Buy broken Takasago power supply or not? - Page 1
Forum section: electronics / beginners

author: Asuka
author_rank: Regular Contributor
timestamp: November 29, 2017, 08:26:43 am
content: Hi, electronics beginner here. I have been considering buying a power supply and by coincidence I found a second hand DC fixed voltage power supply at the local secondhand shop. The power supply at the moment does not work (does not come on even if power supplied). The cost is 5000 yen (about $50 US). The model name is Takasago KX-210L. I've seen lots of videos on youtube of people fixing power supplies by exchanging the capacitors inside or some such simple fixup which I think I could do. Would it be a good idea to gamble on buying this power supply with the hope of fixing it by replacing some capacitors or a fuse, or is that a stupid idea? I was able to take the power supply to the bench in the secondhand shop and confirm that it does absolutely nothing when power is supplied.The staff in this shop often have absolutely no idea about anything they are selling and they don't repair goods before putting them on sale.

author: ataradov
author_rank: Super Contributor
timestamp: November 29, 2017, 09:50:47 am
content: This looks like a good power supply. I would definitely pick one up for $50 and a chance to fix it.EDIT: It appears the price of a new one is over 100k yen.

author: Asuka
author_rank: Regular Contributor
timestamp: November 29, 2017, 11:39:21 am
content: Thanks for replying, I appreciate it.Quote from: wilfred on November 29, 2017, 10:33:11 amThey know it doesn't work at all.Quote from: wilfredThe shop doesn't accept offers. There is a sign telling people not to make offers.Quote from: wilfredI've seen lots of videos on youtube which make it look like usually one just opens the case and changes the broken electrolytic capacitors and "bingo!" but I'm not sure whether they are realistic or not. I am able to do basic soldering stuff like replacing capacitors, or I could replace fuses but I don't have a lot of diagnostic tools beyond a multimeter, so I wonder if it would be better to buy a new cheap power supply.

author: kalel
author_rank: Frequent Contributor
timestamp: November 29, 2017, 02:38:40 pm
content: It could be safer to buy a cheap new one (if you can for a similar price), but it's hard to know which cheap power supply is good or bad (unless you can find reviews). When buying a new one, you probably get warranty and can return if there are any issues within a reasonable time.On the other hand, if you can repair that one, youmighthave a better quality supply, I don't really know anything about the model. I'm also not experienced at repairing them.I would say try to repair it only if:1) You want to tackle a new project and experiment. In this case, take all safety cautions when working and when testing.2) A new "cheap" but working supply is much more expensive (not 20-50%)3) You don't 100% rely on being able to fix it. Maybe it's not easily fixable and you should be ready to take the risk.If you do decide to get it, feel free to take some high resolution (if possible) photos and ask for help. There are many experienced folks here who actually like to share the knowledge.If you decide to be safe and not get it because you can find a decent deal for a new one (or a working used one in local ads) that's a good choice too.In the end, whatever you choose, good luck.

author: CJay
author_rank: Super Contributor
timestamp: November 29, 2017, 02:41:15 pm
content: Quote from: Asuka on November 29, 2017, 11:39:21 amSwitch mode power supplies aren't always an easy fix for anyone, they can fail quite spectacularly and can be very dangerous to work on if you're not sure what you're doing.It's possible it could just be something as simple as a resistor that's gone high in value or open circuit, capacitors also regularly fail, low value ones in the primary of the power supply can cause no start problems.If you know how to work on mains electrical items *SAFELY* and can afford to take a chance that it might be a complete loss then I would buy it but none of us want to see anyone hurt so if you're not sure you can do it safely, buy a working power supply instead

author: rstofer
author_rank: Super Contributor
timestamp: November 29, 2017, 02:50:49 pm
content: Can you get a schematic? Do you have a lot of experience with electronics? Do you know about the dangers of switching mode power supplies (assuming this one is an SMPS)? If the answer the ALL 3 is yes, then maybe it's worth something.Personally, I wouldn't touch it with a stick. I want to USE power supplies, not have them spread all over my bench.Those YouTube videos are of the successes, there won't be any videos of the failures. In most cases, it was just luck.

