HP 6038A Power Supply: Calibration with GPIB Controller
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- Опубликовано: 12 июл 2024
- A viewer requested a follow up video on this HP 6038A power supply that I repaired and conducted performance evaluations on. So in this video I calibrate the unit with my newly acquired GPIB controller.
Note: in this video I use calibration standards that are not necessarily qualified for some of the calibration steps. I did this calibration just for fun and this is my personal equipment that will not be used for any critical measurements. Be sure to use the correct calibration standards if you plan to use this video as a reference for a serious calibration of the unit.
Repair of unit here • HP 6038A Autoranging P...
Performance testing here • HP 6038A Power Supply ...
0:00 - Overview/test of GPIB controller
6:03 - Voltage Monitor Zero Adjustment
13:07 - Common Mode Adjustment
15:27 - Remote Readback Zero Adjustment
19:07 - Constant Voltage Full Scale Adjustment
21:10 - Voltage Monitor & Remote Readback Full Scale
25:38 - Constant Voltage Zero Adjustment
27:40 - Current Monitor Zero Adjustment
30:57 - Constant Current Zero Adjustment
32:53 - Current Monitor Full Scale Adjustment
35:20 - Constant Current Full Scale Adjustment
36:26 - Power Limit Adjust & almost killing the unit!!
40:28 - Resistance Programming Full Scale Adjust
43:10 - RIFA X/Y caps replaced!!
43:28 - Conclusion 
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oh, no comments…what a buch of “party poopers”!
wel I REALLY enjoyed this little party! R40, “Come on Louie, Come on Louie” hold your tongue at the correct angle as instructed by Dave!
I opened three indtances of the manual to “play along with you”, one indtance was looking st the cal indtructions you were following and the other two instances were looking at the circuit, one st the A2 “mesh” board and the other st the A8 GPIB board.It was easy to find the pots you were tweaking, nut I found it much more difficult to work out where you had the DMM connected on each test, but I still gotbthe general giist of it.
The very first thing you did was to zero the DC offset of U7, and I assume you had the DMM somewhere around R1/CR8 monitoring the output of U7. Now if you ever “run out of pot track” as you did with R22, but lster, when adjusting the CMR with R21 and got in within limits…it often pays to go back to R22 and adjust it back away from the endstop, yhen come back to R21 again and pull the reading back the other way…you “itterate” back and fourth between the two steps until you get your desired reading but also end up in a condition where both R21 and R22 still possess some leeway either way and neither is jammed hard up one end.
You did exceptionally well with the equipment you had to hand, it was a few percent out and you reduced thst to about 0.1% out. Calibration is not about being perfectly on, but getting as close as you can with the gear that you have.
I have an AC DC voltage reference here, it has fancy cal stickers and dates all over it….last calibrated by the Nationsl Standards Lab in Canberra in 1997….And scheduled to be redone in 2003…but it was sold off before then. I sctually contacted National Standards…arrogant prats who wondered why I had bothered to call, but they said they would cal it again for me against the Australian National Voltage Reference for AU $ 10K!
So, yes primay calibration against your Nation’s standard is for the duper elites, but the rest of us can still do reasonably well.Assume you get to gether with 50 other electronics guys and ask them to ALL bring ALL their multimeters and oscilloscopes, then you test ALL this gear against the 20 year out of date cal standard….the bigger the sample of gear, the more precise a group can get all the gear to read virtually thr same, now it will probably be lower in accuracy than precision, but with a big enough pile of gear the precision could be assumed to be of a fairly high degree…because some people’s gear will drift low whilst others’ will drift high and, hopefully those drifts will largely cancel out.
Would actually make a pretty interesting experiement if the whole You Tube electronics community did this, then paid to compare the results to a national standard!
Those two procedures in the current calibration you felt were the same procedutr repeated twice, the first one was adjusting R9, the gain of the current sense amp U1, and the other was adjusting R55, which is the reference level to DAC U9 from U5, the master reference, so one was ensuring the load current was being measured correctly and the other was ensuring the SET current command from the GPIB via the digital section was also correct, these two are compared in U2B which looks like some sort of null measurement comparator.
