Problem with meanwell power supply knock off.

[dogman dan]

Firstly, on Ebay, Best eletronics store in Booklyn NW does not sell the real MW power supply, though the page shows specs for meanwell models.

This is model SP-350 from an ugknown manufacturer.



Click on the photo to enlage. The problem item looks like a disk of graphite or something. Right under the fuse in the photo. Has a zig zag line on the board there, along with a circle

If I can source one, this looks big enough for even me to see it and solder a new one.

 

[commanda]

I'd hazard a guess that was a thermistor. NTC ?
Used to limit the inrush current at switch on. Salvage a replacement from a dead PC power supply.

Amanda

 

[torker]

Yea, looks like it should be a resistor of some sort.

 

[docnjoj]

Hey dogman. The blue disc on the left of the yellow boxlike doohicky seems to have the same symbol so that is about the size thermistor you are looking for. Maybe you can see some numbers on it?
otherDoc

 

[dogman dan]

I guess it's definitely a resistor. It say NTC1 next to it, but I wasn't sure if that was for the fuse or the burnt part.

Wierd thing though, two wires and a graphite looking disk, no potting.

Removing the backside, it's the first thing on the board from the white, neutral , AC wire.

 

[commanda]

If it say's NTC1 next to it, then it is definitely a Thermistor. Temperature dependent resistor. Negative Temperature Co-efficient. Starts off high resistance which limits the inrush current. Current flowing through it causes it to warm up, which lowers the resistance.

 

[dogman dan]

Nice, I suppose it's not really manatory that it has one? Just there to make it last longer, :lol: .

Got a real meanwell on the way btw.

 

[wineboyrider]

Got a real meanwell on the way btw.

Fleabay?

 

[dogman dan]

Yeah fleabay again, but this time it should be the real McCoy.

Apparantly the old one does still work if I jumper the legs on the busted thermistor. Went to mouser, but pretty bewildering. Found similar looking part, but not sure which one I need. Others called NTC 1 look different. Out of my knowledge range for sure.

I'm inclined to solder the jumper on permanent, and let er rip. I use it on the fireplace hearth after all.

 

[dogman dan]

Works for a few minuites jumpered, then quits. Works again if plugged in later, but only for a miniute at a time.

This thing is junk not worth any more time. From day one, if you bumped it, it would disconnect. Other parts in it are also from the cheap parts bin, AKA trashcan.

 

[dnmun]

it is called an inrush current limiter, ICL, a Negative Temperature Coefficient thermistor. that label is the sign for a thermistor.

you can look in mouser for ICL, 5 ohm, and at least 6A capacity to fix your charger. it's not junk, just broken and can be fixed easily.

i have now sold 18 of the 6.3A ICLs i bot from mouser last year, and restored about 10 chargers to active and long lives.

just sold two to curtis, for $4 total, in the mail this morning. i think you will find they cost about $2.40 each from mouser now, before you pay for shipping.

 

[wineboyrider]

I'm inclined to solder the jumper on permanent, and let er rip. I use it on the fireplace hearth after all.

LOL! LMAO! You have that New Mexican attitude! I feel the same way too sometimes. You pay money for something you want to do and some little teeny tiny piece of crap gets in the way! 8) 8) 8) 8) 8)

 

[amberwolf]

If you have any not-in-use power bricks for things laying around, maybe even PC power supplies, there's a decent chance that the part you need is in those. TV sets often also have them, so any old attic clunker could have just what you need.

 

[dogman dan]

Yeah, I'll give a look when I see those TV's dumped in the desert.

I looked at mouser, and just couldn't figure out which one was the correct thing. It sure doesn't work right without it, but it sorta was doing that before so, it may be a bit worse than just the obviously fried part.

 

[wineboyrider]

If you have any not-in-use power bricks for things laying around, maybe even PC power supplies, there's a decent chance that the part you need is in those. TV sets often also have them, so any old attic clunker could have just what you need

Hey Amberwolf how many watts does a usual PC power supply have?? I've got a couple of old PC's that in my attic somewhere that I never got around to fixing. Hehe.

 

[dnmun]

inrush current limiters are used in the switch mode power supplies, not the older 60hz type.

the ones i sell are mouser pt # 871-B57238S509M and it appears they are only 94 cents. thought they were a lot more.

http://www.mouser.com/ProductDetail/EPCOS/B57238S509M/?qs=sGAEpiMZZMv9eKVyXEc%252bhAZUpToxTU3SpO82dYgKgFg%3d

 

[torqueon]

it is called an inrush current limiter, ICL, a Negative Temperature Coefficient thermistor. that label is the sign for a thermistor.

you can look in mouser for ICL, 5 ohm, and at least 6A capacity to fix your charger. it's not junk, just broken and can be fixed easily.

i have now sold 18 of the 6.3A ICLs i bot from mouser last year, and restored about 10 chargers to active and long lives.

just sold two to curtis, for $4 total, in the mail this morning. i think you will find they cost about $2.40 each from mouser now, before you pay for shipping.

