Playing with the Atten PPS3005S DC power supply - Page 1
Forum section: electronics / general

author: bobski
author_rank: Contributor
timestamp: June 25, 2011, 07:30:35 pm
content: I'm a noob here, but what the hey.I'm starting a thread since doing this in someone else's classifieds ad seemed a little inappropriate. I posted this yesterday and updated it a few mins ago:Quote from: bobski on June 25, 2011, 03:02:06 amSo next I'm going to try hooking it up to my AVR Dragon to check my theory on the fuse bits.

author: bobski
author_rank: Contributor
timestamp: June 25, 2011, 09:03:08 pm
content: Bingo.Unfortunately, the limiter operation still seems flakey.

author: saturation
author_rank: Super Contributor
timestamp: June 25, 2011, 09:10:57 pm
content: Good work! If we can get some of these Chinese test gear working properly, its does give you a bang for buck. Can you characterize the PSU for us in terms of its ripple and output stability?

author: bobski
author_rank: Contributor
timestamp: June 25, 2011, 11:05:11 pm
content: Quote from: saturation on June 25, 2011, 09:10:57 pmThere's does seem to be some kind of harmonics going on.The peaks hit about 8 mV at 15 us invervals, while the noise at the base is about 0.8 mV.How would you characterize stability? Output voltage drift over long periods?Quote from: BoredAtWork on June 25, 2011, 09:41:35 pmWell, If nothing else, it was in the wrong forum section. ^_^Quote from: BoredAtWork on June 25, 2011, 09:41:35 pmYeah, ok... I can see that. They would need temp sensors at board-level as well as the heat sink at the back. But still, variable speed would have been nice. Don't necessarily stop the fan, but merely spin it down so it isn't so noisy. So long as there's airflow, the heat sink temperature should suffice, as all the air flowing through the case has to pass around or through the sink on its way to the fan and out the back.Quote from: BoredAtWork on June 25, 2011, 09:41:35 pmI'm not sure. Since the surge-y behavior of the current limiter doesn't seem to have changed with the clock speed, I suspect it's just digitally controlling an analog loop.

author: bobski
author_rank: Contributor
timestamp: June 27, 2011, 04:46:26 am
content: Can anyone recommend some good,free(or close to it) diagraming software? I worked with multisim in school, but it's not exactly affordable for the hobbyist.I've got the basic AC-in to DC-out path of the analog board down on paper:That covers about 1/3 of the board's area. Another quarter is simple 5V and 12V supplies based on 7805 and 7812 linear regulators. This is starting to seem manageable. Not included on that scribble are various little circuit offshoots from the main traces, as well as whatever controls the big NPN transistors... It looks like a couple of daisy-chained transistor amps, but amplifying what I don't know. Expanding the diagram so it's actually useful is going to get messy, so I would prefer to transfer what I have to software and continue from there. Which leads back to my original question: Does anybody know some good diagraming software for the hobbyist?

author: bobski
author_rank: Contributor
timestamp: June 28, 2011, 03:56:36 am
content: Slowly sprawling...Turns out there's an unused 2-pin "Temp" connector (pins labeled B and W) on the analog board. I guess it goes with the offset threaded hole on the heat sink?

author: saturation
author_rank: Super Contributor
timestamp: June 28, 2011, 01:52:41 pm
content: I haven't given this much exercise as I use paper too:http://www.dz863.com/index.phpQuote from: bobski on June 27, 2011, 04:46:26 am

author: bobski
author_rank: Contributor
timestamp: July 01, 2011, 04:45:24 am
content: Alright... I think this covers all the bits on the analog board that play a role in output regulation. This doesn't include the 5V and 12V regulators (LM78xx linear), associated components, or anything else that might be on the board, like fan control. I just traced everything that seemed to have a role in controlling the big regulator section.Any thoughts/analysis would be appreciated.

author: bobski
author_rank: Contributor
timestamp: July 01, 2011, 05:45:19 am
content: The wiring and polarities are correct. D13 is a glass case diode, but I can't read the part number as it is facing the circuit board (as is the case with a good number of the diodes). Perhaps it's a zener? I'll check it out tomorrow, along with D8, D9 and D10. All the restlooklike regular rectifier diodes.

author: Richard W.
author_rank: Regular Contributor
timestamp: July 01, 2011, 07:52:13 pm
content: What happens when you set the output voltage close below the switching threshold of the transformer-coil-relay and then connect a high power load?What happens with the output voltage when you increase or decrease the voltage and the relay switches?I guess there are some nasty spikes...

author: bobski
author_rank: Contributor
timestamp: July 01, 2011, 08:59:38 pm
content: Turns out D13 was the only zener diode.

author: bobski
author_rank: Contributor
timestamp: July 03, 2011, 09:11:00 pm
content: Quote from: Richard W. on July 01, 2011, 07:52:13 pmMaybe. On the other hand, that's part of the A/C section, so it's swinging positive/negative at 60Hz. That line of capacitors after the rectifier might smooth out that hiccup just fine.

