Author Topic: have ever you seen multimeter back light change the last counts on the display?  (Read 4395 times)

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Online magic

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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?
 

Offline modz786Topic starter

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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 issues

hmmmm 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
« Last Edit: May 27, 2024, 03:24:58 pm by modz786 »
 

Offline Muttley Snickers

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OK unboxed just now and cold start we read following
5v source (5.00024) in calibration fluke 8840 reading
OWON in Auto V...ambient room temp 25 Celsius...Mid speed
4.9995 backlight off
4.9992 backlight 100%
4.9993 backlight 50%

after warm up 30 mins
4.9990 backlight  0ff
4.9987 backlight 100%
4.9988 backlight 50%
with and without 5v charge results same.
Resistance ranges not affected by backlight

Out 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.
 

Offline ironcurtain

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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".
"If you are going to fail, at least do so spectacularly."

Kurtz: [intercepted radio message] I watched a snail crawl along the edge of a straight razor. That's my dream; that's my nightmare. Crawling, slithering, along the edge of a straight razor... and surviving. -- Apocalypse Now (1979)
 

Offline modz786Topic starter

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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 volts
a UPS 12v battery has been used
 
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Offline ironcurtain

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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 margins
2.5 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.
"If you are going to fail, at least do so spectacularly."

Kurtz: [intercepted radio message] I watched a snail crawl along the edge of a straight razor. That's my dream; that's my nightmare. Crawling, slithering, along the edge of a straight razor... and surviving. -- Apocalypse Now (1979)
 


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