EEVblog #440 - Atten PPS3205T-3S Triple Output Power Supply Teardown

• EEVblog #440 - Atten PPS3205T-3S Triple Output Power Supply Teardown
  Posted by mariush on 19 Mar, 2013 23:02
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• #1 Reply
  Posted by Thor-Arne on 19 Mar, 2013 23:05
• Sorry to hear about the camera trouble.
  And thanks a lot for redoing the shoot, much appreciated. 
• #2 Reply
  Posted by c4757p on 19 Mar, 2013 23:14
• His voice at the beginning talking about metal support rods, especially the words "although it's a hope", have a tone of pure despair.
• #3 Reply
  Posted by RobB on 19 Mar, 2013 23:16
• Dave, I hope you appreciate the irony in using your Atten hot air smd rework station to fix up some of the dodgy joints in the Atten PS 
  
  Thanks for the perseverance given the camera issues.
  
  Rob
• #4 Reply
  Posted by mariush on 19 Mar, 2013 23:16
• The quality of the boards is just... horrible.
  
  Yeah, give them credit for actually using connectors and gluing the cables but so ugly surface mount..
  
  The 10000uF capacitors are probably fake, the quality of the text is just bad.
  I saw some Aishi capacitors somewhere on the front panel which are low quality in general and the rest of the caps spread on boards are equally no-name  - I doubt they would have paid about 6-10$ a piece for those 10000uF capacitors
  
  Wouldn't it make more sense to turn the two boards 180 degrees and have the heatsinks at the sides of the case, with a lower speed/ more silent fans?
  
  This way each heatsink and fan would have clear path all the way to the front of the case and the board for the 6v output would also be less cooked.
  
  Not to mention the two boards could then be merged in the center and they'd save some money on the boards and some components like linear regulators that could be shared.
  
  I guess it costs too much to stamp another hole in the case and pay for a second fan, or something like that. I don't see any other reason...
• #5 Reply
  Posted by Psi on 19 Mar, 2013 23:49
• Hard to say what exactly happened with the files but i'm guessing the camera records onto a SDcard or similar.
  
  90% of the time those kind of problems are caused by failings in the fat32 filesystem, it's really prone to damage when not unplugged/unpowered gracefully.
  The real kicker is the damage doesn't always show up when it happens, it's not until later on (sometimes months later) when files begin corrupting.
  
• #6 Reply
  Posted by fpliuzzi on 19 Mar, 2013 23:51
• Another interesting video Dave. It looks that the negative lead of the 100uF, 16V capacitor at the 31:32 point in the video is unsoldered (unless it is just a weird black reflection in their shiny solder joint).
  
  Frank
  
  ps Maybe you could dump the video clips from the camera to your PC (if it is near you) at regular intervals so that you wouldn't lose too much footage if the camera gets wacky. I'm always having problems with corrupted thumb drives.
• #7 Reply
  Posted by LaurenceW on 19 Mar, 2013 23:57
• Dave, not my original quote, but here it is, just the same:
  
  "Technology" is simply stuff that doesn't quite work right, yet. There was a time when wheels were technology, but they've been debugged now.
  
  ATTEN you MUPPETS! You've very nearly got a good product here, but you've screwed up. Fix all the stuff Dave's told you about, and come back and tell us when you have.
• #8 Reply
  Posted by LaurenceW on 20 Mar, 2013 00:03
• I would think that the biggest parameter that a fake supply cap would not be able to match to the original would be it's Equivalent Series Resistance (ESR). Dave, if you have the strength, can you measure one or two of those "ChemiCons" <snigger>
  
  To measure a "true" heatsink temp with a non-contact IR device, simply stick a 25mm square piece of black insulating tape on the heatsink, and measure that. Works for me.
• #9 Reply
  Posted by David_AVD on 20 Mar, 2013 00:09
• Interesting that the SIL pad for the 5V series pass transistor also has heatsink compound on it.
  
  I was always under the impression that you shouldn't use compound in conjunction with a SIL pad.  All it does is add thickness and impede the thermal transfer.
• #10 Reply
  Posted by justanothercanuck on 20 Mar, 2013 00:42
• Quote from: David_AVD on 20 Mar, 2013 00:09

  Interesting that the SIL pad for the 5V series pass transistor also has heatsink compound on it.
  
  I was always under the impression that you shouldn't use compound in conjunction with a SIL pad.  All it does is add thickness and impede the thermal transfer.
  

  
  Is the SIL pad even worth using?  Since the transistor is screwed to the heatsink, it's still got the screw to conduct through...? 
• #11 Reply
  Posted by poodyp on 20 Mar, 2013 00:47
• There're likely bushings on the screw to prevent contact. 
• #12 Reply
  Posted by IvoS on 20 Mar, 2013 00:58
• Yep. Those caps are fake big time.
• #13 Reply
  Posted by David_AVD on 20 Mar, 2013 01:15
• Quote from: justanothercanuck on 20 Mar, 2013 00:42

  Quote from: David_AVD on 20 Mar, 2013 00:09

  Interesting that the SIL pad for the 5V series pass transistor also has heatsink compound on it.
  
