Taken from the 475 manual, the Z-Axis has the following characteristics: Sensitivity: Positive-going signal from ground decreases intensity 5 V P-P signal causes noticeable modulation at normal intensity Maximum Input Voltage: 100 V (DC plus peak AC) 100 V P-P AC at 1 kHz or less Useable Frequency Range: DC to 50 MHz. I take the sensitivity spec to mean that you need AT LEAST 5Vp-p to see any intensity modulation. To completely blank the trace, you need more than 5Vp-p. I haven't used the Z-Axis on my 575 in recent memory, but it makes sense that you will need to (A) check the amplitude and polarity of the signal you're feeding to the Z-Axis, (B) amplify it to an amplitude that will give you the needed blanking level, and (C) invert it if necessary to give a positive-going pulse with ground reference. Getting sufficient amplitude to completely blank the trace will likely require some experimentation, but shouldn't be difficult. If I were doing this, I'd start with an amplifier with a gain of 2x to maybe 5x and see how that works. My guess is that it will take a pulse of around +10V to give complete blanking. Cheers!! Dave M _______________________________________________ Techtoolslist mailing list Techtoolslist@flippers.com http://seven.pairlist.net/mailman/listinfo/techtoolslist