author: 3db
author_rank: Frequent Contributor
timestamp: November 29, 2017, 02:57:08 pm
content: I would buy it anyway.You could most likely sell it in its current condition for more than you'll pay for it.

author: cybermaus
author_rank: Frequent Contributor
timestamp: November 29, 2017, 03:24:54 pm
content: Quote from: 3db on November 29, 2017, 02:57:08 pmA pre-owned power supply with digital controls and unknown failure condition?An inexperienced person (he mentions only having a iron and dmm)In a country obviously foreign to OP (he mentions he needs to read the English sign) so he does not know the local market to resell it afterward?Maybe if $50 is pocket change for you , yes.But my pocket money level is lower than that.But to me it sounds as if he has $50 to spare, he should start with something that is known to work, and some DIY kits.Maybe one of those simple power supplies Dave tested the other day.

author: cdev
author_rank: Super Contributor
timestamp: November 29, 2017, 05:50:32 pm
content: If it doesn't work I would offer them no more than $10 max to start. And I would never pay more than $15-20 unless you have found its service manual and identified what expensive parts might have gone bad and figured out a plan to repair them. You should consider their cost as part of the price. Its likely they already have done this and figured out its not worth their time for them to repair.Nomatter how much it might be worth working, if something is sold as broken, major parts may well be nonfunctional. You simply don't know. If so, unless you have the skill and possibly additional parts to rebuild a new supply in the box (which is time so it equals money) its as likely as not to just become an expensive paperweight.I bought a broken (classic) Sorenson XT (similar to Xantrex) triple linear power supply a few months ago but only one-of three- well actually, six- displays three numeric, three linear, were broken, the power supply still worked.. it was a 3 in 1 supply that was made in the 1980s but that model is still being sold. (which tells you it is a classic design that is always going to be worth decent money to resell. ) But I could see two out of the three parts were working perfectly. So I figured that would make it easier to fix the third part. It turned out to simply need a digital voltmeter chip which was socketed and cost $5. So that was an easy repair.However, newer power supplies are less likely to use standard components. They might use ASICs which are "unobtainium". Consider that possibility. You should check if there is a service manual. Don't buy it unless you have a service manual. Certainly don't without test equipment (like an oscilloscope and 10x probes that let you measure high voltage). Switching power supplies contain high voltage.

author: Seekonk
author_rank: Super Contributor
timestamp: November 29, 2017, 08:52:06 pm
content: I've bought a few nice broken power supplies and never replaced a capacitor in one of them. Most had quite tricky problems. I've bought REALLY nice Xantrex power supplies for less than $50. You have to learn somewhere. Just put a 100W lamp in series with the AC power to limit current. Any good supply will operate with this lamp in series with a very dull glow. Only an idiot puts a new fuse in and sees what happens.

author: glarsson
author_rank: Frequent Contributor
timestamp: November 29, 2017, 09:05:55 pm
content: Quote from: Seekonk on November 29, 2017, 08:52:06 pmUnfortunately, this does not work for switching power supplies with a PFC circuit.

author: Asuka
author_rank: Regular Contributor
timestamp: November 29, 2017, 11:04:35 pm
content: Quote from: cdev on November 29, 2017, 05:50:32 pmThe person who sold it to the second-hand shop might have done that, but the shop definitely did not attempt any repairs.

author: Terry01
author_rank: Frequent Contributor
timestamp: November 29, 2017, 11:16:52 pm
content: Have you checked there's even anything inside the box? If its linear at least you would feel there was something in it. With a smps it may be an empty box!Good luck however you go.

