Author Topic: Buy broken Takasago power supply or not?  (Read 1629 times)

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Offline Asuka

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Buy broken Takasago power supply or not?
« on: November 29, 2017, 07:26:43 PM »
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.


« Last Edit: November 30, 2017, 11:26:27 AM by Asuka »
 

Online ataradov

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Re: Buy broken power supply or not?
« Reply #1 on: November 29, 2017, 08:50:47 PM »
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.
« Last Edit: November 29, 2017, 08:54:05 PM by ataradov »
Alex
 
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Offline wilfred

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Re: Buy broken power supply or not?
« Reply #2 on: November 29, 2017, 09:33:11 PM »
Did the shop already know it didn't work when they put a 5000yen price on it?  If not then offer them 2000yen. Don't die wondering.

But also don't die trying to repair it. With switching power supplies it is best to have some idea of the dangers.
 
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Offline Asuka

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Re: Buy broken power supply or not?
« Reply #3 on: November 29, 2017, 10:39:21 PM »
Thanks for replying, I appreciate it.
Did the shop already know it didn't work when they put a 5000yen price on it?
They know it doesn't work at all.
Quote from: wilfred
If not then offer them 2000yen. Don't die wondering.
The shop doesn't accept offers. There is a sign telling people not to make offers.
Quote from: wilfred
But also don't die trying to repair it. With switching power supplies it is best to have some idea of the dangers.
I'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.



« Last Edit: November 30, 2017, 10:36:22 AM by Asuka »
 

Offline kalel

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Re: Buy broken power supply or not?
« Reply #4 on: November 30, 2017, 01:38:40 AM »
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, you might have 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.
« Last Edit: November 30, 2017, 01:41:50 AM by kalel »
 
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Offline CJay

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Re: Buy broken power supply or not?
« Reply #5 on: November 30, 2017, 01:41:15 AM »
Thanks for replying, I appreciate it.
Did the shop already know it didn't work when they put a 5000yen price on it?
They know it doesn't work at all.
Quote from: wilfred
If not then offer them 2000yen. Don't die wondering.
The shop doesn't accept offers. It's a Japanese shop but there is a sign in English telling people not to make offers.
Quote from: wilfred
But also don't die trying to repair it. With switching power supplies it is best to have some idea of the dangers.
I'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.

Switch 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
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Online rstofer

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Re: Buy broken power supply or not?
« Reply #6 on: November 30, 2017, 01:50:49 AM »
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.

 
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Offline 3db

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Re: Buy broken power supply or not?
« Reply #7 on: November 30, 2017, 01:57:08 AM »
I would buy it anyway.
You could most likely sell it in its current condition for more than you'll pay for it.
 
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Offline cybermaus

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Re: Buy broken power supply or not?
« Reply #8 on: November 30, 2017, 02:24:54 AM »
I would buy it anyway.
You could most likely sell it in its current condition for more than you'll pay for it.

A 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.



 
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Offline cdev

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Re: Buy broken power supply or not?
« Reply #9 on: November 30, 2017, 04:50:32 AM »
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.

« Last Edit: November 30, 2017, 11:17:06 AM by cdev »
"What the large print giveth, the small print taketh away."
 
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Offline Seekonk

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Re: Buy broken power supply or not?
« Reply #10 on: November 30, 2017, 07:52:06 AM »
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.
 
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Offline glarsson

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Re: Buy broken power supply or not?
« Reply #11 on: November 30, 2017, 08:05:55 AM »
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.
Unfortunately, this does not work for switching power supplies with a PFC circuit.
 
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Offline Asuka

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Re: Buy broken power supply or not?
« Reply #12 on: November 30, 2017, 10:04:35 AM »
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.
The person who sold it to the second-hand shop might have done that, but the shop definitely did not attempt any repairs.