Do you think those Ebay china knock off are any good

 

[dnmun]

i don't know what you are talking about on ebay. the only problem with the ICLs used in these small chargers is that the ICL is too small for the current required by the front end of the SMPS. it is not a problem of manufactured in china, since everything is made there now. these are actually very sophisticated devices, a good use of rare earth elements which china produces more of than everyone else too. i have tried to help a buncha people beyond the ones i sold already but most people just don't wanna fix stuff and think buying a new charger is the easiest solution. it is the american way. waste away.

 

[torqueon]

i don't know what you are talking about on ebay. the only problem with the ICLs used in these small chargers is that the ICL is too small for the current required by the front end of the SMPS. it is not a problem of manufactured in china, since everything is made there now. these are actually very sophisticated devices, a good use of rare earth elements which china produces more of than everyone else too. i have tried to help a buncha people beyond the ones i sold already but most people just don't wanna fix stuff and think buying a new charger is the easiest solution. it is the american way. waste away.

Was refering all the mean well look alike suppies i see on ebay for $ 20 to $ 40

Thank you

 

[amberwolf]

Hey Amberwolf how many watts does a usual PC power supply have?? I've got a couple of old PC's that in my attic somewhere that I never got around to fixing. Hehe.

I dunno what NTC ratings might be, but the power supply output ratings vary quite a bit, from 80W on the tiny "pizza box" PCs all the way up to over 1KW on some of the high-end gaming or server systems, multicore machines, etc.


In the really old TV sets, I've found NTCs controlling the degaussing circuit sometimes. Never reverse-engineered it, so not sure exactly how they are doing it, and I don't know the ratings but worth a look. There are also usually a lot of other good parts in there, even on the non-switching-PSU types. Nowadays, even the 20-30-year old TVs many consider clunkers are still pretty modern in design, using switching PSUs in them (someimtes on the larger ones it's on a separate board, meaning you can take it out and use it for something else!).


Whenever I see TVs or other things in the alleys, they typically have already been smashed by vandals, but I still take the PCBs home and usually torch-desolder all the parts into a bin. Most of them are perfectly good, even after that, and have repaired hundreds of other things for me.

 

[dnmun]

i do the same thing, i have buckets of small parts, taken from radios and tvs and old cordless drill chargers. you can estimate the power capacity by looking at the diameter of the ICL. if it is 12mm or so then about 3-4A and around 15mm it is 4-5A then 18mm like mine are 6-7A and then the larger ones around 19mm are 8A and then 21mm is about 10A. they need more material to dissipate the heat. the resistance drops to about .2ohm as it gets hot so it has to handle about 3-4W of heat while running. you can tell if it is too small when you can see the pcb is burned underneath.

new is always better in parts like this though, since they are fragile after they have baked a few times i suspect. jmho.

 

[dogman dan]

FWIW, I found a dead charger and took a similar resistor out of it, but then the fake meanwell still acts the same as before. Turns on, runs for a few min, then starts malfunctioning. High pitched squealing like sound coming from the other end of the box. Very faint, can hardly hear it. Sounds like coming from some big fets there. something else is not working.

So once again, simple fix too much for dogman.

 

[torker]

Might have to try an old computer supply like I did and maybe research the fix on that one a bit more. There are tons of those in the 150 to 250 watt range and free if you know where to look-Freecycle maybe.

 

[wineboyrider]

@dnmun and @ amberwolf:
It's not that I don't like to reuse or repair anything, but I wouldn't know what the hell most of that stuff is by looking at it. Although, I know a little bit more than before. Kind of wish I had studied electronics in the Army instead of Nuclear weapons.hehehe. 8)

 

[amberwolf]

It's not that I don't like to reuse or repair anything, but I wouldn't know what the hell most of that stuff is by looking at it. Although, I know a little bit more than before.

I learn lots of stuff by doing...and breaking. But if it is broken to start with, I don't have much to lose but time. Time costs a lot less than money to pay someone to fix it or to buy a new one, for me, though this isnt' true of everyone.

FWIW, I found a dead charger and took a similar resistor out of it, but then the fake meanwell still acts the same as before. Turns on, runs for a few min, then starts malfunctioning. High pitched squealing like sound coming from the other end of the box. Very faint, can hardly hear it. Sounds like coming from some big fets there. something else is not working.

Maybe one of the caps is failing after either A) the voltage rises enough or B) it gets hot enough. Can you get any pics of the whole thing with a slight angle across the top, so we can see if any caps look swollen relative to others? (sometimes bad caps dont' swell visibly, though, having leaked electrolyte out the bottom instead, someitmes invisibly)