author: Asuka
author_rank: Regular Contributor
timestamp: November 29, 2017, 11:52:42 pm
content: Quote from: Terry01 on November 29, 2017, 11:16:52 pmA good point to check for, but it actually weighs rather a lot. The manufacturer's spec sheet gives a weight of 3.6 kilograms. I didn't weigh it to check for missing parts, but I lugged it over to the test bench yesterday and can confirm it is a quite seriously heavy object. There is actually a handle on top of it, which looks like overkill until you try to lift it up.Quote from: Terry01 on November 29, 2017, 11:16:52 pmThanks. I'm going to buy it, try to repair it myself, then send it back to the manufacturer for repairs if I can't do it myself.

author: cdev
author_rank: Super Contributor
timestamp: November 29, 2017, 11:56:44 pm
content: Sending it back to manufacturer may cost a LOT. It certainly would not be a cheap PS at that point. If you could not pay then they would simply keep it. This is why you should offer them a lower price. There are a lot of reasons it could end up costing you a lot to get a working supply.Have you looked at the sites listed in the wiki here for aservice manual? Is it a quality brand? It looks like itmightbe a quality supply, but you never know, if its an unknown brand.You should edit the thread name so you can put the brand name in this posts title. "Buy broken BRANDNAME power supply or not?"Really.

author: Asuka
author_rank: Regular Contributor
timestamp: November 30, 2017, 12:32:04 am
content: Quote from: cdev on November 29, 2017, 11:56:44 pmIt might or it might cost next to nothing. In Japan they always give you an estimate and ask if it's OK before going ahead with repairs. Last time I got something repaired (by Makita) it cost 1,100 yen (about $11) including the transportation costs, which was about the cost of the parts, and they even polished the electrical plug.Quote from: cdev on November 29, 2017, 11:56:44 pmShop does not accept offers.Quote from: cdev on November 29, 2017, 11:56:44 pmBrand is Takasago.Quote from: cdev on November 29, 2017, 11:56:44 pmHave done as you suggest. Thanks for replying, I appreciate your taking the time.

author: Brumby
author_rank: Unknown
timestamp: November 30, 2017, 01:45:42 am
content: Quote from: Asuka on November 29, 2017, 11:39:21 amUnless you have a reason to purchase sooner than later, I might suggest this: Tell them that, for a unit that doesn't work at all, the price is too much. Let them have the opportunity to drop the price.

author: cdev
author_rank: Super Contributor
timestamp: November 30, 2017, 01:55:39 am
content: Is this it, the KX series? If so it looks like a high end externally controllable lab power supply that's likely worth a lot more than $50 working. That said, it may not be an easy repair (but it also might be). Its hard to say.http://www.takasago-ss.co.jp/english/products/power_electronics/dc/kx/kx.htmlhttp://www.takasago-ss.co.jp/products/power_electronics/dc/kx/features_kx.html

author: james_s
author_rank: Super Contributor
timestamp: November 30, 2017, 02:11:15 am
content: $50 seems much too high for a dead unit in unknown condition, IMHO let somebody else take that gamble. I might pay $20 for that in hopes of an interesting project but even then only if I had a need for it. Broken equipment is worth pennies on the dollar, if the seller wants top dollar then they should have it fixed before selling. If they won't take offers then they may be sitting on it for a very long time.

