Voltcraft LSP-1403 - teardown - Page 1
Forum section: electronics / general

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: September 24, 2011, 03:20:49 pm
content: Here is a little power supply i acquired. Quite unique because of its slim factor. All specs are achieved and i like it.However the unit overheats pretty quickly so time to cut a hole in the case (only spot available was exactly a sweet spot), trace a 5 V power supply lines and install a quiet fan.Enjoy

author: saturation
author_rank: Super Contributor
timestamp: September 24, 2011, 04:20:00 pm
content: A fan can't hurt. Based on the photos it looks well made, and certainly unusually deep but thin. Would be curious to see what its ripple, noise and load regulation are.

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: September 24, 2011, 04:29:38 pm
content: Quote from: saturation on September 24, 2011, 04:20:00 pmI will check them once i finish the lab. I installed the fan in the end at couch in living room

author: IanB
author_rank: Super Contributor
timestamp: September 24, 2011, 06:42:58 pm
content: Are the voltage and current regulation knobs continuous or discrete? I looked at a supply just like that with a different brand name, and the voltage regulation worked in steps making it difficult to get exactly 5.000 V for example. On the other hand, stepping knobs are not going to wear out and become noisy over time like an analog pot might.

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: September 24, 2011, 07:42:32 pm
content: Quote from: IanB on September 24, 2011, 06:42:58 pmKnobs are not pots but rotary encoders without "end" and they have very fine steps. Its pretty easy to dial anything

author: IanB
author_rank: Super Contributor
timestamp: September 24, 2011, 07:56:58 pm
content: Quote from: hacklordsniper on September 24, 2011, 07:42:32 pmIf you want to dial up 4.200 V for example, what are the steps on, above and below that value?

author: IanB
author_rank: Super Contributor
timestamp: September 25, 2011, 08:08:23 pm
content: I've been looking for a power supply for a while, and after reviewing options I picked up theExtech 382260, which seems to be like the Voltcraft one. I've played with it a bit, and I like it.The answer to my question above is that the voltage is adjustable in steps of approximately 0.1 V, and the current in steps of about 0.01 A. It means I can't dial up precisely 5.000 V, but then none of the other lower priced power supplies I looked at could do that either. And I really didn't like the operation of the coarse and fine adjustment knobs on some analog supplies I looked at for comparison. The compact size and light weight of this supply is really pleasing considering its range of outputs.My follow up question is what did you do to make it overheat? I tried running a 12 V 4 A load for a while and it remained completely cold. I also experimented with other loads in constant voltage and constant current modes and the case didn't even get slightly warm.

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: September 26, 2011, 08:13:21 am
content: I connected a H7 55 W lightbulb as burn in test and after hour the casing was hot and internal components were surely much more hot.

author: saturation
author_rank: Super Contributor
timestamp: September 29, 2011, 01:49:00 pm
content: One thing I do with these Chinese made products is test the temperature of the heat sink at max load. Most junctions are rated to 100+C, so if the final temp is above that, it will certainly shorten the parts life and the product life and worth cooling down. The thermcouple probe on your DMM is perfect for such tests.Quote from: hacklordsniper on September 26, 2011, 08:13:21 am

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: September 29, 2011, 05:47:11 pm
content: Quote from: saturation on September 29, 2011, 01:49:00 pmI always use a temperature probe but just forgot the readings of this instrument

author: IanB
author_rank: Super Contributor
timestamp: September 29, 2011, 06:09:26 pm
content: I'm not inclined to take mine apart, but there are air vents along the top of the case and from my testing so far I have seen no sign of warm air currents, warm case, hot smells or any other signs of heat. On my test 50 W load everything seems to remain stone cold for long enough to run a test and take measurements. So for my purposes I don't seem to have any overheating problems.

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: September 29, 2011, 07:21:37 pm
content: Quote from: IanB on September 29, 2011, 06:09:26 pmMaybe your unit has better heatsinks or it features better quality build. I dont know

author: 74HC04
author_rank: Contributor
timestamp: October 02, 2011, 10:29:58 am
content: It's likely that the ODM of this model is Manson of Hong Konghttp://www.manson.com.hk/en/dcpowersupplies_detail.php?m=2&id=32.I have a Maplin Branded NRP-2050 which I'm fairly happy with. I just wish it had multi-turn pots.http://www.manson.com.hk/en/dcpowersupplies_detail.php?m=2&id=16

author: MBY
author_rank: Regular Contributor
timestamp: October 04, 2011, 02:57:18 pm
content: Hi! My first post!I just received a LSP-1403 from Conrad. The unit works well within the limits. The encoder lets me set voltage in steps of 10 mV and current in steps of 10 mA, but the repetitiveness is somewhat poor. It is not exactly 10 mV/mA, but something similar. If I set 2.35 V and increase the knob one step, the setting is 2.40 V. On step down, and the setting is 2.30 V.Anyway, I have a problem. Under two volts, the voltage display jumps between actual setting and actual setting + 1 V in 500 ms intervals or so. This is regardless of load and regardless of output on or off. If I check with a DMM, there is no problem with the output, just the voltage display. The voltage goes from about 100 mV and up to 2 volts and beyond, no problem at all. But the display simply does not work as expected at below 2 V (on all ranges).I asked the Conrad support, but they did not answer as clearly as I expected. They want me to return the PSU. I wonder if I should try to fix is my self, but I have no ideas of whats wrong.Anyone else who got problems?

