Laptop charger with Hiccup as damage .. Help !! - Page 1
Forum section: electronics / projects

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 13, 2011, 12:42:55 pm
content: I got before a year ago one spare charger for my ACER laptop.I had test it in the first day (quick test) and never again, until today that I decided to test it again.The PSU haves an issue , when the laptop starts to need charging amperes the 19V output jumps down to 15V and up to 19 again.I open it up ( butchers way) and replaced the two electrolytic 1000mF 25V with 2X 2500mF 25V.And even after this attempt, I still have the issue..There is also one capacitor in the primary , 120mF 400V, but this looks fine, and measures too.Any ideas ?There is no need to say that this PSU came from China (ebay) , with all the stickers that is an ACER LITEON Genuine PSU.At 19V 3.42A ..With out load gives a stable voltage level.The output transistor are a single STPS20H100CT.The original PSU works fine, but I need to bring this one back to life, too.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 14, 2011, 12:50:25 am
content: I did try all my magic spells on it, re-soldering parts ,checked all the caps.Nothing helps.Thats a nice death for one unused PSU .And the funny part is that there is no heat or sparks, or a sign from the God of what is wrong with it.If some one has an schematic about a similar PSU it would be nice to post it.

author: IanB
author_rank: Super Contributor
timestamp: October 14, 2011, 02:10:48 am
content: Why do you think there is anything wrong with the power supply? Does the computer give an error message? Does the power supply switch off or stop working?In fact, how can you even tell what the output voltage is doing without breaking into the DC power cord?

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 14, 2011, 03:09:18 pm
content: I did break in the DC plug first , I was hopping that was an bad made plug.As soon I replaced the DC male plug and made my measurements, I found what really happens.What happens from the side of the laptop:As soon it detects that the voltage drops to 15V from the 19V,does not start the charging mode.With a healthy PSU it works beautifully.I am very well informed about issues that can possibly haves to do with the condition of the on board female power plug,and I am even prepared, I got a genuine spare one in the salty price of 7EUR before a year time.

author: david77
author_rank: Frequent Contributor
timestamp: October 14, 2011, 03:26:34 pm
content: What type of SMPS IC are they using there? Maybe a look at the datasheet might help you.I don't like that they left out all the mains protection and filtering. Every penny counts I guess.

author: Unknown
author_rank: Unknown
timestamp: October 14, 2011, 03:43:31 pm
content: There is a fuse in there, even though a wire would have saved another $0.01! Cheap crap: you get what you pay for I guess.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 14, 2011, 03:44:25 pm
content: They use as I have wrote the STPS20H100CT.I had just contact LITE-ON by email, lets see what they will have to say about it.I had request technical help, or replacement plan.The item was bought from the ebay channel, and so I can not track down and ask help from the anonymous seller.From the other hand, if this item is a fake product marked as LITE-ON,I would be glad to help LITE-ON so to track down the maker of those, who actually causes damage to them.

author: jahonen
author_rank: Super Contributor
timestamp: October 14, 2011, 03:50:42 pm
content: I'd try replacing the 120µ 400V capacitor (anyway), and the small electrolytic one near the IC (not output capacitor but it probably filters the controller ic supply voltage).Regards,Janne

author: david77
author_rank: Frequent Contributor
timestamp: October 14, 2011, 03:51:49 pm
content: No, the SMPS controller is not the STPS20H100CT. That one is a double schottky rectifier. I was talking about the DIP8 part on the mains side of the board.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 14, 2011, 04:03:13 pm
content: Here is a picture from my primary and healthy LITE-ON charger.About the Primary circuitry IC I will have a look about it.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: October 14, 2011, 04:10:54 pm
content: Funny you should mention this. My Acer power supply just died the other day. It's the 19V, 7.11A model and powers a mini desktop (Aspire?). It just suddenly went completely dead. It's potted so I couldn't get it open. I dug around in the trash at work and found an old Dell PS with a bad cord. I transplanted my cord and it seems to work fine. For a while I ran the computer from my bench supply with a meter and noted that it draws up to 4A on startup, then averages 2-3A after that. I use it to control my GPIB test equipment.

author: oliver602
author_rank: Regular Contributor
timestamp: October 14, 2011, 10:47:59 pm
content: That input capacitor's rubber bottom looks a bit bloated to me. Normally they are perfectly flat?

