Fluke 8840A/AF questions - Page 1
Forum section: electronics / testgear

author: BillyO
author_rank: Super Contributor
timestamp: October 23, 2024, 01:57:03 am
content: I know some of you have good experience with this meter so I have questions for you.I have the opportunity to get one for as little as $100 USD. It is said to be in working condition, fully tested, in decent physical condition, has a 2022 calibration but has a fairly dim display.1) Is it worth $100?2) What else should I look for before I part with my cash?3) If I get it I'm considering AHOL's display replacement - is it well regarded?

author: J-R
author_rank: Super Contributor
timestamp: October 23, 2024, 03:15:12 am
content: Is it actually the AF version with the ratio labels?Does it still have the AC board installed? Supposedly all AF versions shipped with the AC board, but someone could have removed it. Double-check if you can. GPIB?All of that for $100 seems like a fine deal, although maybe not quite as much if the display is essentially gone.Despite a reduced feature set compared to modern bench DMMs, I think with a recent calibration it should perform those limited duties well. Are you sure you're OK with those missing features?My concerns with AHOL's display would be the smaller text and the long shipping time.

author: AVGresponding
author_rank: Super Contributor
timestamp: October 23, 2024, 05:22:22 am
content: The AC-09 option can, at least, be fitted without problems, though iirc the GPIB needs a different FW? Not sure on that...If the cal is recent, it's likely still good, barring faults; I got mine (8840A, AC-09), oh, seven years ago, with cal stickers over a decade old, and it passed a cal without adjustment.1) To me, yes. They're a good basic meter with accuracy specs more often seen in a 6.5 digit unit. It's only let down by the lack of a current range lower than 200mA.2) Keithley 195, 197, 197A, HP 3468A, 3478A are the most obvious rivals, in that general capability/price range. Solartron 7150, if you like weird and quirky.3) Yes, it's well regarded; I've only seen positive feedback.

author: Slh
author_rank: Regular Contributor
timestamp: October 23, 2024, 06:38:38 am
content: I like my one. The main complaint I have about it is the length. It's not a serious issue but it's longer than the rest of my test equipment.

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 23, 2024, 11:36:20 am
content: As previous posters have said, the 8840A is a very nice meter. I especially like the rapid auto-ranging which seems to respond quicker than most other DMMs in that class.Other than the display, it is also relatively easy to fix. The most common problem seems to be cold solder joints on the main power transformer (it shakes itself loose on the main board).At least here in the USA, $100 is an OK price, nothing special. On eBay, there are many (8840A, not AF) up for sale currently in that price range.

author: BillyO
author_rank: Super Contributor
timestamp: October 23, 2024, 02:20:54 pm
content: Quote from: J-R on October 23, 2024, 03:15:12 amYes.Quote from: J-R on October 23, 2024, 03:15:12 amDon't know. Is there a way to check externally? I doubt I'll be able to take it apart.Quote from: J-R on October 23, 2024, 03:15:12 amNo GPIB.Quote from: J-R on October 23, 2024, 03:15:12 amYes, I have a modern meter (SDM3055). This will be a supplement to that.Quote from: J-R on October 23, 2024, 03:15:12 amI can be patient..

author: BillyO
author_rank: Super Contributor
timestamp: October 23, 2024, 02:22:28 pm
content: Thanks to everyone for their input. I appreciate it.

author: J-R
author_rank: Super Contributor
timestamp: October 24, 2024, 07:12:19 am
content: Quote from: BillyO on October 23, 2024, 02:20:54 pmYou should get error code 30 when selecting "V AC" if the option board is missing.

author: BillyO
author_rank: Super Contributor
timestamp: October 24, 2024, 01:28:57 pm
content: Quote from: J-R on October 24, 2024, 07:12:19 amGreat, I'll try that. Going to see it tomorrow. Thanks!

author: BillyO
author_rank: Super Contributor
timestamp: October 25, 2024, 07:59:16 pm
content: Well, I bought it. It does have the AC option and is not nearly a dim as I was led to believe.What is the IDC connector on the back panel? Also, does anyone have a link to the manual specific to this model?

author: bikeNomad
author_rank: Contributor
timestamp: October 25, 2024, 11:14:01 pm
content: Manual with schematics is here:https://dam-assets.fluke.com/s3fs-public/8840A___imeng0300.pdf?VersionId=fKpyqLs1kBQrNJNIoEVUEfhGMEyT9PD3AHOL's display is nice, though the words are smaller than in the original VFD.I have designed an add-on continuity buzzer board for this meter and have a few left I could sell (PM me).

author: GigaJoe
author_rank: Frequent Contributor
timestamp: October 26, 2024, 09:51:26 pm
content: check a current range if it OK , one of my had it blown, and tracing going far to under metal cap on board .. ( not a fuse ... somewhere deeper )most likely PSU caps gone, anyway not bad to replace it, ( any el. cap to replace) you may see flippin LSD on lowest range. (not remember AC input filter caps but not bad idea to replace as well )bottom line for 8040 around 50 + shipping; 100 ok for a good conditionAHOL digits smaller but brighter , and blue, quiite better under bright light , my probably initial design , probably it was redesigned a bit , but wouldn't replace it if original ok

author: BillyO
author_rank: Super Contributor
timestamp: October 27, 2024, 12:57:59 am
content: Here it is in it's new home. After being on for 28 hours, the display is actually quite good.It passes the internal testes. It also matches my Siglent SDM3055 in all tested functions and ranges to within a couple of counts. For some reason their firm agreement gives me confidence in both of them.One strange thing is the 8840 holds the voltage last read (at least in DC) to within .1% for over 24 hours! I've never seen this before.

author: BillyO
author_rank: Super Contributor
timestamp: October 27, 2024, 12:59:36 am
content: Thanks to everyone for their input!

author: J-R
author_rank: Super Contributor
timestamp: October 27, 2024, 03:06:36 am
content: The lower three DCV ranges on the 8840A have an input resistance of greater than 10G Ohms, so that is probably why the reading hangs around so long.That connector should be the end of the ribbon cable for the GPIB option board.