How to calibrate Siglent SPD1000X / SPD3303X / SPD3303X-E series power supplies?

[mawyatt]

Update, I've tried your procedure over 5 times without any change in the CH1 and 2 Offset Current limit. Tried using NI and EasyPower over Ethernet and no luck, nothing seems to remove this current offset. Tried using *CALCLS 8 (supposed to erase all calibration coefficients and set all channels to default values) a few times as well, same result 

With what you've found with the cal procedure, and the problem we're having with this unit doesn't give one much confidence in using these supplies for lab type bench work, well at least they don't have any overshoot at turn On or Off

Anyway, thanks for the effort and hope no one else gets stuck with this type of Offset Current Limit issue

Best,

[BreakingOhmsLaw]

The issue with the current limit procedure in the manual is, that the unit actually has to be actively limiting the current during calibration. Depending on how screwed the calibration is, a low setting like 100mA (as the manual suggest) actually limits the unit to just a few mA because the DAC is basically alredady just outputting 0 Volt to the circuit.
If you choose a setting (like my 500mA / 2.5A recommendation) where the unit is actually actively limiting the current (so you see an actual current >200mA), then the formula for the correction factor has a chance of doing its job.  It needs two points on a straight line. If one of those points is on the 0-line (you'll measure something like 5mA), the calculated correction value is wrong.

[mawyatt]

Understand the linear fit, and how this should work. The basic problem is that the Current Offset can not be removed by any means, even using the *CALCLS 8 which should reset all channel parameters to default.

Nothing we've done has changed this base offset current. What this offset does is without anything connected (0 current) the Current Limit must be set to >120ma on CH1 and >90ma on CH2 for the supply to go into Constant Voltage mode because the zero output current "reading" is ~120ma CH1 and ~90ma CH2 without supplying any output current. If you supply an output current then the current reading is the mentioned offset plus the actual output current.

In use you must mentally subtract the base current offset from the supply reading and set the CC mode to a desired current limit + this offset. We've tried to correct this so many times with this supply that the EEPROMs are probably exceeding their number of write cycles, and spent countless hrs/days trying to correct this problem

Not sure if this is a unique supply problem, hardware failure, firmware failure, or built-in design flaw but up to now unrecoverable, and why I would not recommend anyone deviate from the calibration procedures.

Also extremely disappointed in that Siglent factory has ignored multiple requests for help, and not even a factory response. If one intends to do self calibration I would steer clear of these supplies until the factory decides to address the issues you've found since one might end up with another big and heavy brick like we now have

After these cal problems, I've become somewhat disillusioned with the SPD3303X-E and considering replacing the two "good" supplies with something more trustworthy. We have some very expensive developmental electronics powered from these supplies and a single hiccup or incorrect output setting or reading could destroy 10X the supply cost, so this is an Open Door for Mr Murphy to set in  

Anyway, thanks for looking into this calibration issue.

Best,

 

[BreakingOhmsLaw]

Okay, I understand your problem now. That's one sick puppy you have there.
I assume you have already tried this with the latest firmware (Release Date 02.05.21 ).

For company use, Siglent would not be high on my list of lab equipment solely for the lack of B2B sales. Nothing gets you support faster than a sales rep hell-bent on keeping you happy for your next order. We use R&S, Gossen Metrawatt and Delta Electronica.

Bob Pease's rule that the power supply should be the single most reliable piece of equpment in your lab still applies. If you look at old pictures from his bench, you'll only find top shelf PSUs ever. He even famously disencouraged engineers from building their own PSU, stating:
"Especially for a ‘hacker bench,’ you'll want a safe and reliable supply. A ‘hacker supply’ on a ‘hacker bench’ will just need fire-extinguishers."
Nothing to add there. Amen.

[mawyatt]

Very sick puppy indeed

Tried with 2.05 and 2.07 versions, same results.

I couldn't agree with Bob Pease anymore, folks that skimp on power supplies are just playing Russian Roulette with whatever they are working on. Murphy is just laughing and grinning

I've said this for many years that the single most important piece of equipment on your bench is your power supply. Exactly why I am concerned about these two other SDP3303X-E we have and are using, the third is this one with the current offset problem and will likely just become a paperweight 

Best,

[blurpy]

With Siglent trying to enter the pro marked, I wonder why they don't just fix this issue rather than risk the bad reputation and loss of future sales.

[mawyatt]

This is the worst product I've used from Siglent

The SDS2000X+ are stellar performers, the SAA3021X+ is very nice as is the SDG2042X, the SDM3065X and SDL1020X-E are OK, and these SDP3303X-E PSUs are at the bottom of the list. The UI is not well done with the "fine" button and arrow keys (usage makes no sense, frustrating, and potentially error prone), and why they placed the output jacks at non-standard spacing is inexcusable! However, the output voltage is clean and accurate (on two we have) without overshoot and these shortcomings can be overlooked which we've done in favor of a good, stable, clean, accurate output.

