Author Topic: Rigol DHO0804 starts up with large, varying offset (bias) voltages  (Read 599 times)

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Offline devinwTopic starter

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Like the title says, when I power the unit up, the bias voltages on the channels is always different, especially channel 2. 2 has been anywhere from 100 to 250mV, and yesterday it was 800mV! I realize this is not a DMM, but 800mV seems simply outrageous for any oscilloscope. I realize I can enter in a bias voltage for each channel, but that doesn't help if it boots up to a different bias each time. Is there some internal cal it runs when starting up that is screwy?

Anyone else experience this? Or should I send this thing back?
 

Online Fungus

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Re: Rigol DHO0804 starts up with large, varying offset (bias) voltages
« Reply #1 on: November 08, 2024, 06:19:13 pm »
Have you run the calibration?
 

Offline devinwTopic starter

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Re: Rigol DHO0804 starts up with large, varying offset (bias) voltages
« Reply #2 on: November 08, 2024, 08:30:20 pm »
Have you run the calibration?

I just tried the self cal. After the cal, all channels were looking good with low offset. We'll see how it is on the next bootup.
 

Offline devinwTopic starter

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Re: Rigol DHO0804 starts up with large, varying offset (bias) voltages
« Reply #3 on: November 09, 2024, 06:46:49 pm »
I've had the unit powered on for a few minutes and CH1 is averaging about 4mV bias, and CH2 is 60mV. The 60mV one was under 1mV yesterday after self-cal and using it for a few hours. I think I'm sending this thing back unfortunately.
 

Online Fungus

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Re: Rigol DHO0804 starts up with large, varying offset (bias) voltages
« Reply #4 on: November 09, 2024, 07:31:03 pm »
You have to let it warm up, but... 60mV sounds like a lot to me after "a few minutes".

Does it go away with time?
 

Online TurboTom

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Re: Rigol DHO0804 starts up with large, varying offset (bias) voltages
« Reply #5 on: November 09, 2024, 11:38:04 pm »
At what input sensitivity settings are you observing the offsets?
« Last Edit: November 09, 2024, 11:52:46 pm by TurboTom »
 
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Online Fungus

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Re: Rigol DHO0804 starts up with large, varying offset (bias) voltages
« Reply #6 on: November 10, 2024, 07:09:30 am »
At what input sensitivity settings are you observing the offsets?

Good point! I assumed this was at high sensitivity but every time I assume I make an ass of myself.

60mV at 10v/div would be perfectly normal.

 


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