author: cdev
author_rank: Super Contributor
timestamp: November 30, 2017, 02:17:18 am
content: This is clearly a quality unit. But, don't offer their asking price. Chances are they will take less.Working it would likely be worth >$100 but not much more given that it is only a single supply.$30 seems like a good top price based on a maybe 50-50 chance of being able to fix it.I'm worried about your safety.Lets think a bit.Its so new that the most common things which typically go wrong with used equipment (such as old electrolytic capacitors giving up the ghost)are unlikely. Also, its such a high quality unit that its more likely than not it has internal safety features which simply turned it off when a dangerous condition was encountered.High quality power supplies are unlikely to just burn out because of use they encounter - for example, if I short out my Sorenson power supply it just delivers its rated power and whatever is there gets hot, but teh power supply doesnt blow up. It limits the output at whatever its set to or slightly above its rated output.Its not unlikely you will open it up to simply find a blown fuse or similar.I'm surprised there is not a fuse visible, did you check for one?Perhaps more likely is something like ESD damage. From a high voltage.Here is their big catalog.I don't speak japanese so I am basically lost - I can only guess at what they are saying.http://www.takasago-ss.co.jp/products/catalog/pwr/PSC-2017-EX13.pdfIts also possible that it is a complex unit which they simply do not know how to use.Suppose there is some jumper for example which turns on remote digital control is on, dis-activating the user controls?But then i would expect some indication it was on and under computer control. A light indicating such.Really, you need a service manual or at least somebody who speaks Japanese who can translate the catalog and make some educated guesses about what to look for.You need at least the operators manual. Which is likely on their site soewhere.Look for the service manual on Japanese geek sites.. which must exist in the Japanese web.Look here at the repair section's stickies where you will find links to several web sites where there are large numbers of manuals for equipment. Also see below for a few more (there are duplicates)http://www.eevblog.com/wiki/index.php?title=Service_manuals_and_repair_informationAnother one is electrotanya.orgif you're lucky you'll find the service manual in Japanese and it will be a PDF or something you can translate laboriously. I think thats the most optimistic scenario. Ask any Japanese friends you have if they know of any similar Japanese sites.The very best situation would be, you get it home and its something very simple. With any complicated device, there is a small but nonzero chance that it may not even be broken. Unlikely but it happens.

author: Asuka
author_rank: Regular Contributor
timestamp: November 30, 2017, 01:08:58 pm
content: Following up this post, I went to the shop and bought the power supply today. Connecting it to the power, although nothing happens it draws a few watts of power, dropping to one watt, when switched on. I opened it and cannot see any obvious faults. The fuse is in good order (tested with multimeter). The capacitors are not obviously broken. Since there is nothing which looks easy to fix or any obvious problem, and because it is actually drawing some power, I'm going to send it to the manufacturer for repairs. Someone asked for pictures so here they are. I shrank them to 25% of the original size to not break the forum's requirements.I took more photos so if anyone wants specifics let me know.Thanks everyone here. I will post again if I manage to get it fixed by Takasago.P.S. Forgot to mention I also went through the reset procedures given in the manual without success.

author: cdev
author_rank: Super Contributor
timestamp: November 30, 2017, 01:46:32 pm
content: That is a beautiful looking power supply in mint condition. I wonder what could possibly be wrong with it?Ask them if they will send you a copy of theownersandservice manual.If you can ask them in Japanese that would likely be best, but you should ask for the English manuals if available.Its been my experience with people in Asian countries that not that many people spoke English at most businesses. So it helps a lot to have a friend who can translate for you.Maybe somebody here speaks Japanese. We have had members who post here from Japan sometimes. Maybe you should post a new thread giving the name of the unit and model number and posting all the pics there, asking first if anybody has the manual, and then if anybody speaks Japanese?You should be careful to ground yourself before touching the PCB or internal connections. And maybe get a ESD mat, wrist strap, etc. for safety. Ground both properly. Treat it as you would any other piece of delicate electronics. If its cold there it is also likely to be dry which means more danger of static charges.Could you take more pictures and post some detailed pictures of the front and back panels too? Also closeups of the PC boards with enough lighting and detail to read the labels on the components. (to identify the hardware it uses) Use bright, diffuse lighting if possible. If you use flash, tape a white card or something to the flash so it bounces off a white or brightly colored object ideally a wall or ceiling before illuminating the board. That will give you a diffuse light.Start a "repair" forum thread. Give the full model and manufacturers name. Repair of T.... seeking info/manual.This power supply looks good enough to be interesting to people here and its quite possible that you will get more people reading who could help in "Repair" than "Beginners".Also there is the distant but very real possibility that somebody at the Takasago company might be able to help directly if they saw it. This forum is very popular and companies often post information here and some firms have a member of their support staff who has an official account here.It gives them exposure to a much larger potential customer base.Companies that are super helpful to people who own their products - even when second hand, have a warm spot in many of our hearts and all things being equal, I know that I try to buy them.A repair friendly manufacturer is a huge plus.Its similar with companies that try to make their products Linux friendly.I think people here would be especially likely to be able to help you in the project if you could collect all of the Japanese documentation you have access to on their web site and post links to it.Even if its in Japanese, Google Translate can translate smaller PDFs. If you have access to a web server you could even chop up a larger PDF into smaller ones and upload them, then point Google Translate at them, and save the output.

