Siglent SPD3303D review

[FrankBuss]

Just a short update: I've discussed the remaining problems with the very helpful Siglent support and after the fix the power on/off spikes are completely gone and the short circuit problem is solved for me, too.

5V short circuit test after the repair:


2.5V short circuit test after the repair:


I'll publish the repair instructions with the CAD screenshots as soon as I get the permission from Siglent.

[Hydrawerk]

Well, always buy a product that is in production for one year or so. Never buy a very new equipment with hardware bugs.

[FrankBuss]

Siglent permitted to publish their CAD screenshots, this is what they sent me:



The instructions:

a: add a transistor, model 2N3904(Thru-hole) or MMB3904(SMD), connected as the circuit shows
b: add a 1000pF capacitor, connected between pin 2 and pin 3 of JC1
c: change the ZD703 to the 3.3V zener diode 1N4728A
d: replace CC13 with a 100nF capacitor, in series with a 20k resistor

Step d was a bit complicated, but I managed it by soldering both parts upright at one side of each pad, and then connecting the top sides with a wire. The old CC13 was 100nF, too, so could be used for this step, if it survives the desoldering. I used a new one, just to be sure. 0805 works fine, but looks like the original parts are 0603, but I had already all passive parts in 0805. This is how it looks like:



Instead of soldering at JC1, which seems to be soldered to the board, I measured it with an ohm meter and looks like pin 2 of JC1 is connected to junction of the big 0.04 ohm current measure resistor at the bottom and the diode DC5, and to pin 1 of UC5 (the middle pin, bad numbering in the CAD diagram), which made it easier to repair, because I could solder the transistor and the new capacitor at the bottom and use just a wire for the other side of the new capacitor.

This didn't really fix the overshooting, but after some more communication with the support, I got another instruction: Change RC5 to 200 ohm:



I used 220 ohm, and now it looks (nearly) perfect:

Just to show the effect of the changes, before the repair:



and after the repair:



And the power-on/power-off spike is gone, too.

  for Siglent, now I can recommend this power supply without reservations. The support told me that these changes are already included in a new revision of the PSU, maybe ask them which version you get if you don't want to open it and fix it yourself

[Zbig]

I've fixed mine according to this description and I can confirm that CH3 problems are gone now. Great job, Frank!

[FrankBuss]

Looks neat with the heat shrink tubing and hot glue.

[Zbig]

I've just found a rather hilarious firmware bug. The developers apparently cut some corners and it looks like when you save a preset (you can store up to 5 of them) it actually just dumps the RAM image to non-volatile storage. The result is, when you restore a preset, the start-up counter gets restored as well I guess it's supposed to be an equivalent of a car's odometer so don't rely on it to much if you're planning on getting a second hand SPD3303 Mine's firmware version is 1.01.01.01.03R1 (now, that's a mouthful).

[FrankBuss]

Same in my version (I have firmware 1.01.01.01.05), it shows the start-up counter saved in the preset after restart.

But not very useful anyway. In a lab it could be started just 10 times, but running 24x7 for years, and a hobbyist could start it 200 times, but only for half an hour each time.

[Zbig]

Same in my version (I have firmware 1.01.01.01.05), it shows the start-up counter saved in the preset after restart.

But not very useful anyway. In a lab it could be started just 10 times, but running 24x7 for years, and a hobbyist could start it 200 times, but only for half an hour each time.

Exaclty, and it doesn't tell you what it's been through (powering an Arduino for whole its life or some heavy inductive loads?), either. I don't care much about it, just find it kind of funny

[FrankBuss]

Wold be interesting to take a look at the firmware, if you want to ask for a 1.01.01.01.05 firmware update file

[Zbig]

Wold be interesting to take a look at the firmware, if you want to ask for a 1.01.01.01.05 firmware update file

You mean ask Siglent support? Sure, why not, but I don't know their e-mail (never contacted them yet). Could you provide it, please?

[FrankBuss]

There is a "Customer Service" navigation on their webpage http://www.siglent.com/en , but looks like they screwed it up, at least in Firefox and Opera it is not click-able. Last time I just wrote to sales@siglent.com (the only eMail address I could find on their webpage) with the request to forward it to technical support.

[psycho0815]

it's clickable on chrome, but there's only links for msn-messenger and skype in the menu, no email. There is however an emailform on siglent.eu when you click on "contact us" right at the bottom of the page.

Personally i'd propably take the rigol over this one, but that's more of a gut thing than anything else.
Also, never heard anything bad about batronix (including own experiences), which is kind of a big point for me.

