HP 3314A repair notes

[volvo_nut_v70]

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.

[Eddy_D]

I repaired an HP 3314A with similar issues, Err30 across all ranges.
Found the same issue with flaky ribbon cables and replaced with home-made ones; this fixed the front display.
The fix for the E30 issues was replacing a transistor in the SYNC circuit though, which tested good O_o ... it was Q403.

If interested I made a youtube video of the repair.
https://youtu.be/wNxgBubSfH8

Now I am onto another 3314A with more problems... currently troubleshooting an E31 (consistently over-high frequency eg. 1KHz generates 1.4 KHz and the waveform is not 50% or linear (Iup != Idn) so I fear it may be U101 blown on that one...

 - Eddy