UNI-T UDB3000S Series: UDP3305S / UDP3305S-E

[audiotubes]

I just opened the box and I don't see any manual, just a calibration certificate from about a year ago.

Does a manual come with this device?

[thephil]

I'm not sure if I got a printed manual with my instrument. I usually misplace them anyway, so I prefer to have the PDF and throw away the paper manuals (unless they are really nice).
It's available for download on UNI-T's website.

[audiotubes]

Thanks, yeah I found there on the site. But I was susprised, since all my Siglent gear came with quite nice manuals.

[Pfriemler]

Can't still decide if the UNI-T 3305S-E or a OWON ODP3033/3063 fits better my "needs" (they have their pro & cons). Collecting arguments, I stumbled on the Digital IO panel on the UNI-T's back side. Did I miss any information on that? Neither Google nor the manual explain the pins. What are they for?

[thephil]

The interface on the back provides logic pins for external triggering (both to and from the PSU). There is a little bit of information in chapter 4.12 Trigger. I haven't used that feature, so far, so I can't really say much more about it.

[Pfriemler]

Got it, thx. 4x 3.3 volts logic lines - >3.3 may kill the device. Not a game changer for me.

[Pfriemler]

still struggeling between OWON ODP3063 (2x 30A 6A) and a UDP3305S-E.

some new questions...
Some firmware improvements are still undocumented. In Tony Albus' review I had a look at the zoom function.

And in the Utility menu there's a "Recorder" function...?
The OWON has a remarkable recording option for logging output values, 10k points with different intervals (1s up to ...?), you can log values to a .csv file on a USB stick, up to hours, and view them instantly on the PSU. The "WAVE" function of the UNI-T looks interesting, but without any settings there are only some curves, not more. Does the "Recorder" in the UNI-T provide anything like that?


And do we have any informations about the output capacity here? I do not like the 100µF (?) output capacity on the OWON, since it may kill components before the CC/OCP kicks in. With Phil's report in mind (he stressed a led with 20 mA CC for a hundred switch on/offs without any damage nor flashing LEDs): my (odd) Voltcraft has "only" 47µF. Once I had a linear Basetech BT-305 with >600 µF, horrible, sent it back.


Here are my pro-cons on both devices
OWON:
o I think, I do not really need the 1mV resolution of the UNI-T's non-E version. But OWON has it for less money
+ the OWON has no fan if unloaded. I do like the silence, thus I switch off my KORAD KA3005P asap :-)
+ It gives me 2 amps more in parallel mode. Maybe I will need that sometimes, my old has 10 amps
o There are the channel couplings that @thephil still miss. I am not sure if I will need them at all, but you will have 2 coupled but still independent channels unlike the UNI-T in series mode
+ I like the separate buttons to set voltage/current to each channel (with the UNI-T you have to select/change to the channel first)
+ on/off behaviour is excellent
+ USB host on the front
+ teardown looks quite good (see https://www.eevblog.com/forum/testgear/owon-odp6033-triple-power-supply-teardown/msg4573375/#msg4573375)
- they offer firmware updates for end users, but not for this model
- switching from independent to serial or parallel mode is not convenient ... several menu steps and external cables
- 100 µF output capacitors on each channel

UNI-T:
+ I like the GUI (much) more with clear readings, the still undocumented Zoom function looks great (eyes are getting worse :-)). And display softkeys are fine to me.
+ quick serial/parallel mode
++ one all-off/on button
+ rules (monitor) to switch off or warn (more flexible than OCP/OVP)
+ they fixed some issues and offer firmware updates to end users
- more "strange" behavior (some tooths in on-ramps)
- additional cable needed to use the USB host port at back side

aaaand my thx to thephil for the great blog reviews!

edit(2): some (more) corrections

[faktorqm]

Hi there, I did this comparison on an excel file about 3 months ago. Please see the attachment. Nice comparison BTW.

[BillyO]

Another thing you might consider is support.  UNI-T offer none.  And I'm not just exaggerating.  UNI-T do not have any support system whatsoever.

If you think I'm not correct, then I have a challenge for you.  Whatever country/region you are in try to find a warranty and or support service center, when you do post it here to help others.  I would love to be proven wrong.

But in the end it's your money. 

[pope]

Another thing you might consider is support.  UNI-T offer none.  And I'm not just exaggerating.  UNI-T do not have any support system whatsoever.

If you think I'm not correct, then I have a challenge for you.  Whatever country/region you are in try to find a warranty and or support service center, when you do post it here to help others.  I would love to be proven wrong.