I feel, least for me anyway, that following along in the circuit (as well as following instructions) gives you a better inkling of what you are actually doing beyond just the blind instructions. In most pieces of gear…and it could be anything from radio transmitters to x-ray machines will possess much the same principles, diff amps, instrumentstion amps, sense amps, comparators, VCO’s, phaee locked loops etc, etc. So cal steps will usually be of just a few categories, gain adjustment, offset adjustment, common-mode rejection adjustment, frequency ot beat adjustment, comparator trip adjustment etc. Over time as you gain experience, you will learn to recognize which adjustments, gain ror example, you sre making and get a much more intuitive feel for it…like realizing that itterating round and round between gain and offset adjustments may be required to go on ever smaller circles each itteration to get ever closer to the desired outcome. And it is far easier to do on your own gear where the onus of responsibility is only back on you, but mskes you better when on other people’s gear too.
When you did the last pot, I could “feel” the wiper springing back a few tens of milivolts when you took the screwdriver out of the slot of the pot…it one stage I was literally yelling st the screen, why didn’t the bloody designer put a 10turn pot in thst position!
So, yes, thanks for coming back to it….and Please, please, “wipe it’s poor snotty nose”…get some ethanol on some loo psper and clean all that stickey smut off the front pannel!
Thanks Globe Collector I did this one for you! I really appreciate you always taking the time to write a detailed comment. I think I might go back and take another look at the V-Monitor Zero & Common Mode cals as well as the I-Monitor and Constant I full scale cals.
Yea I could make a better attempt to understand the circuitry. I recently bought 'Art of Electronics' and have been slowly reading it. Ideally, I'd like to be doing these repairs and reading through this book at the same time, but there's only so much time in a day - feel like I don't have enough sometimes 😂
I love that idea of gathering a bunch electronics hobbyists/professionals and checking each others equipment! I feel there was a thread on the EEV blog forum where a group was doing this!
I also appreciate you not slamming me for not using the correct standards/equipment. I tried to make it clear that this procedure was just for fun on my own personal equipment that won't be used for any critical measurements. But I'm sure someone will still comment saying I committed some kind of sin by doing this 😂
I'll be sure to give the unit a good cleaning with 70% EtOH! If you have any video requests in the future, just lemme know!
I feel that we all can only do the best we can with the gear we have, (or can beg, borrow or steal), the 3478A was a “real little trooper” and had enough digits for most of the tests, and where it didn’t, well you got within 500uV as opposed to the specified 120uV.
Not many of us can afford a HP 3458A, let alone a 3456A.
You might want to look up Colin Mitchell’s “Talking Electronics”. Here in Australia we had a very strong electronics publishing community…we even had our own long running electronics magazines, “Electronics Australia” and “Electronics Today International” which collectively covered about six decades of electronics in Australia. Dave jones interviews both Colin Mitchell and Doug Ford, (Rhode Microphones/Jands PA Amps), on his EEV 1 channel, both ste very good snd informative videos.
I can’t “slam”you for the gear, or lack thereof, you have because I’m in much the same boat and I have to make the very same compromixes you had to. My best DMM is only 3-1/2 digit also.
One thing I will say though, particularly at this time of the year, (the “interweek” between Christmas and New Year), don’t neglect time spent with your partner! All my electronics activity is basically “on hold” from the 23rd of Dec to about the 3rd of Jan as my partners birthday, Christmas and New Year all fall in this timespan and family/relationship commitments come first!
All good points! I'll check out Colin and Doug and see if I can dig up any of those magazines (if they are online). And thanks for the reminder! I get too carried away sometimes. I'm sure you understand 😂 Fortunately my partner and I have spent lots of time together and with family this holiday. Glad to hear you have been able to do the same! @@thanhhuynh272
Great job!
Sometimes you have to go with what you have, it's just how it is. :)
Thank you!
Thanks for the video. I still need to calibrate my 6033A. I do have the receptacle for the test connector (board edge) but need to make a breakout PCB with it to make it easier to connect to those test points.
Thanks for watching! Yea that J3 connector is such a pain to probe without that test connector - and a breakout board would be even better. Then you can easily leave the shielding on the unit. This procedure is definitely applicable to your 6033A with some slight changes. The shunt resistor is a 0.010 instead of 0.1 ohm. And obviously the settings will be different. Just remember to have the correct calibration standards unlike myself here 😂 But all and all it's not a bad procedure and it doesn't require all that much as far as materials!
Also, I recommend using this copy of the service manual. It's much better resolution than what Keysight's website has available ridl.cfd.rit.edu/products/manuals/Agilent/power%20supplies/CD1/Service/6033Aser.pdf