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: October 04, 2011, 05:13:22 pm
content: I just tried mine and there is no such problem. It is best to replace your unit

author: MBY
author_rank: Regular Contributor
timestamp: October 05, 2011, 11:33:11 am
content: Thank you! I was worried it was a bug and such affected all units (the problem is so peculiar that I found it implausible to be a HW issue). Now I have motivation to get the unit replaced.Will tell you how it went if/when I receive a replacement unit!

author: hacklordsniper
author_rank: Frequent Contributor
timestamp: October 05, 2011, 01:12:26 pm
content: Quote from: MBY on October 05, 2011, 11:33:11 amWhat SW version do you have?

author: MBY
author_rank: Regular Contributor
timestamp: October 05, 2011, 02:10:38 pm
content: No idea! Currently the unit is on its way back to Conrad. I did not realize you could get the version. The manual does not say, but I know that pressing REVIEW and range 16 V at the same time brings up some cryptic message. If you do it twice, the voltage display shows "CALb" and the current display shows 0000. Some calibration mode obviously. But maybe the cryptic message before "CALb" is a version number. I do remember that the current display is "---E", but I don't recall the voltage display.There may be a sticker on the chassi telling the SW version, or maybe a sticker on a chip? I don't recall seeing anything about a SW version, but when I get hold of a working unit I will take it apart!...More reviewish: The encoder buttons are too close I think. It's hard do adjust current without unintentionally adjust the voltage encoder. I have another PSU from Manson, the probable ODM. It's not the same instrument, but a NSP-3630. The encoder buttons are similar and the "not so exact" setting of V and Amps is pretty much the same. But the spacing between the buttons is greater on NSP-3630 than LSP-1403/SSP-7080.The NSP-3630 has poor current limit, it's slow. Almost so you suspect it's software control-loop. I haven't have the time yet to test LSP-1403, but I will report when I got a new unit. I hope this one is faster. I actually removed a output cap on my NSP-3630, trading ripple for current limit speed. It didn't help much. I also have a bigger PSU from Conrad (I'm unsure of the ODM) called PSU2010 or something similar (20V, 10A). It's also switched and has a serial port for PC control. It's really fast on the current limit.Anyway, sorry for "stealing" your thread and speak about other irrelevant PSUs.Nice mod btw! I will consider something similar if my new unit runs too hot!

author: MBY
author_rank: Regular Contributor
timestamp: December 09, 2011, 11:56:29 pm
content: Oh, I forgot about this thread! Conrad returned me a new LSP-1403 a couple of weeks ago and it performs well. No funny business below 2 VDC. I haven't done a teardown, but I don't think I need to. I tried to output about 60W (on 16V range) for a couple of hours and while it of cause heats up, it is not that bad. So I won't add a fan this time. The meters seems to perform well, the voltage is a few counts off (according to a Fluke 45 and a Rigol DM3061) but the current is spot on!

author: IanB
author_rank: Super Contributor
timestamp: December 10, 2011, 12:44:43 am
content: I continue to like my Extech 382260 version. It does just what I want of it, and it hasn't got the slightest bit warm with the loads I've put on it (a few amps at low voltages for an hour or two charging batteries, for example). With my brand new Rigol DS1102E I can even attempt to measure the ripple on the output.I particularly like the way the output is always off when you first power it up, and the review mode where you can adjust the voltage and current limits with the load disconnected. The four wire remove voltage sensing also comes in handy from time to time, and the lack of fan noise (no fan) is excellent.

author: chrisx
author_rank: Newbie
timestamp: October 11, 2012, 11:04:03 pm
content: Hi GuysFirst, Thanks for this very informative post.I am also considering one of those Manson-designed switch-mode PSU... And I have a big critical question:Are the + & - output isolated from the mains ?(In other words, can we for example connect 2 PSU in series to get double the voltage)Thanks to anyone who has an opinion on this

author: Wytnucls
author_rank: Super Contributor
timestamp: October 12, 2012, 04:49:56 am
content: No, 2 or more units can be hooked up in parallel to increase output current, but not voltage. Master and slave configuration, with one unit controlling all the others. 36V not enough for you?

author: chrisx
author_rank: Newbie
timestamp: October 12, 2012, 12:43:32 pm
content: Thanks WytnuclsI would like to go up to 50V or more for some projects.I know about the parallel operation as described in the manual. I still not sure whether this can be done or not. Presumably, any lab supply should have its - & + outputs isolated from mains... But few manual actually state it

author: mariush
author_rank: Super Contributor
timestamp: October 12, 2012, 03:54:23 pm
content: See the Tenma I bought:https://www.eevblog.com/forum/product-reviews-photos-and-discussion/tenma-72-8695-2-x-32v-3a-5v-2a-mini-review-teardown/You can couple its two outputs to have up to 64v 3AIt's linear though, heavy.

author: Danielw
author_rank: Contributor
timestamp: December 15, 2020, 08:52:15 am
content: Found schematic on this unit:https://www.produktinfo.conrad.com/511632My unit stopped working, I figured out that U9 died and got shorted internally, magic smoke etc.Is anyone brave enough here to check if U9 and U16 are read-protected? Easy swap but without firmware I would have to reverse engineer the firmware, U16 is ok but I dont see any communication on A1+B1 (CON8)