But in the end it's your money.

Wow, I wasn't aware of that. Good to know. I don't think that's even legal.

[Pfriemler]

From a professional point of view, it's necessary to have a functional support to get back working equipment in a short time at reasonable costs, no doubts. This disqualifies UNI-T for such purposes, but so does OWON, am I right?

As a hobbyist, my preferences are different. My Voltcraft DPS2010 (a rather efficient 1.8-3V linear regulator powered by a regulated SPU, sold under many brands 20 years before) is bad in nearly all points (slow load regulation, horrible overshoots in cc->cv changes, fan control, ...), but beside the very special digital control board it's easy to maintain/repair, I have a full circuit diagram and parts are easy to get. Korad KA3005P with much better behavior, nearly full circuit, too. Of course there are no wiring diagrams from OWON and UNI-T, but neither do the so-called "Service Manuals" from Siglent.
Of course I took a Siglent SPD3303X(-E) into consideration. Buying an OWON or UNI-T, a RIGOL or even a SIGLENT is the same game of chance to mee, with only one difference:
How many are fixed meanwhile by users regarding spontaneous reboots due to an overheated bridge rectifier? There are YT tutorials about that. I do not see Siglent PSU as more reliable than OWON or UNI-T, I think it's more important to have a "critical mass" of experienced users to get educated hints how to fix them. And I'd rather fix my stuff myself instead of sinking half the price of a new unit into some more or less good support after the 2 years warranty is over. And from the hobbyist's point of view, I try to get the most for my money. This is not the case with Siglent. GWInstek, R&S out of reach.

[pope]

Yeah that's all interesting but at least in the EU there are laws that protect the buyer. One of them is a minimum 1-2-3 year (not sure) of warranty.

[pope]

Yeah that's all interesting but at least in the EU there are laws that protect the buyer. One of them is a minimum of 1-2-3 years (not sure) of warranty.

[Pfriemler]

Yeah that's all interesting but at least in the EU there are laws that protect the buyer.

During the first two years, it is the dealer's responsibility to ensure that the appliance is repaired (or mostly replaced if necessary), whereby I as the customer am obliged to prove that the defect existed from the outset after the first six months. In the case of internal manufacturing defects, this is not usually a problem.
After these two years have expired, you are completely on your own. And from the day of delivery, if you made the purchase somewhere overseas, which can quickly make the supposed bargain expensive.

The right to repair, including a right to get replacement parts for the end customer, is still under discussion in the European Union.

[pope]

UNI-T seem to have a european online store with the following info

+49(0)821 710 498 26
service-eu@uni-trend.com

So, there must be some sort of support otherwise it's illegal practise. At least that's my understanding.

[dreamcat4]

well lets assume for a second that the device DOES develop an internal defect at some point during it's lifetime. What would also be nice is to see some dissassembly / teardown photos. To see how easy these unit(s) are to repair. To know how easy or hard it would be to effect our own psu repairs. In the situation that such warranty or servicing is not actually available?

I suppose we don't see that [yet] because ATM new customers still has an intact and worthwhile warranties for the time being?

[pope]

I suppose we don't see that [yet] because ATM new customers still has an intact and worthwhile warranties for the time being?

... or they believe so (?) 

[Pfriemler]

well lets assume for a second that the device DOES develop an internal defect at some point during it's lifetime. What would also be nice is to see some dissassembly / teardown photos. To see how easy these unit(s) are to repair.

That's what I mentioned above with the "critical mass" of users. For Siglent and Rigol, there are lots of photos and videos, even Dave made teardowns and repairs here.

But I'd appreciate to return to the topic. Discussing the reasons if to buy more or less cheap equipment or not is a more generally problem. Here we are about the UNI-T PSU and their technical pro and cons. Thx.

[BillyO]

Wow, I wasn't aware of that. Good to know. I don't think that's even legal.

Not sure what it's like on your side of the pond, but here in Canada there are statutory warranties.  I believe it is a full year on new goods.  If the manufacturer does not have a means to handle the warranty claims, it falls back on the retailer.  If the retailer is off-shore all bets are off.  I think you might find it's pretty similar throughout the 1st world.  A good manufacturer will honor their equipment warranties regardless.  Korad is such a company.   They don't have a service center in North America, but will do everything they can to help you out.  UNI-T on the other hand will just ignore you.  I have personal experience with both of these companies.  A power supply from Korad and a Oscilloscope and a benchtop DMM.  I will never buy anything from UNI-T again that has a value over $50.  Both the UNI-T scope and DMM sit as reminders in the back of my basement, dead and abandoned by the company that made them.

