I have absolutely no clue what you are asking or what your schematic shows.All I can determine is that the transistor connected to R5 is turned off, and the transistor connected to R6 is turned on.Since you don't show what the collectors of the transistors are connected to or what the sensor is, I can't begin to guess if this is normal.
Hi,Using this diagram.With the black/neg probe of your DMM connected to the gnd of your circuit;Measure DC voltage at A, B, C , D with NO WATER and using the red/positive probe of DMM.Measure DC voltage at A, B, C , D with WATER covering BOTH zero and 20% wires using the red/positive probe of DMM.Thanks.. Tom... PS. Have you checked your tank probes for corrosion due to electrolysis?
no WaterA = 3.5mvB = 4.97vC = -345mvD = 4.97v
in WATERA = 0.753vB = 9.2mvC = 0.755vD = 9.4mv
A, B, D: perfectly normal.C, not so much - the main oddity is that it's negative. Galvanic potential from two dissimilar metals maybe?Perfectly normal.