author: CJay
author_rank: Super Contributor
timestamp: November 30, 2017, 02:16:39 pm
content: That fuse holder looks rather loose...

author: Asuka
author_rank: Regular Contributor
timestamp: November 30, 2017, 11:55:32 pm
content: Quote from: cdev on November 30, 2017, 01:46:32 pmThere is a small amount of corrosion on the top visible in one of the photos, there were a few dust bunnies inside the power, and three of the case screws seem to be missing (if they were ever there).Quote from: cdev on November 30, 2017, 01:46:32 pmI have printed out the owners' manual. It's not clear there is a service manual.Quote from: cdev on November 30, 2017, 01:46:32 pmI've taken a photo of the main board but didn't attach it yesterday. I had to shrink it to 50% of the size so that it was postable to the forum.

author: Asuka
author_rank: Regular Contributor
timestamp: November 30, 2017, 11:58:27 pm
content: Quote from: CJay on November 30, 2017, 02:16:39 pmI think it's OK.

author: kalel
author_rank: Frequent Contributor
timestamp: December 01, 2017, 12:55:28 am
content: Note that if you want to post higher resolution photos, you can always use a service (free image host).Then, to show the image in forum, just click on the image button (below the "B" button) and paste the image URL between the IMG tagsCode:www.site.com/img

author: Old Don
author_rank: Regular Contributor
timestamp: December 01, 2017, 01:41:06 am
content: A different model Takasago P.S. (working) is for sale on eBay for over $200:https://www.ebay.com/i/401163818786?chn=ps

author: glarsson
author_rank: Frequent Contributor
timestamp: December 01, 2017, 06:56:49 am
content: Yes. My comment was towards the "Any good supply...", not just this power supply.

author: CJay
author_rank: Super Contributor
timestamp: December 01, 2017, 06:58:54 am
content: Quote from: Asuka on November 30, 2017, 11:58:27 pmI think you're right, it may have just been the angle, shadow etc.It looks like a really nice PSU, I hope you get it repaired, either by your own hand or by the manufacturer, would be a shame not to see it working.

author: Brumby
author_rank: Unknown
timestamp: December 01, 2017, 07:04:41 am
content: Quote from: kalel on December 01, 2017, 12:55:28 amIf they are really big images, it is better to offer the URL to the photo, rather than place it inline. Members can then choose to follow the link if they want to see the photo, whereas if it is included inline (which is what the IMG tag does) it forces every visitor to download the image. This isn't a problem for many of us with fast internet - but some members who are not so fortunate can be stuck for minutes, unless they abandon the page.

author: cdev
author_rank: Super Contributor
timestamp: December 01, 2017, 05:10:25 pm
content: I like the way they specify its output power in a "zoom" mode in watts under the curve, giving you ability to output either more voltage and less current or more current and less voltage?This is a capability most bench supplies only give you by adding or strapping separate outputs together.

