have ever you seen multimeter back light change the last counts on the display? - Page 1
Forum section: electronics / testgear

author: modz786
author_rank: Regular Contributor
timestamp: December 15, 2022, 04:19:47 pm
content: The culprit is a newly acquired OWON XDM1241.Anytime the backlight intensity is turned up from zero the last digits change by around 3 to 5 counts.Has anyone experienced the same with a factory stock multimeter of any brand?I emailed OWON and in two days responded with an exploration from the teckies and I wait to see.Perhaps I might be offered a firmware upgrade we shall see.

author: AVGresponding
author_rank: Super Contributor
timestamp: December 15, 2022, 05:59:40 pm
content: No, I haven't!I wonder if the vref is just the regulated supply for the meter logic ICs and dips a little when you load it up with the backlight?

author: Brumby
author_rank: Unknown
timestamp: December 15, 2022, 09:41:58 pm
content: That's not something I have encountered either - but I agree with AVG's suggestion that the voltage reference might not be as stable as you would hope. The other possibility being the higher current in the backlight circuit is being coupled to the measuring circuitry by some means - which, if it were the case, would suggest either a poor physical layout, a faulty component or a component not fitted properly.I am curious as to whether this phenomenon is better/worse at different ranges and is/isn't proportional to the measured quantity.

author: Kanbus
author_rank: Contributor
timestamp: December 15, 2022, 10:12:04 pm
content: Not the same but similar. My OWON B41T+ adds an extra degree when backlight turns on while measuring temperature. Turn on bluetooth and you go up one more degree. So logging temperature with any confidence is out of the question.The com terminal on the POS also broke recently.

author: modz786
author_rank: Regular Contributor
timestamp: December 16, 2022, 06:17:42 am
content: Now I have this quirk I will do some testing across all ranges over the week end.I agree the display power supply is taken NOT from its own regulator circuit more like an after thought but without the obvious wire soldered across the board.I bought the OWON out of curiosity and was on sale price with 0.05% DC and it takes up no real estate unlike my ancient Fluke 45OWON replied to me in two days and I wait for engineers assessment.

author: AVGresponding
author_rank: Super Contributor
timestamp: December 16, 2022, 06:24:39 am
content: Quote from: modz786 on December 16, 2022, 06:17:42 amIt might be possible to mod it to improve the situation, in this case. I'd bet even without the backlight issues it can't match the F45 for accuracy though...

author: modz786
author_rank: Regular Contributor
timestamp: December 16, 2022, 07:19:48 am
content: well I thought the same but a 5V reference (AD584JH) using masterprobes measured with Fluke 8846A reads 5.0002410v is Fluke 8854A 9.99933, OWON is 9.999 Fluke 45 9.99992.5v is Fluke 8846A 2.49674, OWON is 2.497 Fluke 45 2.4966OWON 5.0001Fluke 45 5.0000Fluke 45 I havent calibrated and its feathers aparts with 8846A and the OWON is not bad on DC accuracy BUT its accuracy is best with the BackLite OFF and the screen is very readable its really nice but Im still an old school fan for VFDs

author: modz786
author_rank: Regular Contributor
timestamp: December 16, 2022, 08:32:08 am
content: reply from owon...so if it falls within 5 counts it makes no difference what other factors affect the readings but they dont understand or refuse to acknowledge its hardly user trustworthy if you have to ask yourself what is the true reading when display light is on or off and the brightness options are 0, 25,50,75 100%

author: marks2c
author_rank: Contributor
timestamp: December 17, 2022, 03:56:41 am
content: XDM1241-U SN: 22400093Not seeing this effect on either ac or DC ranges, incl mV, when powered from the supplied 18650 batteries.

author: modz786
author_rank: Regular Contributor
timestamp: December 17, 2022, 06:26:08 am
content: interesting your sn is newer my sn 22190668.My version firmware is V3.3.1is yours the same?I brought in June 2022 from Banggood and after sales are a waste of time it tooks weeks for a reply that asked for a video, that was two weeks back.