 

Offline Terry01

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Re: Buy broken power supply or not?
« Reply #13 on: November 30, 2017, 10:16:52 AM »
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!  :wtf:

Good luck however you go.
Sparks and Smoke means i'm nearly there! 8)
 
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Offline Asuka

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Re: Buy broken power supply or not?
« Reply #14 on: November 30, 2017, 10:52:42 AM »
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!  :wtf:
A 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.
Good luck however you go.
Thanks. 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.
 

Offline cdev

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Re: Buy broken power supply or not?
« Reply #15 on: November 30, 2017, 10:56:44 AM »
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 a service manual? Is it a quality brand? It looks like it might be 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.
« Last Edit: November 30, 2017, 11:14:40 AM by cdev »
"What the large print giveth, the small print taketh away."
 
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Offline Asuka

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Re: Buy broken power supply or not?
« Reply #16 on: November 30, 2017, 11:32:04 AM »
Sending it back to manufacturer may cost a LOT.
It 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.
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.
Shop does not accept offers.
Have you looked at the sites listed in the wiki here for a service manual? Is it a quality brand? It looks like it might be a quality supply, but you never know, if its an unknown brand.
Brand is Takasago.
You should edit the thread name so you can put the brand name in this posts title. "Buy broken BRANDNAME power supply or not?"
Have done as you suggest. Thanks for replying, I appreciate your taking the time.
 
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Offline blueskull

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Re: Buy broken Takasago power supply or not?
« Reply #17 on: November 30, 2017, 11:51:54 AM »
I would take it if I have a chance. For $50, even if you can't fix it, it will be a fun journey to troubleshoot this thing.
Of course, you must have an idea whenever you work on high voltage, high energy stuffs. Safety first.

As for how hard it will be to fix it, it all depends. It could be a dead fuse/NTC/MOV, or slightly harder, a dead MOSFET or a dead diode bridge or some aged caps. It could also be a fried MODFET took out its controller and other chips as well.
The third case is almost non-repairable, especially if the controller is a digital one running custom firmware. The second case requires some patience, and the first case is basically the moment of "I scored!".
SIGSEGV is inevitable if you try to talk more than you know. If I say gibberish, keep in mind that my license plate is SIGSEGV.
 
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Offline Brumby

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Re: Buy broken power supply or not?
« Reply #18 on: November 30, 2017, 12:45:42 PM »

The shop doesn't accept offers. There is a sign telling people not to make offers.


Unless 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.
 
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Offline cdev

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Re: Buy broken Takasago power supply or not?
« Reply #19 on: November 30, 2017, 12:55:39 PM »
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.html

http://www.takasago-ss.co.jp/products/power_electronics/dc/kx/features_kx.html
« Last Edit: November 30, 2017, 01:09:13 PM by cdev »
"What the large print giveth, the small print taketh away."
 
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Online james_s

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Re: Buy broken Takasago power supply or not?
« Reply #20 on: November 30, 2017, 01:11:15 PM »
$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.
 
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Offline cdev

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Re: Buy broken Takasago power supply or not?
« Reply #21 on: November 30, 2017, 01:17:18 PM »
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.pdf


Its 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_information

Another one is electrotanya.org

if 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.
« Last Edit: November 30, 2017, 02:05:57 PM by cdev »
"What the large print giveth, the small print taketh away."
 
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Offline Asuka

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Re: Buy broken Takasago power supply or not?
« Reply #22 on: December 01, 2017, 12:08:58 AM »
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.
« Last Edit: December 01, 2017, 12:17:18 AM by Asuka »
 

Offline cdev

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Re: Buy broken Takasago power supply or not?
« Reply #23 on: December 01, 2017, 12:46:32 AM »
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 the owners and service 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.
« Last Edit: December 01, 2017, 01:02:20 AM by cdev »
"What the large print giveth, the small print taketh away."
 
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Offline CJay

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Re: Buy broken Takasago power supply or not?
« Reply #24 on: December 01, 2017, 01:16:39 AM »
That fuse holder looks rather loose...
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