author: Jwillis
author_rank: Super Contributor
timestamp: December 03, 2017, 02:27:27 am
content: Hard to see,but then I'm halve blind anyway.I think maybe but could be wrong.HD64F7051F20 is a 32 bit micro controller.HC08 is a Quadruple 2-Input Positive-AND GatesHC14 are Hex Schmitt-Trigger Invertersso most of that side of the board is for interfacing and digital readout.The right side of board I can make out four op amps OP191 for supply control and protection.AD8842 which may be part of the voltage adjustment.Not sure if the unit powers up at all or is completely dead.If its totally dead then I would start at the AC in and work from there.

author: Asuka
author_rank: Regular Contributor
timestamp: December 04, 2017, 08:45:38 am
content: A final note on this thread. I contacted the manufacturer by phone today and spoke to a repair person. According to the person I spoke to, the serial number of the unit indicates a construction date of 2007, and this model is at the end of its life with manufacture set to end in March 2018. If I send it back for repair, it will cost nearly as much as a new unit, because to repair a 2007 unit they would have to replace the internals with the current spec components ("overhaul"). That means I have to either repair it myself or get rid of it. I'm not really set up for repairing it yet but my plan is to keep hold of the unit and try to get it repaired by December 2018, failing that I'll scrap it or sell it on Auctions or something. When I try the repairs, what I'll do is post on the repair forum as suggested by CJay above rather than on this thread. I probably won't start doing that until next year, so I'll see you then. I had quite a good conversation with the repair person, who suggested that the problem was almost certainly in the power supply part.Thanks to everyone who's replied here.

author: Old Printer
author_rank: Frequent Contributor
timestamp: December 04, 2017, 05:02:22 pm
content: As the years go by things like this are becoming more difficult to impossible to repair. So many of the fine pitch components are all but impossible to remove and replace. As things like FPGA's become predominant even the manufacturers can't or don't want to work on then other than replace boards. Buying used gear is getting to be a real gamble. I bought 2 "working" Analog Discovery's from the same dealer on ebay, neither worked and Digilent was as helpful as they could be, but they don't even repair what they sell. I got lucky and the seller refunded me, but buyer beware now more than ever. I finally ponyed up the $$ and bought a new one with the factory guarantee.

author: cybermaus
author_rank: Frequent Contributor
timestamp: December 04, 2017, 07:01:17 pm
content: Well, that depends of course. If its the brain box, it will be difficult.But it can still be the power supply. High-res photos and a schematic is what is needed to assist with pointing out what to measure with a simple DMM to see if at least the right base voltages exists.

author: cdev
author_rank: Super Contributor
timestamp: December 04, 2017, 11:29:54 pm
content: Did you ask him about a service manual?A service manual will give you an order of battle.. check A voltage, if voltage >n check B, if not check C and so on...Quote from: Asuka on December 04, 2017, 08:45:38 am

author: james_s
author_rank: Super Contributor
timestamp: December 04, 2017, 11:38:40 pm
content: This is pretty much what I expected would happen, and the reason I mention my policy of paying very little if anything for broken gear. Too much of it is just not economical to repair unless one is persistent, has a lot of free time and some luck.

author: Asuka
author_rank: Regular Contributor
timestamp: December 06, 2017, 06:37:40 am
content: Quote from: cybermaus on December 04, 2017, 07:01:17 pmThe person I spoke to on the phone seemed fairly sure about that.Quote from: cybermaus on December 04, 2017, 07:01:17 pmThanks, I will be back next year (January 2018) with high resolution photos. I'll set up an account on imgur or similar since they cannot be posted here.

author: cdev
author_rank: Super Contributor
timestamp: December 06, 2017, 11:42:09 pm
content: You can post up to 2 Mb per post which is a LOT if you compress images intelligently. Download a copy of theGimp, ( gimp.org ) and fool around a bit with the image compression settings for jpg and png.

