scope voltages skewed
I've had two of the MODIS's now and both were built around 07-08. Only one is still functional. Both of them have skewed the voltages to the negative. For example; if I connect the scope to a known good five volt reference and reference ground circuit, both voltages will report .3 to .5 volts to the negative. That means the 5 volt will only show 4.7 to 4.5 volts and the ground will show -.3 to -.5 volts. I don't see an option in the MODIS to calibrate myself. Anything I can find for a manual offers nothing to troubleshoot this. I bought the second after the first got wrecked. Because I knew the first had that problem, I didn't buy the second without confirming correct operation and it did fine. I tested three channels on a MAF sensor and voltages were true. I bought it and its been angering me with skewed voltages since. The second was pretty bare for accessories and hardware, but the first had nearly everything, so I used the scope leads from the first. They are Snap On leads, if that matters. Each MODIS does have its own scope plug in cartridge and each has its original cartridge installed. They have not been removed or swapped between the units. So is there a way I can calibrate this scope by myself? Are those scope leads somehow at fault? Thanks in advance.