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#1 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() Good day folks. It's been a while since I've fixed a PSU and it shows with this one, as I can't seem to figure out how it works and what's wrong with it.
Fuse was open (though not obliterated) and the two transistors shown were shorted. The originals pictured up-close are AP50WN1K5I and I couldn't find the exact match. They looked pretty standard in terms of specs, so the guy at the store looked over some datasheets and gave me two FQPF6N60C instead. The datasheets are indeed pretty close, except the replacement ones are a bit more resistive. I though it wouldn't be a deal-breaker and would work first-try...unfortunately it didn't... No catastrophic failure occurred but I got no boosted voltage on the main cap (stuck at 325v) and I got no output at all...after trying it a second time, I think I saw some smoke coming out. I couldn't see where it came from, since I quickly unplugged...I managed to quickly measure the AUX winding to see if the control IC, a TEA19161T gets VCC, but the winding is dead.... I measured the gate drive portion of both trannies and ironically everything checks out fine, so again, it could be that smoke was just my imagination, ALTHOUGH: I removed the trannies again to see if they died and the answer is "sort-of", meaning they're not dead-shorted, but one of them measures weird. Get this: I put them side by side and used my meter in diode-mode:
This is a strange PSU: it's only got a 12v output, yet it still has a green "PS_ON" wire.....how does this work ? The yellow wires are all bunched together, so how can there possibly be a "stand-by" voltage ? Even if 12v WERE the standby voltage and were on all the time, what's the purpose of the green wire then ??? It could be it's just the color that's similar, but in reality it could be a power-good signal...I was hoping I could replace the supply entirely with a 12v one, but it will be missing this signal and refuse to turn on......really sucks this one :|
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Wattevah... |
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#2 |
Badcaps Veteran
Join Date: Apr 2011
Posts: 297
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![]() Hello
Due to previous experience , i never replace chopper F E T S , without replacing the control chip also , as well as checking all the surrounding components . I have repaired many power supplies & found this to be the most reliable way to prevent failure . I also use a v a r i a c , after repair , to very gradually increase the AC supply , in case there still is an issue with board , as it can prevent additional damage from ocuring . |
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#3 | |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() Quote:
UPDATE: PC works with just 12v going into it - I hacked a 6p connector and used a regular ATX supply to power it and the PC booted fine, so the idea of hacking a MeanWell in there is becoming doable... |
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#4 | |
Badcaps Veteran
Join Date: Jul 2011
City & State: Some times Sunny Jacksonville FL
My Country: USA
Line Voltage: 120 Volts 60 HZ
I'm a: Knowledge Seeker
Posts: 3,656
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![]() Quote:
I have found that MeanWell switching power supply are very well built and most of the time they use brand name capacitors already and you do not have recap them
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9 PC LCD Monitor 6 LCD Flat Screen TV 30 Desk Top Switching Power Supply 10 Battery Charger Switching Power Supply for Power Tool 6 18v Lithium Battery Power Boards for Tool Battery Packs 1 XBox 360 Switching Power Supply and M Board 25 Servo Drives 220/460 3 Phase 6 De-soldering Station Switching Power Supply 1 Power Supply 1 Dell Mother Board 15 Computer Power Supply 1 HP Printer Supply & Control Board * lighting finished it * These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10% 1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later ) 2 Hem Saw Computer Stack Board All of these had ![]() All of the mosfet that are taken out by bad caps ![]() |
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#5 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() I found a "bare" supply from MeanWell which fits inside the metal case of this one with room to spare and even seems to match the fan and AC connectors. I was going to mount this on some stand-offs in place of this board so the whole assembly still fits inside the case like before. Everything was going well except these chaps told me it's too expensive, so it looks like I'll try swapping the TEA IC too...maybe they'll give in and eventually go with my idea
![]() The only caveat is the fan would run non-stop which will surely make some folks uneasy ![]() Last edited by Dannyx; 01-13-2021 at 01:23 PM.. |
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#6 |
Badcaps Veteran
Join Date: Jul 2011
City & State: Some times Sunny Jacksonville FL
My Country: USA
Line Voltage: 120 Volts 60 HZ
I'm a: Knowledge Seeker
Posts: 3,656
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![]() Why not use a temperature controller for the fan and put the sensor on the heat sink if it has one and if not then mount the sensor on the device that would have the most heat coming from it
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#7 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() That would be the "ideal" solution, but where does one obtain a fan controller ? I think I actually ripped some out of ATX supplies - they're small standalone boards with an NTC sticking out of it. I'd still need the PNP to turn it on/off...
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#8 |
Badcaps Veteran
Join Date: Jul 2011
City & State: Some times Sunny Jacksonville FL
My Country: USA
Line Voltage: 120 Volts 60 HZ
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Posts: 3,656
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![]() If you get one out of an ATX switching power supply some of have a small circuit board that controls the fan and all it requires is 12 volts and the use of the fan that it is hooked to
FSP 300 ( ATX ) switching power supply have a small circuit control board and easy to use You can also find them on eBay as well Last edited by sam_sam_sam; 01-13-2021 at 03:46 PM.. |
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#9 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() I think I'll need something like this to toggle the fan on and off with the PC (with or without temperature control). The 3.3v is the MB's PS_ON pin of the 6P connector which runs to the PSU. Must admit I haven't done any calculations to work out the value of R1 and R2, assuming the two trannies are 2n2222 which I have on hand currently....and what the current draw of the fan is - they may not be able to handle that much current, even though it's a relatively small fan...