Now with the issues of self calibration and the ability to completely screw up the accuracy from a calibration mishap, which is evidently totally unrecoverable, and the lack of any factory response, even if negative, these PSUs are now considered "Buyer Beware" category. As attractive as these PSUs were from a price performance standpoint, these issues seriously take away from that perspective.

Siglent may be falling into the trap that has consumed so many others. They have a stellar SDS2000X+ product, other good products, but seem to be ignoring some lower level products/customers in favor of the movement into the "Pro" ranks. Classic example of forgetting who they are, why they got to where they are, and overstepping their bounds having to sacrifice factory present customer/product support to support the big step into the "Pro" ranks.

At least they are still paying attention to the SDS2000X+ as it's likely a cash cow, and need the income to support the "Pro" developments. Suspect engineering is way overstretched and no time to handle any support and/or present customer/products.

Siglent has introduced a new "Pro" level 2 and 4 port VNA (5000 series), new "Pro" level MSO (6000 series), and soon a new "Pro" level AWG (7000 series), all in less than a years span. That's way too many/much advanced product releases in such a short time frame for a company like Siglent IMO, likely severely straining the engineering/management side of the company.

Time will tell

Back to the PSU, are the GW Instek PSUs capable of self calibration?

Best,

[BreakingOhmsLaw]

Well, the one thing that makes it absolutely useless for any serious lab use is, that you CANNOT DISABLE the beep when it goes in to CC mode. WTF Siglent?

Helloooooo, Siglent? Anybody home?
Some people use CC continuously. As in ALL THE TIME.
For example to charge a battery.
Do I really need to open the unit and remove the bloody piezo beeper to shut the damn thing up?
Please someone tell me there's a secret button to make it stop.

[C.J.S.]

Well, the one thing that makes it absolutely useless for any serious lab use is, that you CANNOT DISABLE the beep when it goes in to CC mode. WTF Siglent?

In my experience the PSU only beeps when it goes in CC mode in combination with a very low output voltage. If you load the output of the PSU with a DMM in Ampere range connected to ground, you will get the beep. But if the output voltage is above a certain threshold voltage, the PSU does not beep. I don't know the exact threshold voltage, but I think it is below 1V. I expect that when using the PSU to charge batteries with the PSU in CC mode, it will not produce a beep.

[CDN_Torsten]

What beep?
The only time my unit beeps is during boot.

Operating in CC mode with Vout <<1V results in no beeping...

[CDN_Torsten]

The UI is not well done with the "fine" button and arrow keys (usage makes no sense, frustrating, and potentially error prone), and why they placed the output jacks at non-standard spacing is inexcusable!

The UI fine/arrow keys are the WORST implementation I have ever used.  It confuses me every time.  On what planet is this arrangement normal?
...and then there is the spacing of the output jacks.

[BreakingOhmsLaw]

Well, the one thing that makes it absolutely useless for any serious lab use is, that you CANNOT DISABLE the beep when it goes in to CC mode. WTF Siglent?

In my experience the PSU only beeps when it goes in CC mode in combination with a very low output voltage. If you load the output of the PSU with a DMM in Ampere range connected to ground, you will get the beep. But if the output voltage is above a certain threshold voltage, the PSU does not beep. I don't know the exact threshold voltage, but I think it is below 1V. I expect that when using the PSU to charge batteries with the PSU in CC mode, it will not produce a beep.

You are right. I was using an electronic load, and that obviously nearly short circuits it. On higher voltages it does not beep.
Still, this should be configurable IMHO.

[Bad_Driver]

I have to agree with all the negative feedback.
Now I own 5 Siglent devices and Santa Claus announced the arrival of an SSA3021X+ (thanks to SWMBO).

But I'm unhappy with the SPD3303X-E.
Yes, it produces DC, low noise and it has a hard power switch. But this is all positive what I see....

- the UI is a nightmare. (usage of arrow keys and "Fine" key and rotation knob)
- the weak binding posts are so cheap and unreliable
- the provided "software" looks like a DOS-program from the 90s
- the missing of an energy measurement function (mAs or Ah) - a simple multiplication!

still my both RIDEN 6018 have a much better user interface. 

Conclusion:  the SPD is heavily overpriced!
I'll keep it because it's paid with an not awaited small gratification from my employer as Amazon gift card.

[oz2cpu]

EXACTLY.. odd random low frequency regulation noise,
see more here :
https://youtu.be/BBW8dv2ImOc
and see that attached picture, when comparing to a dead cheap ebay psu

anyone figured out how to fix this ?

