EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: unimorpheus on January 14, 2016, 06:38:30 am
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I just recently received (Jan. 2016) a Rigol DP832 Digital ver. 00.01.14.00.03, Analog ver. 03.02.04.03.02.04 and bootloader 01.09. I have noticed a strange readback problem on startup no load. I have searched the forum looking for a resolution and possible calibration fix but have not found anything specific to my problem. In short when I power the unit up and activate the channels I get:
No load everything zeroed.
CH1
show 10mV, 0A, OW
read 4.2mV, 2.25mA
CH2
show 2mV, 1mA, 0W
read 4.7mV, 2.63mA
CH3
show 2mV, 3mA, 0W
read 1.6mV, 0.85mA
Reading from a Fluke 87 (yeah, an original like new 87)
These errors will carry forward as input values are adjusted. I understand (to some degree) the limits of the unit accuracy but it just bugs me that I cannot set to unit to read zero at startup. The 1 or 2 mV hear or there is no big deal but the 10mV on CH1 really bugs me. Any way to fix?
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Hi,
The specifications claims the set voltage accuracy is 0.05%+20mV so if have an offset between set voltage (0V in this case) and "actually" voltage on the output (4.2mV in this case) of 4.2mV you're still well within its specification. The readback is specified to 0.05%+10mV so the 5.8mV difference between what the DP832 shows (10mV) and what you "actually" have (4.2mV) is also well within spec. It looks perfectly fine to me.
If you look at the first post in the DP832 Firmware Updates and Bug List (https://www.eevblog.com/forum/testgear/rigol-dp832-firmware-updates-and-bug-list/) thread you'll find links to documents describing how to calibrate it if you really feel you want/need to do that.
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Yeah I figured it was within spec, I just think it is strange that Rigol would offer a precision update that reveals the unit's accuracy limitations. Starting up with a 10mV reading error does not inspire a great deal of confidence. I will look at the calibration information you mentioned. Thank you.