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 15, 2011, 05:11:19 pm
content: I did replace and the 120mF 400V capacitor with a better quality one,I got a tiny improvement, but not stable output under load.Thanks for the PDF , I will study it and see if can get any fresh ideas from it.

author: jahonen
author_rank: Super Contributor
timestamp: October 15, 2011, 05:26:38 pm
content: Quote from: Kiriakos-GR on October 15, 2011, 05:11:19 pmDid you try replacing the small capacitor near the controller IC?Regards,Janne

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 15, 2011, 05:38:06 pm
content: I was ready to do that but I got as freeby one damaged Toshiba similar PSU and the small capacitor in it was just 10mF,in my unit it is 47mF , and I though to skip the replacement of it.But yes at this point if I do that, the electrolytic capacitors get out of the equation, as possible source of the evil.

author: BravoV
author_rank: Super Contributor
timestamp: October 15, 2011, 06:22:36 pm
content: Let me give you a suggestion, forget about that crappy charger adapter, its not worth all your trouble, time & energy to fix it.Also the most important part is you don't want this to toast your laptop, worst your important data or the hard disk got zapped, who knows, things like the primary circuit got connected to secondary side even its using opto coupler is possible, heck, I believe anything imaginable could happened with this type of cheap fake charger.Fyi, these type are the cheapest and the lowest grade known made by unknown home industry back in China and usually they just re-labeled as the fake one and sell at a very cheap price. I live in this Asia region, not sure at Greece, this is a well known "public" secret here.Usually the easiest part to identify is you can see the missing X Y cap & the choke filter, also most of the time, the switching transistor is not using the rated one, and if you buy another same & exact charger from the same same batch, sometimes, if you're "lucky", they might using totally different switching transistor rating type for the same exact model.he..he..Its no secret that during manufacturing, they just soldered what ever transistor that was available as long they have the same physical body size and they won't burn up when turned on, thats all. And almost majority of them are using the transformer that is not rated to the job, the transformer core will get saturated easily even at 50% load. Too bad you don't have an oscilloscope, you can easily spot those points I mentioned.Here, let me show a decent laptop charger adapter, and see for your self and compared with yours, I believe with your experience you should know better. This poor charger experienced a lethal drop from 4 meters height, and the top cover was heavily damaged and shattered into pieces, amazingly its still working fine, but since its exposed and no longer properly shieled, I'm currently using the replacement new one.Bottom cover with the label and the main unit, look how it is shielded & covered with copper for better heat dissipation and lower emi footprint, its soldered to the ground plane, while the top cover was discarded long time ago.At the top, both top & bottom copper covers, and at lower right are the inner stiff, high thermal resistance and transparent plastic shield wrapping to isolated those copper shield from touching the components or board.Top view, I believe I don't need to explain on how this one compared to yours, simply this picture tells thousand words.The easiest part to spot is the primary cap is using Nippon Chemicon that is well known.Bottom side.

author: BravoV
author_rank: Super Contributor
timestamp: October 15, 2011, 08:06:44 pm
content: This is your lucky day, I'm in the mood of taking pictures, here more detail shots.Side view, see how thick the facing copper heatsink is ?Another side, these are aluminium, still using thick one, and at the copper you can see the two transistors clamped nicely with the pink thermal pad at the copper sink.Here, better view.Another angle.More ..Now, the secondary section, look at the top with brown soldering mark and residue, two schotky diodes are soldered at the top heatsink and this is the best method for disspating the heat than using pad or paste, and the most obvious is those secondary cap from Rubycon, I bet you know this brand right ?And if anyone of you that have sharp eyes, watch that blue capacitor at the front, you will notice one of it's leg has a nice ferrite ring for suppressing the high freq spike/noise, nice detail huh ?Final one, the nice copper shielding, with the current skyrocketing copper commodity price, not sure, I guess this two pieces of metal and their manufacturing cost, they probably cost half of your crappy charger there.Now, you've seen the difference, and both charger are rated similar power output, the simple question is are you expecting your charger will behave nicely, compared to this one here ?Save your sanity, buy a good original charger and dump that piece of junk.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 15, 2011, 09:46:57 pm
content: I did and the last cap replacement, no Go...I just use my U1272A DMM and did a data-log, by monitoring my ACER charging current with the use of my professional bench supply,I will add the chart soon.BravoVPlease man never by pass the forum limitation again .... about showing the images at full size , you did killed my bandwidth man,and its very few right now, on a troublesome wifi connection !!Its truly bad idea doing that, and you doing it allot .

