Chinese eBay power supply lottery - Page 1
Forum section: electronics / general

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 30, 2014, 05:56:54 pm
content: Yeah, I'm a cheapskate sometimes and as my source forbudget (yet quality) 6V DC suppliesdried out, I tried to buy some oneBay. They were notextremelycheap (3.99€ incl. shipping), so I hoped they were about the same quality as the ones I used before.Only one of them delivered ~6V under slight load, the other two 5.8 and 5.2V (!). Since the three supplies behaved quite a bit differently despite of the identical product ID on the label, I decided to open them. Letting aside at least one case very close to a short circuit of the DC output voltage to its ground, I was surprised to find three completely different designs. The best one (performance wise) is based on a LNK603, one seems to be completely discrete and the third one (with the worst performance) uses a Melexis TH 2267.1 (where I found a datasheet from 2004) but is manually routed. The PCB of this last supply is labeled Friwo while the others are labeled Phihong.Up to now, I usually was lucky as all my China bargains were ok - even all of my el cheapo FTDI boards used genuine ICs. But these supplies really look as if they refurbished everything even close to a 6V supply and put them in the same case to pretend a common origin. Since the PCBs are from at least two different countries and don't seem to come from different years, I find it hard to think of any other explanation than refurbishing. This would probably also explain the weird voltage levels. The Friwo one with 5.2V output is probably a 5V supply put in the case of a 6V supply.Since they're not completely readable on the pictures, the PCB identifiers are:Phihong PSM05E-050N-HPhihong PSM05E-050NC-HFriwo 15.2382.505-4

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 06:23:19 pm
content: They are all have Nokia charger PCB inside, AC-4E I think. They are different because Nokia have multiple charger suppliers with different design. The reason why voltage drops is because they are intentionally made so. They drop voltage under load by design. So my guess is, thay had a big pile of used nokia chargers and new enclosures. BTW actually you are lucky because they are safe unlike crap china PSUs.

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 06:37:53 pm
content: Might be AC-8E too. Disassembled my AC-8E from friwo, it is very similar to the last one but not the same. One year newer date code on the PCB.

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 06:44:11 pm
content: Cracked open another AC-8E, yay

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 30, 2014, 06:53:41 pm
content: Yeah wellI could have bought these for under 2€ or less if I wanted Nokia chargers

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 06:55:36 pm
content: No, you would buy fakes which can supply only about 500 mA instead of 890mA specified and are dangerous as hell.

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 07:01:32 pm
content: Actually I have one, not of the worst kind. So you are lucky indeed.

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 07:18:12 pm
content: Btw, dropping voltage under load is used for detecting fast/slow charger. Slow is about 400-500 mA depending on model. If charger is not dropping voltage under load, nokia phone will refuse to charge and show "Not charging" on LCD. That's why fake chargers stating 890mA can work. Phone thinks that it is slow charger.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: October 30, 2014, 08:28:21 pm
content: Quote from: wraper on October 30, 2014, 06:55:36 pmNot necessarily.Usually Pollin sells overstock stuff, but not dangerous China crap.

author: wraper
author_rank: Unknown
timestamp: October 30, 2014, 09:34:17 pm
content: Quote from: 0xdeadbeef on October 30, 2014, 08:28:21 pmEven if it is kinda OK, it definitely isn't even close in quality to genuine nokia.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: November 02, 2014, 11:36:16 am
content: Well, the price of 3.99€ I paid quite exactly equals $5 and the supplies were said to be shipped from Hong Kong.Anyway, I guess a power supply is a product that is especially easy to fake/clone, so even if I had known a specific product ID for a 6V/1A supply, chances are I'd ended up with a fake one as well.

author: metalphreak
author_rank: Frequent Contributor
timestamp: November 02, 2014, 01:47:43 pm
content: You can't base quality on price either. There are plenty of sellers who will list a $2 item for $10 in the hopes that someone will think "more expensive it must be better" and then they make 4x the profit...The biggest giveaway on fakes are the serial numbers. They will all have the exact same serial. Costs too much to do individual laser engraving

author: bktemp
author_rank: Super Contributor
timestamp: November 02, 2014, 01:56:11 pm
content: Quote from: metalphreak on November 02, 2014, 01:47:43 pmThat is the main problem with all the cheap chinese stuff. There is no way to know if it is worth the money by ony looking at the description. The only way is to buy a few samples, take them apart and look at the build quality. If it is good, you can buy more and hope they have not changed the design in the meantime.

author: dannyf
author_rank: Super Contributor
timestamp: November 02, 2014, 02:08:20 pm
content: QuoteOr you can go to your trusty neighborhood store (or a distributor) and buy a quality adapter and save a few dollars in the process.Why pay more to get less?

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: November 02, 2014, 03:46:52 pm
content: Quote from: dannyf on November 02, 2014, 02:08:20 pmIf it only was that easy. As I said in the 1st post, my original source dried out so I searched quite a long time for alternatives. Unfortunately, all I found was around three times the price I originally paid - or even more. In the end I ordered some supplies for 9€ (each) now. Saving money feels different.

author: dannyf
author_rank: Super Contributor
timestamp: November 02, 2014, 04:16:49 pm
content: Beats out paying 4euros for a supply that you cannot use.I am too poor to buy cheap stuff.

author: 0xdeadbeef
author_rank: Super Contributor
timestamp: November 02, 2014, 05:51:04 pm
content: Well, I decided to keep the refurbished supplies and use them only for my private stuff, but I won't risk to give them out of my hands as even if they had CE/VDE/whatever certifications in their original state, they lost them as they were refurbished. So they are not a total loss. Besides, the dealer offered a refund, so depending on how we'll settle, this might be an ok deal after all.Anyway, I can't agree with the "I am too poor to buy cheap stuff" statement in its absoluteness. As I said I bought quality power supplies for less before and I bought a lot of (carefully selected) ultra-cheap stuff from China which was as good as expected or even better. Obviously, below a certain price point, you can expect to get crap, but for what I paid one could expect ok quality.Buying expensive and/or at a local dealer is no guarantee to get good quality either. So having one bad experience in years of good deals is no argument to change my strategy.