SOLD: (USA So Cal) Siglent SPD 3303X-E like new - Page 1
Forum section: electronics / general

author: mjgillen
author_rank: Contributor
timestamp: July 26, 2025, 05:31:31 pm
content: For Sale USA Southern CaliforniaI have a two year old barely used Siglent SPD 3303X-E that has been "upgraded" to display three digits (https://www.eevblog.com/forum/testgear/siglent-spd3303x-e-hi-resolution-output-unlock/).Asking $200 (current retail is $460). Local pickup San Diego area or ships on your dime.MichaelSOLD for $180 + shippping

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 19, 2025, 03:18:00 pm
content: Hello,The Lab PSU arrived safe and sound, but it has a few problems...The most disturbing problem is parallel operation. The channels don't appear to connect properly. The voltage is also wrong by >120mV (which is way out of spec). My 6-1/2 digit DMM is within it's calibration period.The series mode lists the voltage range from 0-64v, but I can only get 0-60v. Looping gif attached.When you enable the output, you get this weird spike thing that Dave recently encountered, using a different function, on a cheap UNI-T switching PSU. I show this both under load and under no load. I also tested the timer function at 1s intervals with a rising voltage of 1v, just like Dave did in the aforementioned video, and I'm getting random length steps instead of 1 second between steps. Pictures attached.Here's the TE page for the PSU, which lists Ripple and Noise at <1mVrms.https://www.tequipment.net/Siglent/SPD3303X-E/DC-Power-Supplies/Lab-Power-Supplies/I measured the noise using a 1x probe and high-res mode of my MSO5000 scope (20M BW limit -- they used 1Mhz), both using P-to-P and V-Per-RMS (I think V-per-RMS is the correct setting), and got >13mV-Per-RMS and 110mVpp. I'm seeing notable spikes at ~120hz. I have also attached an image of the noise my probe picks up from normal, not connected, operation. Pictures attached.This is parts quality, not used and working. I'd like to get a return + refund or refund.Thanks!

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 19, 2025, 03:18:59 pm
content: Some images did not attach.

author: mjgillen
author_rank: Contributor
timestamp: August 19, 2025, 05:11:29 pm
content: Who is Dave?

author: bdunham7
author_rank: Super Contributor
timestamp: August 19, 2025, 06:53:58 pm
content: Quote from: ballsystemlord on August 19, 2025, 03:18:00 pmIf the seller evaporates you might be able to get warranty service.https://siglentna.com/service-and-support/warranty-information/

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 19, 2025, 08:20:46 pm
content: Quote from: mjgillen on August 19, 2025, 05:11:29 pmHe's the guy who runs this place. EEVBlog Dave. Here's the video I reference.https://www.eevblog.com/2025/06/13/eevblog-1691-uni-t-udp6731-360w-bench-psu-review/

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 19, 2025, 08:23:05 pm
content: Quote from: bdunham7 on August 19, 2025, 06:53:58 pmI would, but the unit is 6 years old (2019 manufacture date).

author: mjgillen
author_rank: Contributor
timestamp: August 19, 2025, 09:32:26 pm
content: Purchased 3/15/2023 still within three year warranty period. I have the receipt from Jameco.Michael

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 19, 2025, 09:42:13 pm
content: I've sent my email address asking for a picture of the receipt so I can claim warranty.

author: mjgillen
author_rank: Contributor
timestamp: August 19, 2025, 10:16:15 pm
content: Copy of invoice sent. I'm happy to help you get this sorted out.Michael

author: bdunham7
author_rank: Super Contributor
timestamp: August 19, 2025, 11:11:07 pm
content: Quote from: ballsystemlord on August 19, 2025, 09:42:13 pmIDK if this is a possible issue, but you might want to consider downgrading it back to the correct firmware. IDK for sure, perhaps others that have done thehackupgrade can chime in. It is is hard for me to imagine what defect might cause the variety pack of issues you are seeing.

author: J-R
author_rank: Super Contributor
timestamp: August 19, 2025, 11:29:45 pm
content: Manual states 60V maximum in series mode.No external sense, so the 120mV difference could be expected with such high currents.Ripple/noise is listed as 1mV RMS, but the regulation is 0.01%+3mV.What is the issue in parallel mode?