author: AVGresponding
author_rank: Super Contributor
timestamp: December 17, 2022, 08:31:37 am
content: Quote from: modz786 on December 16, 2022, 08:32:08 am

author: modz786
author_rank: Regular Contributor
timestamp: December 17, 2022, 08:57:13 am
content: checked ohms, ACV, Temp no issues but another quirk of OWON is reverse the test lead polarity with back light on of off it gives different readings. Not even my various uni-t meters or other china brands I try and the Fluke45 just laughs at this carry on

author: marks2c
author_rank: Contributor
timestamp: December 19, 2022, 01:52:28 am
content: V3.8.0. Does not even vary by one count on mV DC.It is a tier-3 meter with a BA of 0.05%, DC-UPS that can be powered from 5V, all this while taking measurements and being controlled by SCPI. All for US$135 incl rapid international delivery. All in all: pretty darn good.That said, the meter should meet spec. My suspicion is that OWON addressed the issue (firmware and/or H/W fixes).

author: modz786
author_rank: Regular Contributor
timestamp: December 19, 2022, 06:43:55 am
content: yep snap good specs especially battery powered and or 5v USB C.I suspect a newer firmware is needed and have asked OWON to send me this.I gave up with Banggood and went to OWON direct.

author: marks2c
author_rank: Contributor
timestamp: January 24, 2023, 01:38:36 am
content: Did you have any luck with Owon direct?

author: modz786
author_rank: Regular Contributor
timestamp: January 24, 2023, 07:52:40 am
content: After this email they ignore my requests.So if a fault causes drift but its within their specs then its normal.So what do I do ? wait for this drift to pass outside specs then they do something? LOLI wouldn't buy OWON again after the poor customer service.A firmware upgrade sent via email may have helped but they dont respond.

author: modz786
author_rank: Regular Contributor
timestamp: January 24, 2023, 07:56:08 am
content: its the same count drift in any DC range. Resistance range not affectedI also tested with the unit on charge and no change.

author: AVGresponding
author_rank: Super Contributor
timestamp: January 24, 2023, 09:49:54 am
content: Have you had a look inside it, to see whether it might be possible to mod it to take the BL supply from the pre-reg part of the psu?

author: modz786
author_rank: Regular Contributor
timestamp: February 24, 2023, 06:00:43 am
content: A consideration for Easter break but I shouldn't be moding a under warranty meter and OWON completely no responsive to further requests for just a simple update for the firmware.Thanks

author: py-bb
author_rank: Regular Contributor
timestamp: February 24, 2023, 06:23:51 am
content: Yeah when the battery is low. This can't be helped. There will be a voltage it needs to work, below that it's not fair. The backlight uses a bit of power batteries drop voltage as you load them (the curve varies from battery to battery)So seriously don't hold it against itIfuckinglovemy Dialog PL280N which has a button and the backlight stays on until you press it again - I can leave it somewhere and watch itThere should be an icon on the display which indicates low battery.

author: Gerhard_dk4xp
author_rank: Frequent Contributor
timestamp: February 24, 2023, 06:48:01 am
content: I heard about a Tektronix sampling plug in where the trigger LEDaffected sampling time or amplitude. A few ps are much there.Gerhard

author: ironcurtain
author_rank: Regular Contributor
timestamp: May 27, 2024, 10:01:55 am
content: Did you ever manage to get any firmware update files from OWON?I have a newer revision but have not had the time (yet) to test if the drift is still present there. It makes sense that a low battery condition might trigger this. Does it happen if you leave it connected to a 5V DC source?