[Bad_Driver]

Hi oz2cpu,

I will try it, what load have you used? Open output, low R or SDL1020??

B.D.

[oz2cpu]

just open, no load, and about 2V since in this range my voltmeter got very high resolution, and can reveal the problem,
play with the time roll setting, and see how it looks
you got SDM 3055 ? or even better ?
I tried this many times, back and forward, just to prove it is not SDM 3055,
I constantly get the same result.
if any one will find the bug inside the psu, i will be happy to open and perform mod,
also we should inform siglent, so they can improve the design.

By the way : i got a few ideas for software improvements SPD3303X
in parallel mode : turn other screen off, and show the correct ADDED current, and the total power correctly..
today it display halve of the current and power in ch1 and the other halve in ch2

same problem in series mode !!
suggestion : turn ch2 display off.
and display the new total voltage, new total power..

I happen to use series and parallel mode a lot, so this not smart.

[Bad_Driver]

ok I own the SDM3065 but I‘m just starting  a business trip, so I can try it not before end of the week.

I found another benefit of the SPD, it is not as deep as the Rigol PSU and since I have very limited space
this was one of the main decision criteria.

B.D.

Edit:

I was curious about your findings and did a quick test.

First finding:
Standard deviation (noise) increases with load (ohmic resistor)

Second Finding:
My 40 year old east german anlog PSU has at 2 volts about 10 times lower noise than the SPD3303 !!
Photos will follow when I return.

I have a Low Noise Amplifier on the bench for this kind of measurements, around Xmas I can do a deeper dive into Siglents noise floor with FFT 

[Bad_Driver]

As promised here my measurements of the SPD3303X. See photos and read STD value.

#1 warming up
#2 no load
#3 4 ohms resistor (0.5 A)
#4 2 ohms resistor (1 A)
#5 my 40 years old east german analog PSU

But I‘m not sure that this is the whole story, I tried to see the noise on the scope but my bench setup seems to suffer from grounding problems, I catch a lot other noise. It needs further investigations.

[oz2cpu]

thanks alot, I think what you see, is the same i see
the SPD3303 got :
quite warm up time before stable (you did warm up your multimeter a few hrs before starting the SPD warm up test ? we need to be fair here.
two different types of ac noise
one sine wave shaped very slow (also visible on your curves)
and one sharpedged pulsed, much faster (also visible on your curves)
is it possible to lock ? the vertical scale on your SDM 3065 ?
so it is same as mine ? and same time scale too ?
I am getting ready reperform my tests, but first i run a 2hr SDM 3055 warm up, so we know it is the SPD we see..

if you want to prove the SDM is performing stable, take a 1.5V AA cell, set the centre, and min max points, same as what we do for psu tests.
I also got a real old analog psu. mine is only 35years old, i will also see its power up, and warm up time, just for fun,
its refferance might just be a normal zener diode

[oz2cpu]

more : i came up with those settings, for more fair and more controlled compares:

power on warm up, 5mV full scale, 1800 sec full scale
this is my right unit SPD3303X ch1

[oz2cpu]

here my 35 years old justy kit powersupply

power on warm up, 5mV full scale, 1800 sec full scale

so clearly much worse, when it come to power up time :-)

[oz2cpu]

short term stability

0.2mV full scale, 10 sec full scale is the best to see this..
this is my right unit SPD3303X ch1
I use the manual set low and hi, for 0.2mV full scale, this was i can compare the curve, fair

[oz2cpu]

my old psu :

short term stability

0.2mV full scale, 10 sec full scale

see this is alot more stable, free from short term noise :-)

[mawyatt]

Here's the GPP4323, then the SDP3303X-E (augmented to a 3303X) and a very old linear EMCO. All set to ~2V. Note the GPP (1st) and SDP (2nd) have a vertical span of 200uv on the SDM3065X, the EMCO (3rd) span is higher at 700uv and not as stable as the GPP or SDP.

Best,


Edit: Added SD (RMS) over a 5 min time span, GPP ~53uv, SPD ~31uv and EMCO ~76uv

[Bad_Driver]

Wow, so much information on the last Sunday before Xmas!

I have to prepare the upcoming weekend for my three children (and to setup a new XBOX X so far) and for my very old
parents too and 4 days in business as well  And I‘m the chief of the kitchen (and the related food shopping drives)

Let‘s see what I can repeat with your settings this week.

One remark (you see my findings in the SDM-thread):
The SDM3065 settles down in a view minutes compared to my HP 34401a, I’m pretty sure that the warming up
curve comes from the SPD3303 but I will double check this.

It makes sense to use TestController again for this, more post processing capabilities and easier overlay of different measurments. I need more free time for the bench!!!!!!