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 19, 2025, 11:55:41 pm
content: Quote from: J-R on August 19, 2025, 11:29:45 pmI literally posted a picture of the physical manual the instrument came with, and it says 64v.Quote from: J-R on August 19, 2025, 11:29:45 pmIf you look at the image, I'm using 3-wire setup for reading the voltage. Correct me if I'm wrong, but that should negate the resistance problem.Quote from: J-R on August 19, 2025, 11:29:45 pm(0.303*0.99)-0.003=0.29697v I'm seeing 0.183328v.Quote from: J-R on August 19, 2025, 11:29:45 pmAre you trying to troll me? Can't you see from the photos that I'm setup for 6.4a parallel output but I'm only getting 2.625a? Anything more than that and I get the red blinking light and a buzzer telling me I'm over loading BOTH stages.

author: J-R
author_rank: Super Contributor
timestamp: August 20, 2025, 12:36:59 am
content: I don't troll.Current datasheet and manual from Siglent both state 60V maximum in series mode. So they have changed their minds at some point.The photo you posted shows 0.300V maximum, and the supply is in CV mode. So that is why I asked what the issue was. It wasn't apparent. If you're getting the error and beep, you could be hitting the OCP setting. Maybe double-check that by long pressing the right arrow?I still think without an external sense feature the voltage reading could be quite a bit off at the higher current levels. Further testing/research warranted?For the noise/ripple, they do state 1MHz, but also I wasn't sure what voltage level you were testing at, so was just pointing out the regulation specs. What AC voltage do you get when measuring the output with a typical DMM?

author: thm_w
author_rank: Super Contributor
timestamp: August 20, 2025, 12:46:52 am
content: Simple way to check would be set channels independent mode, to 32V, no?

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 20, 2025, 12:50:31 am
content: Quote from: ballsystemlord on August 19, 2025, 11:55:41 pmI tested again using 2 meters. You're correct. The 3-wire setup is insufficient. I'm getting 60mV difference between the two worst case scenario. Around 20mV otherwise.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 20, 2025, 12:53:43 am
content: Quote from: thm_w on August 20, 2025, 12:46:52 amThe independent channels do go to 32v. Well, except channel 3.

author: 44kgk1lkf6u
author_rank: Regular Contributor
timestamp: August 20, 2025, 01:40:26 am
content: The seller addressed some problems. I want to address the other problems.The problem with the steps being of different duration seem to be a problem with the design of the firmware. You can't blame the seller. But maybe you can convince the manufacturer that the device is poorly designed to get a refund. Last time I used one of these power supplies the firmware seemed to iterate at an interval of a submultiple of 500 ms. So maybe the firmware's time step and the requested time step aliased.I don't understand why there is a peak when the supply turns on. Did you happen to have parallel mode turned on? What were the voltage and current set to?You should take into account the DC offset of the oscilloscope when measuring the noise. Run signal path compensation if you don't remember when you last ran it. You also need to limit the bandwidth. You can limit the bandwidth by using high resolution mode on the oscilloscope and setting the sampling rate to about twice the bandwidth you need.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 20, 2025, 01:44:03 am
content: Quote from: J-R on August 20, 2025, 12:36:59 amI connected up a 12v 4a server fan. It's the heaviest high-current load I have. IDK how it will affect the readings. I got >9mv AC RMS voltage with my GW Instek 9061 DMM. It's rated for 300khz AC RMS voltage reading. I also tested with my BK Precision 391A which is rated for 2kHz. I got >5mV AC RMS. I did not wait one hour, as I had done in my previous measurements, for the instruments to reach operating temperature.Again, IDK how that big fan will affect the readings, but from what I see, I think it's safe to say that the AC RMS noise is out of spec.EDIT:44kg1lkf6u, I don't blame mjgillen (who sold it to me) for any of this. I don't think he had any idea about these things. It has a power-on-count and it was used only 12 times. I'm glad you explained the FW to me. That's a curious one. I can do more testing later.EDIT2: To be totally clear, unless someone intentionally broke an instrument, I find that the faults/problems with an instrument are the fault of the instrument and/or it's creators. Not the poor soul who bought it.

