JLM Modified BA-71A Schematic. Moving R17 out of the -30v power feed and replacing with a link now makes this the 0v ground common.
Adding the R17 in series with the +30v rail makes this a positive powered module. Allowing it to be powered easily by our Power Plant kit or 48v SMPS + TREX kit.
Both Power Plant kit or 48v SMPS + TREX kit options will give +30v to run the module and +48v for phantom power.
Why do you think they did a positive ground system if this simple change was all that was required to convert to negative ground? Just a hold over from when it was necessary to have it for the already installed/operating previous modules/systems that did require positive ground?
The service manuals state that on input and output not to connect outside signal ground to the module positive ground, thus, making this change would lift (ha) that prohibition surely allowing otherwise normal signal connection schemes. To what true benefit I don't know.