[Zbig]

My gut feeling was more towards Siglent and I'm very glad I made that decision. Have you seen the massive thread dedicated to problems with Rigol? Well, my Siglent had only some issues with CH3 which are now fixed. Comparing to the Rigol, Siglent has:

• Each of the three channels properly isolated from each other
• No power-on/off spikes of any kind on the main CH1 and CH2 from the get go
• Parallel and serial modes do actually make the connections internally with relays hence no need for a shorting bar (yes, it matters to me)
  

Anyway, are you sure that's really the gut feeling? Or is it because Siglent's PSU didn't get Dave's attention?

EDIT:
Oh, after reading some updates on the Rigol thread and how they "solved" the overheat issue: the fan on my Siglent is idling under no load conditions, I can barely hear it.

[psycho0815]

Nah, believe it or not, but dave's not a factor here.
The overheating issue with the rigol seems to be fixed. I don't think anyone has actually tested yet, whether or not the overshoot issue is still an present in the newest rev.
As for the siglent fix. I don't want to solder in some bodge myself. I want the manufacturer to fix it. So if i can find a retailer, who can guarantee to deliver the newest rev. without the issues than maybe.
Also:
I really don't like the fact that i can't set a current limit on the 5V channel. I know i can use ch1 or 2 at 5V but still. Just doesn't seem thought through.
Also i want a number pad. I like knobs as well as the next guy, but i like being able to just punch in a value, too. It's digital anyway so there's really no excuse. Especially for stuff like the timer it would be alot more convenient. Sure the keypadlayout on the rigol is ridiculous, but at least it has one.

All that said, a 3 channel psu is more of a want than a need for me anyway so maybe i just wait a couple months and revisit the market than to see if the newest revs. ironed out all the kinks on either unit. 

[Zbig]

Fair enough, the "auxiliary" nature of the CH3 and lack of the numerical keypad, while not being the issues for me personally, are perfectly valid points.

[jimjam]

Nah, believe it or not, but dave's not a factor here.
The overheating issue with the rigol seems to be fixed. I don't think anyone has actually tested yet, whether or not the overshoot issue is still an present in the newest rev.
As for the siglent fix. I don't want to solder in some bodge myself. I want the manufacturer to fix it. So if i can find a retailer, who can guarantee to deliver the newest rev. without the issues than maybe.
Also:
I really don't like the fact that i can't set a current limit on the 5V channel. I know i can use ch1 or 2 at 5V but still. Just doesn't seem thought through.
Also i want a number pad. I like knobs as well as the next guy, but i like being able to just punch in a value, too. It's digital anyway so there's really no excuse. Especially for stuff like the timer it would be alot more convenient. Sure the keypadlayout on the rigol is ridiculous, but at least it has one.

All that said, a 3 channel psu is more of a want than a need for me anyway so maybe i just wait a couple months and revisit the market than to see if the newest revs. ironed out all the kinks on either unit. 

So psycho, which power supply did you end up getting? And what do you think of it?

[ScottyAU]

Is there a revision of this guy now from siglent with the hardware changes mentioned in this thread included?

Cheers.

[FrankBuss]

Is there a revision of this guy now from siglent with the hardware changes mentioned in this thread included?

I don't know, maybe ask here again:
https://www.eevblog.com/forum/testgear/siglent-technical-support-join-in-eevblog/

[jimjam]

So to recap, before I ask the Siglent guy, the issues were:

- Spikes / overshoots on CH3 during power on / power off
- Spikes when the output of CH3 is shorted

Have I missed anything else?

[FrankBuss]

Right, these were the problems. And a minor usability problem: when setting the voltage, you can either adjust it in 1 V steps, or with the "fine" button in 0.01 V steps, but not in 0.1 V steps. Maybe they have a new firmware which fixes this (my firmware version: 1.01.01.01.05, hardware version: V1.1), I made some suggestions like pressing the fine button longer for 0.01 V and short for 0.1 V steps, because at least for my applications usually I need 0.1 V steps.

[jimjam]

Instead of pressing the button longer, perhaps it could be just a normal press to change the "cursor" position. Each time it's pressed, it would cycle through 1V, 0.1 and 0.01 (and 0.001 for the 3303S model)

[FrankBuss]

Right, cycling would be even better, because the same concept for both models. The current step size could be displayed on the graphics display.

[jimjam]

I really don't like the fact that i can't set a current limit on the 5V channel. I know i can use ch1 or 2 at 5V but still. Just doesn't seem thought through.

I just noticed this. Does CH3 have any short circuit protection?

[FrankBuss]

Yes, ch3 is limited to 3 A max. and short circuits are no problem.

[ScottyAU]

I've just ordered one from a local supplier here in Australia who says there stock is only a few weeks old.

Will post back when it arrives.