Had a strange problem earlier. I have a 7904A fitted with 2x 7A26 and I suddenly found the probe x10 sense wasn't working on just one of the CH1 PI inputs (the same probe was checked on all four PI inputs). Shorting the ring to ground produced the expected OSD IDENTIFY result but touching a 10K resistor there didn't toggle the OSD to x10 (I think 10K is the correct value for this).
I assumed an internal PI issue but randomly pressing the Identify button and switching both the CH2 polarity and the BW (for no particular technical reason.... they were just there at hand!) the problem just disappeared! A 10K resistor then tapped on the ring confirmed the functionality.
Just because it's now working again doesn't stop me from getting curious about what "fixed" it in case there's a next-time!
Anybody got some suggestion as to what might have been the issue? Obviously the probe sense function is based on the degree of current passing into (out of) the ring; it was working for identify, but not for x10.
