HP 432A Repair Part 7 - Works but way out of cal

[@PixelSchnitzel]

Yes! I would love to see the calibration process. I love to be hands-on, but it's fun to be on this ride with you.

[@tgsoapbox]

Will need to get the proper replacement resistor first and then we can go from there - I also need to update my DMM app so that I can have the values show on the screen at the same time...

[@rikkfaust2829]

My 432a is acting similarly...your lecture has shown me that the power rails are key to making sense of the issue..not a guess.. I will start there and follow your path...Thanks KA3TXR

[@tgsoapbox]

Glad I could help a little - Good luck with the repair.

[@ZoopDragon]

Thanks - interesting, as ever. I'd be interested to see the calibration process.

[@ronbrown1617]

love your work. i too have much of the same equip with which you work, in cluding 4 432as ant the calibrator. i use the 432a to calibrate all my digital pwr meters. yes please do a cal, thanks ron kn6dj

[@tgsoapbox]

Just got the replacement resistor so I'll put that in and do a cal/adjustment video soon. Glad you enjoy the channel.

[@gordonreason1069]

Thankyou your work , very informative , I have a hp432a that has asimilar fault , so you vids should help !

[@TheDefpom]

Could that bouncing around be due to the calibrator output changing, the damping of the meter might be hiding it in some cases.

[@tgsoapbox]

I don't think so - While I haven't had the calibrator "calibrated" recently, I did send it to Keysight a couple of years back to have them do it - Not saying that it isn't, just that I think it is more likely that the crappy resistor (given where it is in the circuit) is causing the problem. I'll get the proper one to replace it (Vishay from Digikey at $5 each - Damn...) and see how it goes. I'm sort of just glad that it is, to paraphrase a movie, "mostly alive" - Not that they're actually worth that much and I already have several - Plus a 431C that I'm going to try bringing back as well. I actually now have more meters than thermistors - I think I have a test equipment problem :)

[@TheDefpom]

@@tgsoapbox I don’t think you have a test equipment problem… if you did then I would also have one, I mean it’s not like I spent $3000 on broken test gear last month is it… oh wait.

[@tgsoapbox]

@@TheDefpom Damn it.....

[@skylabby]

Nice Job , indeed.

[@tgsoapbox]

Thanks - Just as an additional comment, the DMM needs to have an accuracy of +/- 0.05% and be 4 digits - The Fluke 179 is +/- 0.09% + 2 counts - Both my Rigol DM3058 & HP 3458A exceed that requirement so I'd need to use those.

[@gordonreason1069]

checked out what I could .... the only problen I found , was that the 5 khz signal was unstable .... very odd !!! more investigation needed .

[@tgsoapbox]

Is it unstable in terms of Vpp or Frequency? In my case it was Vpp that I fixed by addressing the -13V rail.

[@skylabby]

is it me or this video has no audio?

[@tgsoapbox]

I can hear audio when I play it - Can you try restarting your browser?

[@TheDefpom]

It’s you

[@zdzisiek1979]

🙂👍