author: 44kgk1lkf6u
author_rank: Regular Contributor
timestamp: August 20, 2025, 02:43:50 am
content: A brushless DC motor has switching transistors inside. A brushed DC motor has switching contacts inside. They inject ripples to the power rail. Just as if the power supply is a switcher.Quote from: ballsystemlord on August 20, 2025, 01:44:03 amI don't like Siglent either.

author: bdunham7
author_rank: Super Contributor
timestamp: August 20, 2025, 03:10:49 am
content: Quote from: ballsystemlord on August 19, 2025, 03:18:00 pmAfterJ-R's comments I looked at your photos and I have to agree that you simply aren't doing that measurement correctly. You're running the entire 2.6A through that negative (common) lead and that could be the source of 120mV drop.Also, you need to use a plain resistor for the load when you do the noise measurement if you want to get the right reading. I have to say this unit is looking less broken as we go along here.QuoteBut the firmware has been upgraded and the newer manuals say 60V so it's pretty clear what happened there.QuoteAccording to what I'm seeing in the one photo you have the voltage set to 0.300V and that is limiting it. Set to voltage to 2V and show what happens. Also, before using the parallel connection mode test the maximum outputs of both channels separately, both at the same time if you have the equipment for it.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 20, 2025, 04:14:18 am
content: Quote from: bdunham7 on August 20, 2025, 03:10:49 amUmm, isn't that what's inside of my DMM's 10a port? Just a plain resistor and a fuse?

author: bdunham7
author_rank: Super Contributor
timestamp: August 20, 2025, 04:42:37 am
content: Quote from: ballsystemlord on August 20, 2025, 04:14:18 amDidn't I read that you were using a server fan as your load?https://www.eevblog.com/2014/03/21/eevblog-594-how-to-measure-power-supply-ripple-noise/It wouldn't shock me to see the unit not meet its noise and ripple specs under very high load or corner cases like high load and very low voltage.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: August 20, 2025, 12:32:06 pm
content: Quote from: bdunham7 on August 20, 2025, 04:42:37 amFor my initial tests, using an oscilloscope, I was using just my DMM.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 20, 2025, 06:59:07 pm
content: The insufficient max levels issue was one reason they replaced the board on my SPD3303X. As I mentioned in PM, you should be discussing this with Siglent. They will take care of you, especially since it's still under warranty.Thanks,Josh

author: J-R
author_rank: Super Contributor
timestamp: August 22, 2025, 09:26:31 am
content: Quote from: KungFuJosh on August 20, 2025, 06:59:07 pmTo clarify, are you referring to not being able to exceed the current output rating of one channel while in parallel mode? Or something else?

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 22, 2025, 02:51:57 pm
content: Quote from: J-R on August 22, 2025, 09:26:31 amThis is copied from my RMA form last year:QuoteAfter receiving the repaired unit, it exceeded 6.42A.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: September 24, 2025, 03:45:49 am
content: Update:I ended up not sending in my Linear PSU.I don't think it's broken, I think that it's just a very "unique" instrument (and it needs calibrating). I intend to post a YT video about it at some point in time (I shot the footage, I just have to edit and upload.) I'll post a link here when I do.Thanks again to Mr Mjgillen for it!

author: mjgillen
author_rank: Contributor
timestamp: September 24, 2025, 03:48:21 am
content: You’re welcome. Glad it worked out.Michael