Blow up my brand new power supply after 20 minutes of use. - Page 1
Forum section: electronics / beginners

author: Feynman81
author_rank: Newbie
timestamp: February 12, 2023, 08:57:12 am
content: Hello everybody,I bought myself one of those cheap 0-30V 0-5 A power supply from Amazon and after playing with it powering small motors and stuff I went on powering a small laser I had laying around and bang (well no bang actually) I blew up the fuse.I change the fuse, start the power again, and bang I blow the fuse again without doing anything else but pressing the main switch.I disassembled the power supply and found 3 electrolytic condensers that are shorted internally. I guess this might be the reason I keep blowing fuses but I don't understand why I got there in the first place.I was powering the laser no problem and all of the sudden the PS died. Can anybody help me? What did I do wrong in the first place and how to fix the thing for good, just replace the condensers?Thanks in advance.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 12, 2023, 09:08:41 am
content: You did nothing wrong, except to buy scam bullshit product. Request for refund and DO THAT QUICKLY. Con artist sellers usually try to play games with you trying to waste time beyond some time threshold after which you can't get the service provider (Ebay, Amazon etc) involved. Try to discuss it with the seller just once and after a few days of waiting, escalate it to Amazon.Usually you just get money back without seller requesting the thing back because return shipping would be too expensive for them to pay. Do not accept anything else but full refund.

author: wraper
author_rank: Unknown
timestamp: February 12, 2023, 09:10:43 am
content: Why did you take it apart instead of returning the garbage?QuoteBecause you bought garbage.

author: Feynman81
author_rank: Newbie
timestamp: February 12, 2023, 09:18:09 am
content: Well I guess I was trying to learn by fixing. The thing had many good reviews on Amazon and came recommended on many blogs.I`ll try to get the refund but where can I buy good affordable stuff? I bought electronic stuff on Amazon before and never got scammed.Should replacing the capacitors fix the problem? I paid the thing 45 Euros and live in Germany by the way.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 12, 2023, 09:28:52 am
content: Quote from: Feynman81 on February 12, 2023, 09:18:09 amReviews are always 100% positive on these sites because they push people to give positive ratings quickly after receiving the product, and in case of issues, they try their best to convince people to still give five-star ratings. Try it out; chances are high the seller offers you instant refundif you give them 5-star rating. Do not consent; instead escalate to Amazon, give 1-star rating and make the Amazon force the seller to do the refund. This is for greater good.Blogs are likely just automated bot spamming. These days the real "blogosphere" is basically dead.QuoteAre you really sure capacitors are shorted? Did you remove them from circuit for measurement, and if yes, how did you measure?Capacitors rarely short out. If you measured in-circuit, then it just means semiconductors (some discrete transistors or ICs) connected between the positive supply and GND just shorted, as they tend to do when poorly designed. Fixing the thing will be an interesting learning experience but won't necessarily be trivial as you need to understand what went wrong in the design. By some luck, it could be something simple, though.With that budget, I recommend you try to find a used high quality power supply, something like HP/Agilent 6632A or similar. They sometimes go below $100. Such real lab supplies don't blow up easily (you would have to do some serious abuse), provide accurate measurements of voltage and current, and allow control/measurements through a serial port.

author: wraper
author_rank: Unknown
timestamp: February 12, 2023, 09:29:06 am
content: It's very unlikely that capacitors are shorted, most likely it's something else on the rail. Basically the only real lab PSU with such power ratings and price is Gophert SMPShttps://www.aliexpress.com/item/4000092785116.htmland still it will be a bit more expensive. Linear PSUs at this price are scam. Usually they can output rated power, but not for long. And usually contain counterfeit components. Like fake power transistors and recycled capacitors from e-waste.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 12, 2023, 12:31:18 pm
content: Please post the link to the power supply on Amazon. I bought this cheap Chinese made power supply from Amazon for $129 at the time and it works well.https://www.amazon.com/Programmable-Single-Channel-Supply-MPS-3605LP-MATRIX/dp/B07Y86LBRY

