Fluke 883A alignment help - Page 1
Forum section: electronics / general

author: C-47
author_rank: Regular Contributor
timestamp: March 24, 2025, 06:44:17 am
content: Since getting the 883A functional several years ago with forum members help, the thing has sat a bit lonely, but now is the time to return to its former status, I hope.The problem though is the manuals I have seen / have, do not clearly show the circuit board graphics to locate the test points for alignment, does anyone have such or know where these are obtainable or any other info that will assist.The 883A info is a bit thin, the 887A though, is a bit more informative, but from what I can see, some component details differ from the 883A.I'll use an in cal 34401A for alignment.Thanks for any help or pointers on this. Alan.

author: J-R
author_rank: Super Contributor
timestamp: March 24, 2025, 10:29:34 am
content: Another thread with 883A photos and info:https://www.eevblog.com/forum/repair/fluke-883a-differential-voltmeter-(pics)/Manual:https://archive.org/details/manualsplus_03433/(PDF download:https://archive.org/download/manualsplus_03433/manualsplus_03433.pdf)OP's prior 883A thread:https://www.eevblog.com/forum/beginners/fluke-883a-voltage/Based on what I read via those links and what I see on your bench, I would suggest leaving this 883A as-is for now:- VREF-01 5V reference is "guaranteed to be between 4.9995 and 5.0005 Volts for a minimum of 8 months" which is not really adequate for the 883A in this case. I have one and it drifted up quite a bit in the first year, similar to what I see on your 34401A, maybe a bit worse.- 34401A in your photo was last calibrated in 2019, so it may not be adequate either, unless you have a lot more references to check it against.- 883A calibration procedure is quite involved. You'll need some more equipment for sure.- 121GW can't play in this playground, unfortunately. It will just cause trouble.

author: C-47
author_rank: Regular Contributor
timestamp: March 24, 2025, 09:03:33 pm
content: Thanks J-R for the comments, actually any justification to buy more test equipment has to be good (TEA), don't know if the wife would see it that way though.Agree on the 121GW was only there as a ballpark indicator, the 34401 was calibrated mid 2023 but sticker is on top of the unit as I didn't want the several Keysight ones covered / removed. Thanks, the manual links had some better graphics than the ones I had, so hopefully easier to find the test points, will see which rabbit hole this leads to now. Thanks, Alan.

author: J-R
author_rank: Super Contributor
timestamp: March 24, 2025, 11:51:26 pm
content: Are you referring to the test points for the Kelvin-Varley divider section or something else? I don't think you would have to touch those unless one of its components was replaced.

author: C-47
author_rank: Regular Contributor
timestamp: March 25, 2025, 12:26:52 am
content: No, it is the test point for the 18v line which I have now found and adjusted as it just over 1v low, so to carry on with the others in the area as necessary. Don't want to touch the KV section as don't have the equipment for such. Thanks.

author: C-47
author_rank: Regular Contributor
timestamp: March 25, 2025, 10:02:28 am
content: Just an update on a piece of equipment that is around 60 years old, the design of which is a credit to the design engineers and others of the era, I doubt that modern stuff will still be good in 60 years from now.I have managed to do the null and voltage adjustments for the 1 and 10 volt ranges, as J-R mentioned its a bit of a convoluted process, one thing I see is my Advantest 6144 voltage source is not really up to the accuracy task, but what to do, it will have to suffice for now. The 100v range is only done to 32v max output of the 6144. Thanks again for the help.