  I was always under the impression that you shouldn't use compound in conjunction with a SIL pad.  All it does is add thickness and impede the thermal transfer.
  

  
  Is the SIL pad even worth using?  Since the transistor is screwed to the heatsink, it's still got the screw to conduct through...? 
  

  
  The SIL pad provides the insulation for the metal backing of the transistor.  The hole in that particular package is insulated.  Photo of 2 pin version attached.
  
  

  ---

  
• #14 Reply
  Posted by Dave on 20 Mar, 2013 02:28
• I was REALLY hoping you would disassemble the bloody thing and remove that damn eyelash from the display. Seeing it irritates me.
• #15 Reply
  Posted by amspire on 20 Mar, 2013 03:16
• Quote from: LaurenceW on 20 Mar, 2013 00:03

  To measure a "true" heatsink temp with a non-contact IR device, simply stick a 25mm square piece of black insulating tape on the heatsink, and measure that. Works for me.
  

  I was thinking the same thing watching the video. Doesn't even have to be black tape - any colour electrician's tape works as well, or even paper-based masking tape. They are all black at the IR frequencies the temp meter works at. Kapton tape is probably better. Even a black waterproof marking pen does a good job.
• #16 Reply
  Posted by Lightages on 20 Mar, 2013 07:08
• Thanks for redoing the video so we could see the insides.
  
  My end thought on this is that the engineers wanted to do a god job but after the whole thing went to shit. I will look elsewhere because the user interface is crazy, and the build quality had many issues. Too bad that the whole thing got let down by the idiots building and programming it after the hardware design was done.
• #17 Reply
  Posted by PChi on 20 Mar, 2013 11:37
• Thanks for the Teardown. I think that Atten use two 2SD1047 in parallel for the 30 V 5A supplies because of the Safe Operating Area limitations. The ST Microelectronics data sheet Figure 2 shows 2 A at 50 V for DC. I guess that is with the junction temperature = 25 degrees C. I guess that with the transformer tap switching it should only ever be subjected to those conditions for a few ms so there is some margin for the Safe Operating Area getting smaller at higher junction temperatures.
  
• #18 Reply
  Posted by nitro2k01 on 20 Mar, 2013 12:46
• Hmm, are those thermostats normally open or normally closed? (Yes, it ought to be normally open with that configuration, but that's why I'm asking...)
  
  If you were trying to get a full load on CH2/3, shouldn't you have used the lowest setting on the CH3 rail to maximize the drop over the transistor? I see you're using the resistor for this though. So maybe even just put it into constant current mode byt shorting it out.
• #19 Reply
  Posted by PA0PBZ on 20 Mar, 2013 13:04
• Quote from: nitro2k01 on 20 Mar, 2013 12:46

  Hmm, are those thermostats normally open or normally closed? (Yes, it ought to be normally open with that configuration, but that's why I'm asking...)

  
  I was wondering the same, usually these things are NC but that would not make sense in this configuration.
• #20 Reply
  Posted by firewalker on 20 Mar, 2013 14:27
• Searching for "KSD302" shows N.C. and N.O. types.
  
  Alexander.
• #21 Reply
  Posted by nathancrum on 20 Mar, 2013 15:21
• I understand the camera rant in this video, but it was a bit more than a little over the top.  Also it seems more likely the memory card is to blame than the Canon, but I digress.  Thank you for redoing all the video regardless - it's much appreciated by us fans of the show.
• #22 Reply
  Posted by c4757p on 20 Mar, 2013 15:31
• Quote from: nathancrum on 20 Mar, 2013 15:21

  I understand the camera rant in this video, but it was a bit more than a little over the top.
  

  
  Eh, who cares? It was funny, and felt good for anyone who's had something similar happen.
• #23 Reply
  Posted by Winston on 20 Mar, 2013 16:07
• I was looking forward to you measuring the temperature of that electrolytic cap that's way too close to the heat sink.
  
  TI Power Tip 50: Avoid aluminum electrolytic capacitor pitfalls
  
  
  
  
• #24 Reply
  Posted by nathancrum on 20 Mar, 2013 17:02
• Oh yea - regarding the cap that was "way too close".  Electrically that may still be the case for adequate isolation (I don't know), but thermally speaking - it's at the opening to the (channeled) air flow for the heat sinks.  If anything that should be one of the best cooled capacitors in the case regardless of proximity to the heatsink.  The leading face of that heatsink should also be the lowest temperature point on it and emissivities of both shiny parts are not going to be great so thermal radiation isn't going to be terribly significant.
  
  The massive cap near the side of the heat sink on the other hand may have a nice gap, but it will experience basically zero air flow for cooling.  I would expect that cap to get much warmer than the one in the center of cooling air flow path.