Re: HP8643A Displays Result Code 14.020122
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On Wed, Aug 28, 2019 at 6:27 PM Mike Besemer < mwbesemer@...> wrote: Now it¡¯s throwing random hardware failure codes with 14 (p/s) being common each time.? Rechecked the power supply with a plotter and the 5.2 VDC is low on startup and climbs slowly toward the lower acceptable limit.? Need to get the CLIP downloaded to troubleshoot further.
Sadly the CLIP is not going to help you with the power supply, when you crack'er open you'll find two COTS switchers in there. One powers the oven for the high-stability oscillator and the soft power on, the other one powers the rest of the instrument, and the CLIP has schematics for neither one. Thankfully I found that a full recap just fixed it(TM) in mine. I don't remember how hard it was to get at the PSU, but you might try just tacking a new cap over the 5.2V smoothing cap for a quick and dirty diagnosis.
I just went looking for photos, and it looks like the PSU drops out the bottom of the instrument. There's a "filter" board downstream from the PSU, and it's chock-a-block with inductors and smoothing caps, which is probably why no ripple shows at the IO board even when the PSU caps are gonsky.
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