lucid.
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Sent: Wednesday, March 15, 2017 4:03 AM
Subject: [yamahacs80] One more thing...
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Hi Lucid Sound,
I remember that in the case i mentioned, some of the voltages I measured would change unexpectedly when I played up and down the keyboard, thus giving me the clue that the analog and digital systems had become "floating" relative to each other.
Kyle
jkjelec
