Overview
The OS-5020G is a 20MHz analog oscilloscope with function generator. They're from the early 90's, and readily available on secondary markets for much less than the $395 list (I picked up two for about $50 each).
Because they're getting to the age that they need servicing, I've tracked down the manuals and would like to share.
History
The company apparently used to be called LG Precision, then was EZ Digital, and the latter had the website ezdgt.com (now a link farm). Through contacting testequipmentdepot.com (nice people), I was directed to unisource21.com who was also quite helpful and sent me the schematics.
It would seem that there is not a service manual for the -G version (with function generator), but those from similar models seem to apply. The schematics have plenty to debug power supply issues as well.
One thing you'll find when opening up the case, the function generator board feels completely different from the rest of the boards -- this is confirmed from the part numbers.
- PDF Schematics (zip), annoyingly on larger paper than necessary, and rotated oddly.