author: nightfire
author_rank: Frequent Contributor
timestamp: February 12, 2023, 05:26:41 pm
content: In my experience, some not-too-crappy quality for a new SMPS began before Covid with about 70€, nowadays rather 80-90 €€€ for something in the ballpark of 0-30V and 3-5A.I myself got me a PEAKTECH 6225 A, which i am not unhappy with, but according to some blogs and people that fixed some kinks rather marks some kind of entry level sweet spot where there is a real company in germany that can be held liable for bigger problems.Yes, brands like Peaktech or Voltcraft do usually simple relabelling of products, but have to do at least some bit of quality controll, unless held liable due to german law...

author: Feynman81
author_rank: Newbie
timestamp: February 12, 2023, 08:39:51 pm
content: This is the PS I boughthttps://www.amazon.de/-/en/dp/B06Y5JLJ6Z?psc=1&ref=ppx_yo2ov_dt_b_product_detailsstarted the refund process with amazon, let's see how it goes.Can somebody suggest additional PS, even proven used models/brands to look for on ebay. I'm looking at some used agilent but they are in the realm of 200-300 bucks.

author: nightfire
author_rank: Frequent Contributor
timestamp: February 12, 2023, 09:18:49 pm
content: ALso some often referred brand in the lower budget realm is Korad, they are well known and sourceable from lots of resellers.There are also some companies that rebadge them, like Stamos soldering- got my electronic load from them- front panel changed, inside a pure Korad KEL102, but 30% cheaper...

author: mvs
author_rank: Frequent Contributor
timestamp: February 12, 2023, 09:24:30 pm
content: Quote from: Feynman81 on February 12, 2023, 08:39:51 pmIt looks like it was made by QJE. This SMPS power supplies don't like load dump much.If you can't send it back and you need to repair this unit, check output diode (TO-247 package mounted to heatsink/backplate).

author: JeremyC
author_rank: Regular Contributor
timestamp: February 12, 2023, 09:26:03 pm
content: Quote from: Feynman81 on February 12, 2023, 08:39:51 pmI know few people who own the SPD3303C from Siglent, I heard nothing but very good opinion. In the US list price is $299. In the EU you may want to check "Batter Fly" they have it for 249 euro, check the link below.https://www.batterfly.com/shop/en/testandmeasurement/alimentatori/alimentatori_dc/siglent-spd3303cLink to Siglenthttps://siglentna.com/power-supplies/spd3303c-series-programmable-dc-power-supply/Good luck.

author: dmills
author_rank: Super Contributor
timestamp: February 12, 2023, 09:34:33 pm
content: TTI/Thandar/HP/Agilent/Topward/Farnell (Might be more of a UK thing).Do not turn your nose up at an older unit with analog metering, they are generally cheap and get it done.There is a pile of rather nice Topward TPS-4000, dual 30V 3A, on ebay right now, for £90 each, which is not bad at all.I have an old Farnell (probably from the 90s) unit which is often my goto because it has an absolutely enormous meter on the front that can be set to show the current, far more convenient then the Agilent system supplies that have far too small LCDs.The problem with 'Not junk' is that even used, it cannot compete with new trash on price.

author: mwb1100
author_rank: Frequent Contributor
timestamp: February 13, 2023, 01:30:19 am
content: Quote from: Feynman81 on February 12, 2023, 08:39:51 pmI don't think I can say that I suggest it because I have never had one, but I've heard Korad power supplies discussed with positive impressions. Welectron has a low-end Korad KD3005D for 80 EUR, which is closer to your price range I think. I think welectron does free shipping within Germany:-https://www.welectron.com/Korad-KD3005D-Benchtop-Power-Supply-Screw-TerminalsHere's a teardown review on youtube:Also, email welectron and ask for the EEVBlog discount code (5%).

