Author Topic: Rigol DP832 measures "ghost" current  (Read 1560 times)

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Offline Milentije

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Rigol DP832 measures "ghost" current
« on: May 23, 2015, 05:42:23 AM »
Hello to everyone!

My DP832 finally arrived 3 day ago. And, immediately after opening I had a problem. The fan was dead on arrival and I couldn't turn on any of the outputs. Because I didn't want to wait for another month, or even more, for RMA I opened the unit and replaced the fan. After that the power supply allowed me to turn the outputs. NICE, I thought.

BUT, now there is a new problem.



Problem is in channel 1 and 2, channel 3 works fine.

Problem appears when there is NO load on the channels 1 and 2. As you can see from the picture that I linked above, power supply reads the current of 50mA on channel 1 and 150mA on the channel 2. Problem stays there even if I set the current limit at any level higher than 50mA for CH1 and 150mA for CH2.
If I try to set the OCP for CH1 lower than 50mA, power supply turns that channel off because of OCP.
Same is happening if I set OCP at the value lower than 150mA for CH2.

Problem disappears when there is any kind of load. Even a single green LED with 1k resistor solves the problem (@ >3V). With that load readings are as expected on both channels.

What could be a reason for this?

Thanks in advance,
M.

EDIT: I apologize to moderators for opening a new thread but I couldn't find the right one to put this in.

EDIT 2: I forgot to mention this:



Problem disapperas on the CH 1 when the voltage is set to 20V or more, but there is no change on the CH 2 even if the voltage is set to 30V.
« Last Edit: May 23, 2015, 06:17:50 AM by Milentije »
 

Offline dadler

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Re: Rigol DP832 measures "ghost" current
« Reply #1 on: May 23, 2015, 06:30:53 AM »
I would send it back and get a new, fresh one.
 

Offline XFDDesign

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Re: Rigol DP832 measures "ghost" current
« Reply #2 on: May 23, 2015, 10:54:50 AM »
He decided to crack it open and void the warranty. He's rooted.

In all probability, from very limited information, I would guess this never go through QA/QC and Cal. The "ghost current" is likely an offset error that needs to be trimmed. Either way, it's probably a paperweight now, without more extensive work being performed.
 

Offline Skimask

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Re: Rigol DP832 measures "ghost" current
« Reply #3 on: May 23, 2015, 11:04:07 AM »
 |O
Or...search for that particular 'issue' here and find the solution.
I didn't take it apart.
I turned it on.

The only stupid question is, well, most of them...

Save a fuse...Blow an electrician.
 

Offline Milentije

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Re: Rigol DP832 measures "ghost" current
« Reply #4 on: May 23, 2015, 05:20:14 PM »
He decided to crack it open and void the warranty. He's rooted.

"Warranty void if broken" sticker is in one piece, and there is no evidence of opening (except this thread). :) So, there is no problem about that.

In all probability, from very limited information, I would guess this never go through QA/QC and Cal.

I think the same. I highly doubt about validity of cal. certificat.

The "ghost current" is likely an offset error that needs to be trimmed. Either way, it's probably a paperweight now, without more extensive work being performed.

It will be sent back.

Thank you all for your answers and help. It is going back.
« Last Edit: May 23, 2015, 10:00:37 PM by Milentije »
 


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