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10v diagnostics failure and NBW 200 Hz failure

Question asked by RonCurry on Jul 31, 2016
Latest reply on Aug 1, 2016 by RonCurry

My 8595E is giving me fits. It's giving me a Cal: NBW 200 Hz notch filter failure and several other NBW failures during cal amptd. At times I can get it to complete a cal amptd and if I setup a narrow bandwidth the waveform has odd looking symmetrical notches on the skirts. If I turn off "correction" or load defaults it looks fine. I've swapped every board with a known good board except the motherboard, processor, and analog boards. I thought I had checked the reference voltages but now find that the 10v and -10v reference detector diagnostics give a slightly up slope line in the center of the screen (a fail). However, I've checked the actual voltages with a scope and they appear fine. If I remove the NBW board and place the proper IF jumper on the log boards it calibrates fine for the standard bandwidths. Everything seems to be pointing to the analog board but I'm puzzled that the voltages measure correctly but show failure in the diagnostics. Could the testpoint mux be bad? Can someone give me some pointers?