Rigol DL3000 Zero Resistance - Page 1
Forum section: electronics / repair

author: The_Gecko
author_rank: Newbie
timestamp: June 04, 2025, 10:17:56 pm
content: I have a Rigol DL3021A sitting in front of me. It's worked without any major issues for several years. Now that it is well outside of the warranty period, it decided to always have zero resistance at the input terminals. The result is that when you have a battery or power supply connected it looks like a dead short. There was no bang, no magic smoke, no power spike that hit other electronics in my house. I was using it and it just decided to behave this way. Pressing the SHORT button does nothing. Disabling the SHORT button in the Utility menu has no effect. Selecting between CC, CV, CR, and CP and pressing the ON/OFF button has no effect on the input terminal resistance.It powers up fine. No error messages on screen. No odd blinking LEDs. When the unit is powered off, a multimeter across the input terminals shows 370K ohms. Once the power button has been pushed, the input terminal resistance drops to 0.3 ohms and stays there. ...And when I said "Once the power button has been pushed...", I mean before the self test has started, before the white dots appear underneath "RIGOL", and before the LCDeven powers up.The fan spins up shortly after the unit is powered up, even without a power source attached to the input terminals. Based upon the fan volume, it's not spinning slowly.Thinking that this could be a weird firmware issue, I've attempted to kick it free by...Performing a reset from the Utility menuUpdating the firmware to 00.01.05.00.01, then performing a resetI also popped open the unit to look for any burned, blackened components, but everything looks pristine.I contacted RIGOL about my repair options. In short, I need to pay for shipping and pay a flat $200 repair fee. Their repair guy thinks it may be a 'failed digital board'. Therefore, I wanted to check with you guys* to see if there was anything you wanted me to try before I ship it off for repair.* This is the all-inclusive form of "guys" because it is much shorter than typing "all makes and models of humans"

author: thm_w
author_rank: Super Contributor
timestamp: June 04, 2025, 11:18:04 pm
content: Did you measure the resistance across the load FETs inside? D to S. Then maybe the voltage on the gates.I don't see any relay on the output, so maybe they are OKhttps://www.youtube.com/watch?v=Tk_3rYKWIIg

author: electr_peter
author_rank: Unknown
timestamp: June 05, 2025, 05:27:12 pm
content: Quote from: The_Gecko on June 04, 2025, 10:17:56 pmFan spins up after start-up and remains constant at slow-medium pace, this is normal.What V/I reading does it show on display with load On/Off with something connected? Can you test with external current limiting PSU?

author: The_Gecko
author_rank: Newbie
timestamp: June 07, 2025, 02:21:32 am
content: Here is the the equipment with no load, no connections. The power supply was configured for 0.9V and told to provide up to it's full amps (5A). Click for a bigger picture.Here is the equipment with connections, but the DL's ON/OFF button is off. No current should be flowing, but there is. The power supply was providing almost two amps, not shown here.Immediately after the above photo, I turned the DL's ON/OFF button to on. No change in current flow, resistance, or change to any numbers on the DL's screen. Note that the DL is on CR mode and the resistance is set for 200 ohms.Close up of DL's screen. No change of configuration since above photo.In this photo, I changed the range from 15K ohms to 15 ohms. No change in current flow, resistance, or change to any measurement numbers on the DL's screen.THM_W, I want to get your FET measurements, but I'm sick as a dog right now and fine motor skills are shot. This stuff ^^^ was easy. Give me some time.

author: J-R
author_rank: Super Contributor
timestamp: June 07, 2025, 05:39:26 am
content: I've noticed on this unit that the voltage display is constantly updated, but the remaining values are calculated after about a 1 second delay. On yours, only the voltage ever has a value. So maybe there is something wrong with the 4-wire current shunt section, or the Rigol tech is on to something and it's the digital board. Maybe try wiggling it from the slot a little and re-seating it.A new DL3021A is $639, so $200 seems to be a reasonable path for obtaining a fully working unit again. Do you have to pay more for parts, or is it truly a flat $200 repair fee no matter what they have to replace?

author: electr_peter
author_rank: Unknown
timestamp: June 07, 2025, 08:22:46 am
content: 0A is displayed when load in turned ON (should show something in that case), could be something digital related.Few more things - try BNC voltage/current read-outs at the back just to be sure. Also, enable CV mode with V set to 0.1/0.2/0.3/0.5/1.0V in your current setup.

author: The_Gecko
author_rank: Newbie
timestamp: June 08, 2025, 01:26:18 am
content: I pulled and reseated the digital board. No improvement. I fiddled with CV mode and very low voltage settings, but that didn't make a difference.I'm going to have to ship this thing in for repair.