author: CJay
author_rank: Super Contributor
timestamp: December 07, 2017, 06:25:39 am
content: Quote from: cdev on December 06, 2017, 11:42:09 pmOr Irfanview which has a very nice 'save for web' option in the file menu

author: GreyWoolfe
author_rank: Unknown
timestamp: December 07, 2017, 01:01:32 pm
content: Quote from: CJay on December 07, 2017, 06:25:39 am+1 for Irfanview. I use it regularly, not just here but for any images I need to send/post anywhere. I also have it on my company laptop. Great program that's easy to use.

author: Seekonk
author_rank: Super Contributor
timestamp: December 07, 2017, 01:40:31 pm
content: Hate to see you just give up. Don't think you have said what exactly is wrong with the unit. Does the display power up at all? If it doesn't this is probably a very easy problem to diagnose. Who needs schematics. Form follows function.

author: Decoman
author_rank: Regular Contributor
timestamp: December 07, 2017, 01:47:52 pm
content: At the risk of sounding off topic:For better processing photos and sometimes images, I use the free-to-download Fusion 8 (it was free when i downloaded it from the devs, blackmagicdesign) This is a node based compositing software for movies/tv, but works great for:1) scaling down photos (because you don't want to upload 3MB huge .jpg's, and sometimes photoshop isn't good enough for scaling down photos)2) and in the node, apply sampling filter of choice, from very sharp to more blurry (whatever happens to look the best in any case)3) color correction (fun to remove/suppress color, very simple to do)4) adjust gamma, brightness and bunch of other things with one node5) output as .jpg image with a reasonable file sizeLearning to use this software might have you scratch your head in the beginning, but once you know how, you can save your setup, and reuse it for your next photo or whatever.

author: xani
author_rank: Frequent Contributor
timestamp: December 07, 2017, 05:50:14 pm
content: Downloading Fusion just to scale some pictures is like using scope as a multimeter

author: Seekonk
author_rank: Super Contributor
timestamp: December 07, 2017, 08:03:45 pm
content: I have a firm belief that people that feel the need to post high resolution photos have no chance of fixing anything. They are a crutch for those that don't want to go through the logical process to diagnosis the problem. I won't help those who just clog up posts with meaningless crap.

author: cdev
author_rank: Super Contributor
timestamp: December 08, 2017, 12:37:02 am
content: 2Mb per image will still give you a hell of a large and detailed image if you compress it intelligently.

author: nanofrog
author_rank: Super Contributor
timestamp: December 08, 2017, 01:30:45 am
content: Quote from: Asuka on December 06, 2017, 06:37:40 amFWIW, you don't have to create an account with imgur just to upload and post the image.

author: Awesome14
author_rank: Regular Contributor
timestamp: December 08, 2017, 05:19:43 am
content: Just another form of gambling, or treasure hunting. It's worth it if it's any easy fix. But if the transformer is open, you lose.

author: CJay
author_rank: Super Contributor
timestamp: December 08, 2017, 09:07:36 am
content: Quote from: Awesome14 on December 08, 2017, 05:19:43 amIt's a gamble, yes, but the odds are stacked in favour of the gambler, especially if they have the help of a forum like this and a modicum of sense.Plus, every repair gives you the opportunity to learn something even if you don't get a functioning device at the end of it so it's never a losing proposition if you're doing it for hobby/education.

author: Seekonk
author_rank: Super Contributor
timestamp: December 08, 2017, 11:57:17 am
content: Quote from: blueskull on December 08, 2017, 12:32:40 amI almost think the internet is a hindrance to learning electronics. When I learned electronics there was no internet and no one to talk to, I had to read and experiment. The OP seems to have done is deprive this supply from someone that could use it. He has just given up at not finding a bad fuse. Uploading detailed pictures just screams of fix this for me while I sit back. I have no interest in tracing out boards over the internet. I understand that it is easy to look at a mass of parts and think it is just black magic. Diagnosis is an art. You make a list of what you know and what you don't know about the problem. A power supply is just made up of a bunch of simple blocks. It is a logic chain you work through. A bad photo tells you enough, look in this section. Don't think the OP has detailed the problem beyond "It's broken." The OP needs to step up and approach this logically.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 08, 2017, 12:49:57 pm
content: Quote from: Seekonk on December 08, 2017, 11:57:17 amThe beauty of learning to troubleshoot is that it's a universal skill. If you can troubleshoot one thing, you can troubleshoot another. Though it helps to have specific knowledge on the subject, it's not actually needed to get anywhere.