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#10 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() Ok, I tried the two-transistor setup in the schematic just for a proof of concept test and it worked......not well enough though: it worked when I tested the setup on an ordinary ATX supply and powered Q1 from the 3.3v rail and Q2 and the fan from the 12v rail, but once I tried the same setup, but wit the 3.3v signal provided by the PS_ON pin of the Lenovo, it no longer worked. The fan turned off alright, as it was supposed to, but also the voltage on the pin itself dropped to nearly 0 and the PC tried firing up as well, which makes sense, since the same thing happens if you ground that pin on a regular ATX....
I think the problem is the pin can't source any current, so any slight load is too much. With this in mind, I tried a FET in place of Q1 and I used whatever I had on hand, which was a FQP6N60C. Same exact setup, except this time I also added a 10k resistor between G and S. It still didn't work: the fan didn't turn off at all this time when I applied 3.3v to the gate of Q1, hinting the D-S junction wasn't closing enough to pull the base of Q2 to GND. It was getting rather late and I was running out of ideas at this stage, so I didn't investigate further. Could be a bad choice of FET or it might be dead and won't open, since I just grabbed it off my desk. It's actually one of the two I used as replacements when trying to fix the PSU in the first place - the one with the "normal" D-S drop when turned on, as opposed to its buddy which has a 1v drop. I don't know a lot about FETs as switches, but isn't an N-channel supposed to open when the voltage at the Gate is greater than the source and draw very little current on the G pin ? Assuming my S was GND and I had 3.3v on G.... |
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#11 |
Badcaps Veteran
Join Date: Jul 2011
City & State: Some times Sunny Jacksonville FL
My Country: USA
Line Voltage: 120 Volts 60 HZ
I'm a: Knowledge Seeker
Posts: 3,656
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![]() Why not use a optic sensor like a 4N25 or something similar to this type of device
Last edited by sam_sam_sam; 01-19-2021 at 03:45 PM.. |
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#12 |
HC Overclocker
Join Date: Jul 2012
City & State: Singapore
My Country: Singapore
Line Voltage: 240VAC 50Hz
I'm a: Hobbyist Tech
Posts: 2,940
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![]() u cant use the ps_on pin of a computer psu as a power source or current source. it wasnt designed for that purpose and it wont work. u have to find somewhere else to source your 3.3v supply. i also tried the same thing before as u and i also couldnt get it to work. the ps_on pin just isnt designed for that.
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#13 | ||
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() Quote:
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#14 | |
master hoarder
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 10,860
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![]() Instead of 10 KOhms for R1, try 100-330 KOhms. Since Q1 only needs to pull about 1.2 mA of current through R2 and knowing that the current gain on these 2n2222 transistors is at least about 100 usually, then the Base current at Q1 could be approximately 100 times smaller - i.e. 10 uA or more should work. Actually, I imagine even less would work, but it would be nice to have a bit of "headroom". If the PS-ON signal still can't source that much current, you might need to go with an op-amp or comparator circuit.
Quote:
When voltage between Gate and Source exceeds the specified Vgs threshold voltage in the datasheet, the MOSFET will conduct between Drain and Source. For good conduction, Vgs > Vd. Otherwise, MOSFET may run in linear/Triode region. Same applies to P-ch MOSFETs, except all voltages should be the negatives of the values specified for N-ch.. Last edited by momaka; 01-20-2021 at 11:24 PM.. |
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#15 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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![]() That schematic was done mostly to show the layout of the components - as mentioned there, the values were not known at that time. I DID go with lower values for R1 and did the math at the time, but it didn't work - pin just can't source the current apparently. It drops to the point where the board actually tries to come on.
Time scarce and the budget must be kept as low as possible (as always), so there's no reason to push forward - I scrapped the idea and just ran two wires to the SATA power connector for the hard drive, since it comes on and off with the system. It's on a separate lead which plugs into the motherboard, so it's switched. The PSU itself has no SATA or Molex connectors at all for that matter - just a standard 4p for the CPU and a 6p, which in reality only uses 5 pins, including that green PS_ON wire which I was going to try and tap into... ![]() |
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#16 | ||
master hoarder
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 10,860
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![]() Quote:
Quote:
![]() While at it, you should just have wired the PSU fan to the 12V rail on the SATA connector. That way, when system comes on and power goes to SATA, it also goes to fan. No transistor circuits needed anymore! ![]() Last edited by momaka; 01-21-2021 at 12:04 AM.. |
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#17 |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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#18 |
master hoarder
Join Date: May 2008
City & State: VA (NoVA)
My Country: U.S.A.
Line Voltage: 120 VAC, 60 Hz
I'm a: Hobbyist Tech
Posts: 10,860
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![]() ^ Oh.... right you did.
For some reason, I read it that you just took 3.3V from the SATA power connector to drive that transistor circuit. Yeah, NVM then. Simplicity Level 300 achieved! ![]() |
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#19 | |
CertifiedAxhole
Join Date: Aug 2016
City & State: Constanta
My Country: Romania
Line Voltage: 230VAC 50Hz
I'm a: Hardcore Geek
Posts: 3,277
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#20 |
New Member
Join Date: Dec 2021
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I'm a: Knowledge Seeker
Posts: 3
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![]() I know this thread is almost a year old but I have some questions related to this power supply.
I'd like to replace this PCH018 with an ATX power supply and I'm confused with this green (seemingly) PS_ON wire. There seems to be a little bit conflicting info in this thread. Is it a PS_ON signal or is it a PG signal? As I measured the PSU on it's own (not connected to the MB) I also found (as Dannyx has) the green line has has 3.3 V on it. Also 12 V is on the yellow lines all the time, by the way. This is without the fan spinning so I'm assuming the PSU is "off". Before I try something stupid (like short the wrong things) I just wanted to ask how this PSU/PC turns on. Is it just pulling PS_ON to GND? So if I would put in an ATX PSU I'd only have to make an adapter that connects 12V and PS_ON between the motherboard and the new ATX PSU? |
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