Siglent and Rigol are in a different league.  Both have service centers around the world and offer great support.


Edit:
I notice UNI-T now have a location in NA and EU:

Uni-Trend Technology US INC.
3171 Mercer Ave Suite 104 Bellingham WA, 98225

Uni-Trend Technology EU GmbH
Affinger Str. 12, 86167, Augsburg (Munich area in Germany)


Well, maybe things have improved since the dark ages.  We need to get some success stories then.

Edit #2:
Just sent the NA location a general query.  We'll see if they respond.

[BillyO]

But I'd appreciate to return to the topic. Discussing the reasons if to buy more or less cheap equipment or not is a more generally problem. Here we are about the UNI-T PSU and their technical pro and cons. Thx.

Support is not a consideration?   

[dreamcat4]

But I'd appreciate to return to the topic. Discussing the reasons if to buy more or less cheap equipment or not is a more generally problem. Here we are about the UNI-T PSU and their technical pro and cons. Thx.

Support is not a consideration?   

He didn't say that and neither did i (the guy whom was responding to)....

How to put it more diplomatically? The effective real-terms value of the support depends on both the reliability and the repairability of the specific product. And i would much prefer to promote those goals within our society and amongst manufacturers than assume that it's so bad to the levels that support is both a necessary and critical element to the functioning of my item(s)!

Of course support is important, but not normally at the expense of the aforementioned thing(s). Unless in a minority of more exceptional circumstances. And certainly that is relevant for other types of product(s). But this is a PSU.

[Pfriemler]

Of course, it is good and valuable to know whether a manufacturer offers repair support or not. As far as UNI-T is concerned, the information here is actually spot on, thx to BillyO. And of course I like to buy only technical devices whose insides I have seen before. There are photos and/or videos for the OWON and UNI-T power supplies I mentioned, otherwise I wouldn't know that the OWON use two toriod transformers for each channel and the UNI-T- only one big (which, btw may be the reason why it is less weight). Both look well constructed and easy to disassemble.
The OWONs have been on the market long enough that there should be experience of possible faults and repairs, but there is none only one unsolved without any result (just found after I posted). This may be because they work almost perfectly, but it is more likely that the possibly few buyers do not make their problems public. Feedback even on new devices is very low to non-existent in this forum, and for the even newer UNI-Ts, the number of users known here can be counted on one two hand(s).

edit: I just went once again through the whole thread, with BillyO's support concerns at the second entry and Phil's report that he spoke to the (non existent?) support. Now I am a bit confused ...

still waiting for some news regarding the Recorder function, maybe I join the guinea pigs...

[thephil]

Quote from: Pfriemler on 2023-12-12, 19:51:36

And in the Utility menu there's a "Recorder" function...?
The OWON has a remarkable recording option for logging output values, 10k points with different intervals (1s up to ...?), you can log values to a .csv file on a USB stick, up to hours, and view them instantly on the PSU. The "WAVE" function of the UNI-T looks interesting, but without any settings there are only some curves, not more. Does the "Recorder" in the UNI-T provide anything like that?

So – I had a brief look at the RECORDER. It seems that you can have the PSU log data to internal memory or USB stick in pre-set intervals (minimum 1s). In the end, you get a `*.rec` file which is in an undocumented binary format.
It shouldn't be too hard to reverse engineer the format, but out of the box, I'm not sure what exactly you are supposed to do with it Maybe it can be opened in the Windows software and exported to a more useful format?

As far as I can tell, there is no way to recall and show these files directly on the instrument.

[Pfriemler]

@thephil, Thank you for checking, that helps a lot to decide for the UNI-T.
It's about what I was hoping for, but not quite.
A possible use case for me would be a charging process or the longer monitoring of a device with short-term malfunctions (dropouts, reboots). Ultimately, it is enough for me to view the data on the PC.
I was about to ask to post any kind of recording here (maybe with a short description what is recorded), but I do not see a way to get the PC software running without having the UNI-T connected ... 

[thephil]

I have written to UNI-T support asking for documentation of the REC files and hinted that a plain old CSV would have been better. Haven't heard back, yet.

However, the format is pretty simple, so I went ahead, did some reverse engineering and wrote a very basic converter.

https://github.com/philpagel/udp3305s

It's not complete yet, but it can already give you the voltage and current readout for the three channels as well as serial or parallel mode. There seems to be some more information in each record, but the converter should be usable for most purposes already.