author: CJay
author_rank: Super Contributor
timestamp: December 08, 2017, 02:28:56 pm
content: Quote from: Seekonk on December 08, 2017, 11:57:17 amI think it's often used as a quick fix for those who can't be bothered, seen it here a lot, people who want physics to be how they decide it has to be, people who think it's too geeky to learn so they come find the geeks and ask them, then you get the posts where everyone joins in with a dozen different theories which just serve to confuse the OP and cause arguments.Then there are threads like the 386 motherboard thread or the building my own Z80 SBC thread which are works of beauty, complete end to end solutions (that's not to say there aren't other threads that are, they're just the recent ones I've seen) or other threads where it's obvious almost immediately that the OP is genuinely keen and interested, they all make the time waster threads worth putting up with.The main barrier to learning electronics is the person who is trying to learn, if they don't want to or just aren't able to learn the subject then they just won't, it doesn't matter how many people try to help them.

author: cdev
author_rank: Super Contributor
timestamp: December 08, 2017, 04:13:42 pm
content: These two posts capture the essence of the process for me too. You don't need to know everything there is to know about something.First you collect information on what is happening when power is applied with your DMM and compare it to what is supposed to happen as laid out in the datasheets for its individual parts. You can also make some additional tools . Since your board is a switching power supply, be careful.As it has at least one microprocessor on it, you will want to see if the microprocessor(s) has any "heart beat". This may not be as easy without an oscilloscope as it would be with one. Especially, watch out for high voltages. If you plan on doing electronics a lot, try to find a deal on an older scope.That will give you a good start on it. Keep in mind the sage advice to doctors. "First do no harm". Don't break anything additional. Use common sense and think when probing the board. Measuring voltages properly is unlikely to cause any damage. Check if voltages that are supposed to power various parts are even there. If they are not, its likely there is your problem.Even parts that are soldered to a PCB are replaceable. Just watch how Louis Rossman does i in his Youtube videos. (To do that you will need to invest in tools to do it but they are not so super expensive that its difficult. Several tools that work well, either alone or combined with your regular soldering iron are a digital hot plate for preheating, a controlled temperature hot air gun, and ChipQuik: low melting point solder for removing SMD parts, all individually can be quite cheap)If you fix it - every time you use it you'll get a jolt of satisfaction from having done it.Quote from: Mr. Scram on December 08, 2017, 12:49:57 pm

author: Asuka
author_rank: Regular Contributor
timestamp: December 09, 2017, 01:06:53 am
content: Quote from: Seekonk on December 07, 2017, 01:40:31 pmI have not given up. I'll post again in January 2018.

author: massivephoton
author_rank: Contributor
timestamp: January 13, 2018, 08:01:47 pm
content: Quote from: Asuka on November 30, 2017, 11:55:32 pmCould that green wire connecting Pin 8 of CN2 to what looks like a smd resistor indicate it was repaired earlier?If so, this could hint what was wrong.It's already 2018, time for another try!

author: Asuka
author_rank: Regular Contributor
timestamp: January 14, 2018, 12:03:44 am
content: Quote from: massivephoton on January 13, 2018, 08:01:47 pmIt might be that, but I can think of other explanations. For example, this is one of a range of models, so to save manufacturing cost, all the models use the same control circuit board, then they solder a wire between two points after the manufacture of the board to indicate to the board what particular power board it is controlling.Quote from: massivephoton on January 13, 2018, 08:01:47 pmI'll post something before the end of January, as promised above.