Debugging
- confirm that all LED's are on LD1, LD2 LD9, and LD10
- measure voltages at TP23 - TP28 (they should be within +/- 10%)
- if voltages are OK -> most likely the short is on the "signal path"
- if one or more voltages are out of spec (usually lower voltage) -> most likely a short on power pins (os power inputs of one of the chips)
- debugging signal paths
- switch to IV mode
- select channel 0
- for channel 0 resistance between switching card input (left-hand side of the protection resistor) and ground should be high >> MOhms
- for channel 1 (or any other) resistance between switching card input (left-hand side of the protection resistor) and ground should be around 10kOhm
- check the impedance between the selected input (S1..S8) and the output (D)
- debugging multiplexers
- switch to CV mode
- measure C for all channels, the result should be a step structure with periods of 8 and absolute values around 100 pF.