author: BravoV
author_rank: Super Contributor
timestamp: October 16, 2011, 06:45:58 am
content: Quote from: Kiriakos-GR on October 15, 2011, 09:46:57 pmSlow speed voltage logging wont solve your problem, its fine though for checking the regulation "assuming" voltage's ripple is within specification, the problem with those garbage charger is their ripple might way too high and possibly with the over saturated transformer or overloaded switching transistor since they're under rated, the voltage reading might get really crazy for that slow voltage logger to capture.The only tool is to use oscilloscope to capture this kind of problem if you keep insisting in fixing and using that crap. You should not allow such garbage to get near your laptop especially you've seen the difference between the good and bad examples.Quote from: Kiriakos-GR on October 15, 2011, 09:46:57 pmWhat forum limitation or rule ? Show me, and please not the rule made by you.All my images size are 1024 width which is acceptable for today modern monitor or laptop, and those are scaled down too. Looks like you rarely hang around at multiple forums at the internet do you ? These are norm.Also check your own images size, yours are bigger than mine silly man, its just different orientation, and your internet connection trouble is your own problem, fix it yourself and nobody care. So far no one ever complained about my posted images size at all my postings except you alone in this forum.

author: ciccio
author_rank: Frequent Contributor
timestamp: October 17, 2011, 08:32:11 am
content: Quote from: BravoV on October 16, 2011, 06:45:58 amPeace!I do not have a slow connection, and I download the images fast. The images are a bit too large for my home display (I have to right scroll the window) but I can see them well on the work display (true HD resolution). I know the problem is my old home PC, using Win2000 and Opera.Maybe a newer browser will resize the images.Regards

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 17, 2011, 12:46:05 pm
content: ACER Travel Mate 2410Discharged:Charging currenta) Beginning 1250mAb) Max 1300mAc) End of charge at 370mA, and returns to charged state with 37mA minimum consumption.Charging and power on:a) Idle 2200mAb) Multitasking 2500-2900mA ( Wi-Fi on & LCD brightness 25% )The numbers show that I do need a truly honest laptop PSU for my own laptop.In this specific case, I have to admit that I got fooled by some scam bags,Who had rebadged underpowered PSU for very old laptops and selling them as 3.42AEven the power cable internally was not in the proper diameter for such currents.I did replace it too with a better one, but the gain from it, it was not enough for improving the PSU performance to the point of be acceptable.The ebay seller who sold this to me called as Gadgets_ProI got this PSU as spare and never use it since 10/08/08.I had it in storage all this time.http://myworld.ebay.com/ebaymotors/gadgets_pro&ssPageName=STRK:MEFSX:SELLERIDAfter my first power consumption measurement (thanks to the U1272A data logger),I would say that even the 3.42A version, it would work near to it limits if it charge the battery and feed the laptop too.My next choice would probably be something at the 4A+ mark.About mister Bravo, I will just add him in my ignore list, until 2012.This will stop his own norm from killing my Wifi zero signal connection.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 17, 2011, 05:43:18 pm
content: The IC are a KA3842A .And the large transistor next to it a K2333.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: December 07, 2011, 03:58:36 pm
content: I have to add one latest picture of an true Liteon charger that I got as gift due the reason that the original DC cable was damaged by the user,at the point that comes out of the PSU, and so there was no easy solution to be replaced.And so I got it, so to try to replace the cable and keep it for me.And I did managed to crack it open with out damage, and by opening it up I found lots of glue in it.The idea is that LITEON does not have in mind repairs, and they did fill it up with lots of glue.Luckily the PCB at the side of the cable was clean, and I did manage to replace the cable.