author: Richard W.
author_rank: Regular Contributor
timestamp: July 04, 2011, 03:41:55 pm
content: QuoteI don't know if 6600µF are enough in this case. I would have added more Cs for the relay thingy.But 5 amps, capacitive load, that doesn't sound like a "longlife" construction.I prefer a real, 100% analog lab-supply.

author: bobski
author_rank: Contributor
timestamp: July 09, 2011, 06:48:41 pm
content: I decided I should probably be a bit more scientific about my tinkering. After replacing a suspect filter cap on the internal 12V supply (appears to have a puncture on its blowout seam, but no evidence of electrolyte leakage) I put everything back together and set up a simple test rig for the current limiter. It's a 120 ohm resistor as a load in series with a 1 ohm resistor as a current shunt. I hooked up my oscilloscope across the shunt (scope ground on the supply's negative post, test point on the shunt's remaining lead). Since it's 1 ohm, volts across the shunt should equal the current through it.Anyway, I set the current limiter to 5mA and got the following when I close the power supply circuit:The yellow curve is with the supply set to 30V, magenta is 15V and cyan is 5V.Looks to me like in each case, it takes a full second for the limiter to get where it's going. The curve looks like capacitor discharge or maybe an averaging routine if the uC is playing an active roll. The flat top is interesting... I would like to know what's causing it.30V. Yellow @ 100 mA, magenta @ 50 mA, cyan @ 25 mA:

author: Miti
author_rank: Super Contributor
timestamp: August 21, 2011, 07:02:06 pm
content: Quote from: bobski on June 27, 2011, 04:46:26 amTry Eagle from Cadsoft. They have a free version with some limitations but is more than enough for most of a hobbyist needs.http://www.cadsoftusa.com/downloads/miti

author: Miti
author_rank: Super Contributor
timestamp: August 21, 2011, 08:29:16 pm
content: Quote from: Richard W. on July 04, 2011, 03:41:55 pm

author: Zero999
author_rank: Super Contributor
timestamp: August 22, 2011, 11:58:51 am
content: Quote from: Richard W. on July 01, 2011, 07:52:13 pmThat sort of tap changing scheme has been used for linear power supplies, long before MCUs were invented. It helps to save power and reduce the power dissipation and heatsinking requirements for the power transistors. There's nothing wrong with it as long as there's enough hysteresis to prevent oscillation and the power supply rejection and transient response needs to be good enough to suppress the spikes.Quote from: bobski on July 09, 2011, 06:48:41 pmThat's unacceptable, perhaps you should consider replacing all of the electrolytic capacitors? If they've used shitty capacitors throughout it's likely to cause problems later which could be time consuming and expensive to repair.QuoteIt probably is a capacitor discharging. For a start there's 940uF on the output of the regulator, the RC time cvonstant at 120R will be 112ms and there will probably be another RC delay in the current limiter circuit. Notice how the current limiter seems to kick in more quickly at higher voltages? This is because the current will be higher so the capacitor in the feedback loop will be charged more quickly.

author: bobski
author_rank: Contributor
timestamp: August 22, 2011, 12:56:18 pm
content: Hmm. So the verdict is that this supply's analog section suffers from over-filtering?

author: Zero999
author_rank: Super Contributor
timestamp: August 22, 2011, 06:31:03 pm
content: It's pretty normal to have this kind of time delay on the current limit. If it were instantaneous, you may complain about the voltage dipping under surge conditions such as those caused by a capacitor charging , large incandescent light turning on or a motor starting. Ideally, it'd be nice to have a PSU with a variable time delay on the current limit so it can safely be used for LEDs as well as motors.

author: Miti
author_rank: Super Contributor
timestamp: August 26, 2011, 03:24:08 am
content: Be very careful with this power supply, the firmware (and maybe the hardware) has a lot of glitches. Here are few that I've seen:- Press the V-set button and the current display blinks- Turned the knob to decrease the voltage and it went up- Press the V-set or the I-set (I don't remember) and the output turned on - very badAfter about a week of ownership I think that it is well overrated at 5A. The main concerns are the rectifying bridge and the shunt wire resistor. At 5A they get pretty hot and I don't think there's a lot of air flow in the area of the bridge.On the plus side though, it has an input for a temperature sensor and the fan goes to the logic board so it can be controlled but that part is not implemented in the FW.Anyone up to the challenge to write a new complete and more responsive FW?

