09-02-2026, 02:30 PM
MrFixr, I have an OWON PC o-scope, but to my embarassment and shame, I have never learned to use it. I'm going cross-eyed 
going over the components and comparing (tracing) to the schematic. I've noticed that the US 50-520 has a 150K resistor (R100) between the floating ground and chassis ground, where the 81 doesn't have one. Also, the 81 schematic (and the 50-520) has a dotted line conection in Section 4 labeled C101C. Anyway, I'm going to hold back for a couple of days and come back to it with a hopefully fresh mind 
. Joe
going over the components and comparing (tracing) to the schematic. I've noticed that the US 50-520 has a 150K resistor (R100) between the floating ground and chassis ground, where the 81 doesn't have one. Also, the 81 schematic (and the 50-520) has a dotted line conection in Section 4 labeled C101C. Anyway, I'm going to hold back for a couple of days and come back to it with a hopefully fresh mind . Joe
Courage will follow when Faith takes the lead.
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