Just had to repair a faithful HP 3314A. It was throwing E30, E31 and E34 errors on start up and during ranging. Looks like it was bad connections on the A1 board to the connectors going off of it, corrected by unhooking the ribbon cable, flex connector cable and signal connectors then extracting the board off the two connector that penetrate the board, J3 and J8. Errors went away on reassembly.
Since there are a number of loops, DACs and 2 custom ICs U101 and U502, I went through and made some troubleshooting notes and waveforms. Note I set the O/P for triangle out at 1 kHz 1 V since the native waveform is a triangle.
Note that the two troubleshooting flow charts are useful for more than CAL errors, the U101 DAC verification procedure works like a charm since the DACs two complimentary O/Ps are current waveforms, the verification is a simple way to test U101.