author: JSnyder
author_rank: Contributor
timestamp: October 21, 2011, 02:58:36 am
content: With everybody posting up atten PS tear-downs, I figured I'd post up my findings/mods to this power supply. I think you have to buy these supply's with the knowledge that they do have issues and it's a project rather than a perfect product out of the box. Theres 2 versions of this power supply, old and new. The old ones have hot glue instead of yellow adhesive over all of the connectors, a hand wound current shunt wire, metal wire jumpers instead of 0 ohm resistors. The new has the aforementioned yellow adhesive, and a mechanically wound current shunt wire (more on this later).The first mod to this PS was to cut out the stamped metal fan guard and replace it with a proper chrome wire guard (PC) this increases airflow quite a bit in general. Second the very loud "Runda" "good quality fan"(printed right on it! lol) was replaced with a silent Enermax fan.The second mod was more involved, I recapped all of the large electrolytic caps with name brands. The three large input caps (after the rectifier) were originally 2200uf @63v they were replaced with 4700uf@63v Nichicon caps. All of the others were replaced with the same value Panasonic FM and FC series caps.I did the crystal mod from 8.00 to 16.00 Mhz as Bobski pioneered, unfortunately on this board it appears that atten has set the reset disable fuse, therefore I am unable to reprogram it.As Miti pointed out the bridge rectifier gets worryingly warm with nothing more than a dinky heat sink to keep it cool. I de-soldered it and relocated to the chassis as seen in a number of mastec PS's. Problem solved, barely gets warm.Also I think Bobski's issue with slow current limiting and slow/no updating of the voltage during CC mode stems from the current shunt wire, My supply showed the same behavior as bobski's with the hand wound shunt in place, when i replaced it with the newer machine wound shunt it updated the V display and switched to CC very quickly. Don't ask me why this works, it just did for me YMMV.I plan on integrating the pc control part of this supply in the future, I was able to track down the software, all I have to do is build the usb bridge with an FTDI chip.I did some tests to see about accuracy. The load was a 3w cree attached to aluminum angle run at 1A

author: saturation
author_rank: Super Contributor
timestamp: October 26, 2011, 03:07:20 pm
content: @ JSnyder, great mods. That's what its all about, save you the trouble of building from scratch and a few 'upgrades' will give you a decent PSU. From your post it reads you've done the homework of reviewing the other PSU build qualities on eevblog.

author: bobski
author_rank: Contributor
timestamp: October 26, 2011, 05:37:11 pm
content: I went ahead and did those cooling mods (quiet fan, proper grille, moved rectifier to bottom of chassis) and will play around with the caps next.Quote from: JSnyder on October 21, 2011, 02:58:36 amHmm. I wonder if there have been any changes to the uC code?Quote from: JSnyder on October 21, 2011, 02:58:36 amAny chance of getting a few measurements of the newer shunt? Wire diameter, diameter of the coils, coil spacing (wavelength)?Quote from: JSnyder on October 21, 2011, 02:58:36 amAny info on that?

author: JSnyder
author_rank: Contributor
timestamp: October 26, 2011, 06:32:21 pm
content: Quote from: saturation on October 26, 2011, 03:07:20 pmThanks, you hit the nail on the head, I purchased it after looking at a number of power supply reviews, and wanted the project of bringing it up to standards.Bobski:I found there is no difference in the actual boards between the two revisions, some of the parts changed however, jumper wires are swapped with 0 ohm resistors, new current shunt wire, new rotary encoder, different physical size caps, silkscreen on the back of the analog board. I went ahead and dumped the hex from the newer power supply's atmega88p, I don't know how useful it is in that form. I have no reason to believe that there is any change in fw though.I just find it odd that you had no problem flashing your "old" style PS with the new fuses, I had no problem flashing my "new" style PS, and my old style wont go into programming mode. I went so far as to hot air the atmega from the pre modified supply, I just can't bring myself to put it on the working board.shunt specs:37mm lead spacing~ 1mm diameter wire (I'm almost certain you could rewind the old one)~ 16 turns total~ 2mm between turns~ 5.5 to 6mm coil diametersoftware can be foundhttp://www.atten.com.cn/Article/IndexDown.aspx?ChannelId=2&G=3&classId=27click on the d/l symbol next to this one PPS3005S??the installer is in Chinese, however when starting the application you can change it to English.The software seems decent, I can't comment as I don't have the usb bridge built. I can tell you the the serial port on the power supply does spit out data.Having said that, Bobski is your location in your profile accurate? If so we probably don't live far from one another. Send me a pm if you want to see the current shunt in person.

author: JSnyder
author_rank: Contributor
timestamp: October 26, 2011, 07:05:06 pm
content: bobski here is some close ups of the shunt, Your going to need a 3-4mm or so former to wind it.I also took a vid of it switching to cc mode, can you confirm that this is better than what you have mentioned in the past? If so, I really do believe the new shunt should help.

author: maciej_333
author_rank: Contributor
timestamp: May 22, 2022, 01:01:45 pm
content: I remember that in this thread was available schematics of this power supply drawn by someone from this forum. Nowadays this files doesn't exists. Someone can upload it or show me where can I find it? I'm sorry for writing in such old thread but I really need schematic of this power supply.

author: bobski
author_rank: Contributor
timestamp: May 22, 2022, 05:03:30 pm
content: Dropbox balked at being used as a pic server years ago, and broke all their links. I updated my old posts with these newfangled upload-to-the-forum-server pics. Ah, the wonders of modern computing technology.