author: modz786
author_rank: Regular Contributor
timestamp: May 27, 2024, 10:22:46 am
content: Hi OWON is a waste of space, morons and talking with someone that does a lot testing of equipment told me his experience for tech support for donated and paid for out of his pocket that this is the case for not wanting to help they try to always blame operator error and refuse to possible software bugs or hardware issues.I dont remember if the problem persists with power connected for charging and to what degree if not the same when testing but I will try when I unpack as I moved recently.If anyone has received firmware from OWON perhaps they could share it on the forum Thanks

author: ironcurtain
author_rank: Regular Contributor
timestamp: May 27, 2024, 10:28:59 am
content: I will try to put some time aside to test mine, and look around for any firmware files.

author: modz786
author_rank: Regular Contributor
timestamp: May 27, 2024, 02:19:11 pm
content: OK unboxed just now and cold start we read following5v source (5.00024) in calibration fluke 8840 readingOWON in Auto Vambient room temp 25 CelsiusMid speed4.9995 backlight off4.9992 backlight 100%4.9993 backlight 50%after warm up 30 mins4.9990 backlight 0ff4.9987 backlight 100%4.9988 backlight 50%with and without 5v charge results same.Resistance ranges not affected by backlight

author: magic
author_rank: Super Contributor
timestamp: May 27, 2024, 03:09:19 pm
content: It's interesting that the reading decreases, which corresponds to increasing reference voltage, unlikely to be a result of power supply sag.Maybe the problem is that they failed at star grounding? Teardown time?

author: modz786
author_rank: Regular Contributor
timestamp: May 27, 2024, 03:16:59 pm
content: a previous reply had slightly newer firmware and no issues with reading discrepancy im sure its firmware related fix and wonder if any other owners have my issueshmmmm now second thoughts perhaps the reason they dont simply supply latest firmware is that its a hardware issues thats resolved on newer serials numbers now and they dont want to expose themselves ....poor star grounding layout perhaps

author: Muttley Snickers
author_rank: Unknown
timestamp: May 28, 2024, 09:22:52 am
content: Quote from: modz786 on May 27, 2024, 02:19:11 pmOut of curiosity I just ran the same test using an AD584KH reference on an XDM-2041 and it was rock solid without any fluctuation. Mind you it's a mains powered unit but they may share similar internals or architecture, I believe these use a Hycon HY3131 but I haven't opened it yet to check.

author: ironcurtain
author_rank: Regular Contributor
timestamp: May 28, 2024, 10:13:46 am
content: I have an AD584 reference board somewhere.I will check later, I don't think I have a suitable battery for it though.Will bring the details of my unit delivered this week, it should be "fresh stock".

author: modz786
author_rank: Regular Contributor
timestamp: May 28, 2024, 12:16:47 pm
content: a 9v battery should run it i use 4x1860 just because i only have a 4x battery container my ad584 just with input jack not spring battery mounts besides the input voltage should be above 4.5 voltsa UPS 12v battery has been used

author: ironcurtain
author_rank: Regular Contributor
timestamp: May 28, 2024, 03:48:45 pm
content: Done.My unit is running fw 4.2.0. S/N begins with 2405. Verified with DC power in and without, and different backlight settings.10v is spot on in any speed setting.7.5 gives 0.001 error margins2.5 gives 0.0005 error magins +/-5V gives 0.0012 error margins +/- (observed down to 0.0007).Using the probes that came with it.DC power in, when present, came from a relatively clean multi-port AC USB charger I have used for years (old Anker).All are "minus" differences (that is, the reading is that much below reference).Tested an eBay Aidetek VC97+ DMM I had close by, with much larger error margins immediately obvious.This is not lab testing you would be charged for... but to me it seems pretty spot on for the price range.I hope this helps other people.

author: modz786
author_rank: Regular Contributor
timestamp: February 19, 2025, 02:02:50 pm
content: Hey did you find any firmware files?I discovered the key sequence to get into debug mode for meter calibration so I thought to share with everyonePress following keys sequentiallyUTILITYMATHUP ARROWRANGEDOWN ARROWthen on screen select DEBUGwrite down what you see for a rainy day referenceyou can press RANGE to move the red pointer across to the Coef sectionDUAL will move along to the digit you want to change and use the ARROW keys for thisMATH is to save exit