Schematic of a dual 30V - 5A PSU clone - Page 1
Forum section: electronics / repair

author: slash14
author_rank: Newbie
timestamp: October 26, 2014, 09:49:02 am
content: Hi everyone,I'm the owner of one of these Chinese bench power supply clones.Mine works quiet well (although I did no took the time to check in details) but I'm pretty sure this unit will fail, one day or another.In order to anticipate such failure, I'm looking for the schematic of this PSU.EDIT: if you just need the schematic, the following one is reeeaally close. But I would advise to read the entire post for subtleties.https://www.velleman.eu/downloads/2/ps23023gbnlfresd.pdfI did try to find it by myself but did not succeed.The model of mine is named UG6010 (can't remember the brand), as depicted below:It's nothing more than a dual 30V, 5A PSU (with a 3rd 5V output), and it exists under the following references (and I may miss other references in the list):- Atten APS3005S-3D (this reference is actually mentionned in my user manual. Guess what: they did not properly changed the unit reference in my manual, probably taken from the Atten manual).- CSI 3005EIIIAs an alternative, I did find some schematics for this kind of PSU, but not for that precise model (although I'm pretty sure that all these clones share similar designs). For instance, the Mastech HY3020:Best regards.

author: Psi
author_rank: Super Contributor
timestamp: October 26, 2014, 10:49:43 am
content: The GW instek GPS-3303 has a similar look too.

author: Andy Watson
author_rank: Super Contributor
timestamp: October 26, 2014, 11:19:32 am
content: It bears a good resemblance to the power supplies mentioned in this thread:https://www.eevblog.com/forum/repair/tracking-problem-in-a-dual-bench-power-supply/

author: slash14
author_rank: Newbie
timestamp: October 26, 2014, 04:29:35 pm
content: Thanks guys.As I said: many clones exist for this kind of PSU.The link toward the P23023 from Velleman is quite interesting:- As far as I understand from the code name, it is supposed to be a dual 30V, dual 3A PSU. And it is actually confirmed by the user manual. So it's pretty close to my model.- In the user manual, there is a schematic (for once !). Seems that the 5V output is missing (however, I may simply have missed it), but definitely a good place to start.I'll tear my PSU down next week to compare.Best regards.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: October 27, 2014, 08:24:44 am
content: QuoteThe 5V section is a separate unit, with separate transformer and regulator.See also the associated posthttps://www.eevblog.com/forum/repair/tuning-a-ps23023-power-supply/Jacques

author: macboy
author_rank: Super Contributor
timestamp: October 28, 2014, 04:35:30 pm
content: Quote from: JacquesBBB on October 27, 2014, 08:24:44 amMine has a fault in the 5V section, but I have never found a schematic for that. Do you have one?

author: slash14
author_rank: Newbie
timestamp: November 01, 2014, 01:30:52 pm
content: Hi everyone,Time to post some pictures ! Here they are.As you can see, wiring is pretty messy.Some heatshrinks have not even been heated and are moving along the wires ...Voltage and Amp meters board:Main boards:Power transistors:Anyway, the good news is: although I did not took the time to fully compare each component of my PSU to the Velleman one, the schematic from the Velleman power supply is probably THE schematic for mine (and many other clones I guess).I sampled a few components for comparison with the schematic, and there are only minor variations in some components numbers: for instance mine has V6 = Zener 6.5V and R2 = 1k, while the Velleman is V6 = Zener 6.2V and R2 = 560. Not a big deal I guess.Other noticeable difference compared to mine: on the Velleman, R10 and R12 are 0.82ohm (for a 3A PSU), while mine is R10 and R12 = 0.5ohm (for a 5A PSU).I guess with R10 and R12 = 0.25, we may end up with a 10A PSU, but power dissipation of transistors shall be checked prior to do this mod. I don't know either if the Ampmeter are properly setup for higher amps.Details not shown on the Velleman schematic: my PSU is fitted with 2 XFMR, one for each main channels.One of these, two separate secondary coils power the voltage and ampmeters of each channel.The other XFMR is used to generate the fixed 5V output, thanks to a 10.8V secondary output coil.The bridge rectifier, hidden below the wires:And this small PCB for the regulation:@macboy: I don't have the schematic for the +5V fixed output, nor I will have time to reverse engineer the PCB. However, I did my best with pictures so you can try to reverse engineer this part of the PSU. There are not many components so by checking them one by one, you'll quickly find which is the failed one.It might not be obvious but some solders are pretty ugly.For Folks on this forum who speaks Italian, here's a copy of the manual of my PSU.http://www.dimelweb.com/store/Manuali/ManualeAlimentatoreDuale.pdfPages 6 to 9 seem to be quite interesting as they describe in detail how the PSU works. However, I do not speak Italian at all so it might be full garbage. Anyway, with the support of the Velleman schematic, it will be much easier to understand how this PSU works.And for modder, new mods might emerge ...@3roomlab: as far as I checked, I do not have any thermistors, fans are always running. They are powered from the +12VDC, at the ouput of N3 (see schematic).