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 13, 2023, 05:17:29 pm
content: Quote from: JeremyC on February 12, 2023, 09:26:03 pmIt probably doesn'treallymatter - and simply personal preference - but I prefer supplies that allow programming the current without having to short the leads together... Of course, that seems to add a significant cost... I note the updated SPD3303X-E model that offers that feature (and a few others) is $100 more...

author: JeremyC
author_rank: Regular Contributor
timestamp: February 13, 2023, 05:38:59 pm
content: Quote from: TomKatt on February 13, 2023, 05:17:29 pmYou can program current limit in the SPD3303C without shorting the leads, you may preset few configurations and save them. It can be controlled using SCPI commands.Both, the X-E and C have the same 10mV/10mA resolution .Main differences between the X-E and C are:- The C model doesn’t have network interface and can be programmed using USB only.- The X-E model has nicer display with more details.Check this review:

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 13, 2023, 05:44:43 pm
content: Quote from: JeremyC on February 13, 2023, 05:38:59 pmYou learn something new every dayStrange that the unit is capable of programmatic current values (via SCPI), but doesn't provide the ability to do that through the front panel user interface...

author: mwb1100
author_rank: Frequent Contributor
timestamp: February 13, 2023, 05:58:23 pm
content: Quote from: TomKatt on February 13, 2023, 05:17:29 pmI believe the Korad KD3005D supports that. The user guide is here:-https://www.sra-shops.com/pub/media/docs/srasolder/instructions/kd3005d-user-manual.pdf(the PDF pages are out of order. It seems it's formatted to create a pamphlet by stapling down the middle)

author: JeremyC
author_rank: Regular Contributor
timestamp: February 13, 2023, 05:58:37 pm
content: Quote from: TomKatt on February 13, 2023, 05:44:43 pmVoltage and current can be programmed using the front panel. Watch carefully the Youtube overview (min 1:50 - 5:30).

author: TomKatt
author_rank: Frequent Contributor
timestamp: February 13, 2023, 06:37:15 pm
content: Quote from: JeremyC on February 13, 2023, 05:58:37 pmNot sure how I missed that - could have sworn I checked the pdf manual and saw it mentioning shorting the + and - terminals to set the current, but I see you are correct.That being the case, I've never really needed fancy displays or timer based programmability so the SPD3303C would certainly appear to a decent option. In fact, given the option I think I prefer good 'ol leds to fancy lcd screens.I've had good results with my Siglent SDS1104X-E scope and SPD1305X power supply - absolutely no issues with either.Didn't Dave do a teardown on a Korad unit? Likely a good value for the money, but I recall the front end was some kind of crazy resistor-ladder adc for measuring current...

author: Feynman81
author_rank: Newbie
timestamp: February 13, 2023, 08:00:02 pm
content: Thanks everybody for their input, I think I'm set on the Siglent SPD3303C somebody suggested, no more crap from Amazon from me.I think I'm gonna open a new post for suggestions on a oscilloscope to buy....

author: james_s
author_rank: Super Contributor
timestamp: February 13, 2023, 08:23:20 pm
content: There are already dozens of threads on entry level scope purchases, no need to create a new one, just go read the advice already given. Not much has changed in the low end scope market in the last decade or so. Siglent and Rigol are still the main players.

author: tooki
author_rank: Super Contributor
timestamp: February 14, 2023, 09:31:58 am
content: Quote from: mwb1100 on February 13, 2023, 01:30:19 amFor what it’s worth, I strongly recommend spending the few extra euros for the KA3005D (or KA3005P, the version with data port, which often costs the same as the version without). I own the KA3005D and have used the KD3005D, and while they’re both perfectly competent at delivering power, the added controls of the KA3005D are well worth it, in particular the output on/off and preset memory.

author: agehall
author_rank: Frequent Contributor
timestamp: February 14, 2023, 10:47:45 am
content: Quote from: Feynman81 on February 13, 2023, 08:00:02 pmThere are countless threads on that topic already - no need for anotherone. Just dig up any random such thread from the last 24 months and it will be just as relevant as if you post another thread about this.