The first one is typical of the old fashioned wallwart. It’s a transformer to change the voltage followed by a rectifier to convert it to pulsed DC instead of AC. There’s nothing wrong with this as long as the device is designed to accept it, as most devices were a couple decades ago.

The second one is a typical regulated supply, probably an SMPS (switch mode power supply). These are more efficient and have replaced wallwarts (by law) in many places.

The 3rd issue is the rating. Any power supply run beyond its rating could produce problems. A wall wart will sag in voltage and overheat. I’m not sure how an SMPS reacts but I would imagine a voltage sag as well.

Wayne,
Thanks for the insightful feedback.
I think we have enough now to wrap up this troubleshoot. I will merge all of your expert troubleshooting guidance, the photos, and the test point measurements into a single PDF file that we can leave in this thread for others to find should they need to attempt to troubleshoot their own Williams Allegro piano. (Too bad I couldn't get the schematic too.)

For my next project I think I might try to install a Raspberry Pi into a SONY DASH Personal Internet Viewer to convert it into a touch screen science lab monitoring station. I need to do a little research before I'll be ready to proceed on that, but I'll open a thread on AllAboutCircuits when it comes time to connect the Raspberry Pi into the DASH's touch screen panel. That should be a real brain teaser for some of you Jedi electronics engineers, and transplanting a Raspberry Pi into the DASH would give it a whole new lease on life.

Thanks again Wayne! Good night sir...

 

WayneH, Ylli and Ebp,

As promised, I have attached a PDF with the full Williams Allegro Piano Troubleshoot documented, with photos and test measurement results.

Hopefully this troubleshoot guide might help someone else who has a similar problem with a keyboard.

Thanks for your help with this troubleshoot & successful resolution - I could not have proceeded without your expert guidance.

Hope to work with you again on something else just as interesting.

Best wishes,

Alan McRae