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ITTSB Blog Specific > ITTSB - Small projects by Kiriakos & User reviews
July 2020 PSU CORSAIR CX750 Repair - CP9020015 - CWT PUQ-G - Quality Monster
Kiriakos GR:
New gift in my hands ... an damaged CORSAIR CX750 CP9020015 :)
This seems as Quality Monster ;)
Inner capacitors are Panasonic at the important parts of the circuit and also Capxon at lesser of importance circuits.
The exception in this PSU this is the addition of DC to DC converter which control voltage stability.
Such circuit will not aloud voltage sag under load by the offering of instant output correction.
These are new technological additions of 2012, but these smart additions they also contribute in to a greater complexity and degree of difficulty, when this thing it must be repaired.
Within one hour of diagnosis I did found the problem and also the reason which caused it.
Here are some pictures from it for now.
Kiriakos GR:
Gentlemen I found the smoking gun 8)
A faulty CPU connector over a motherboard, this caused sparks and arching, this is an occasion very RARE in which the power supply electronic protection circuit cannot handle or resolve.
This electrical incident forced several APEC 9990GH N-CH 60V 100A( its one ) MOSFET's them to collapse.
These are mounted over a PCB this called as SYNC-Card.
Molex the manufacturer of such plugs, informs us that its female pin this can handle 9A Max.
I did order the necessary spare parts, now I am assuming after a month of waiting (Speed-Pack CN) that I will see this little monster having a second life :)
In the past 48 hours I did inspect by my LCR meter all the capacitors, all are at 100% of health and specifications.
Additionally for confirmation purposes I did visit the website of Capxon, the capacitors series in use this has 5000 Hours specification.
The replacement series of the 2200uF 16V Capxon this can be the Panasonic KZE.
One small problem if these capacitors require replacements, this is the diameter of 10mm, all newer revisions they are now manufactured at 12.5 mm.
The installation of three 12.5 mm electrolytic capacitor ( one next to another) this is possible but not an easy job.
Either way I am now convinced that the specific PSU, this has not operate more than a few months.
Kiriakos GR:
Few words about this PSU electronics design history, education combined with entertainment. :)
CWT manufacturer this build several PSU for other brands.
The specific PCB and circuit named as CWT PUQ-G this is printed at the PCB of LEPA G850-MAS PSU , this is identical to CORSAIR CX750 - CP9020015
https://www.techpowerup.com/review/lepa-g850-mas/4.html
Even so, the CORSAIR CX750 - CP9020015 this has an additional heatsink over the hart of the system that is two powerful Mosfet over the lengthier heatsink on this PCB.
Now it is obvious that CORSAIR - CP9020015 this is a down-rated 850W PSU with optimal cooling than the overrated LEPA at 850W with lesser heatsink surface.
Therefore the CORSAIR - CP9020015 this is a better build in the details, but it is rated at just 750W, in order this to provide an extended life cycle, because any wise person he will not stress it more than that.
Now while LEPA G850-MAS this is identical PCB , they did use Panasonic capacitors at 12V Rails, they did that so to improve mostly the impression created at the eyes of product reviewers. ;D
Panasonic KZE this is also a 5000 hours capacitor, as is the Capxon, but the Panasonic has Lower ESR, which this might help just a bit at very high Loads at 850W.
Now the LEPA G850-MAS seems to were stressed up to 1150W until circuit protection engages.
Here is another tip, CORSAIR did not aloud at CWT them to stamp this PCB as CWT PUQ-G because CORSAIR wanted this detail to stay hidden.
Today it looks as funny, but even the newer Corsair Gaming Series GS800 this is based at the identical PCB too. :)
It is obvious that a few first Revisions of CX750 were not that perfect, until the CWT PUQ-G get in to make the job, but the fame of this model (CX750) were injured due the product reviews.
And now Corsair returned back by the good PCB by using a new naming as Corsair Gaming Series GS800 among with an DC fan with LED lights.
https://hexus.net/tech/reviews/psu/42425-corsair-gaming-series-gs800/
In both reviews the Identical PSU design shown worthy and a great performer!
The new name of GS800 .. July 2012 .. this now restored the true named capacity of the circuit it self at 800 Watt continues when the Max headroom stops at 1150W.
Most Gamers PC, this will never use over 350W continues, but this is another bed time story. :)
Kiriakos GR:
All right !! Today I did put back together all the parts and wires which I did remove under the electronics fault diagnosis stage.
Back at desoldering stage one electrolytic 470uF 16V this came out damaged, also at the specific PCB it was planed to be three of them, so now I though as good idea to add and the third.
But now I have to handle an small new issue, the ones that I have in stock they are a little bit taller, now I am planning a small modification which will solve this minor issue too. :)
Kiriakos GR:
This is a reference relative to DC Fan speed control
The DC fan this is 140 x 140mm.
Over the Sync Card at 12V output there is a Thermistor TTC103 ( this has operating temperature minus 30C and up to 115 Celsius )
According to Junction Temperature characteristics of the AP9990GH MOSFET it temperature it should retained at 50C up to 100C for long lasting operation.
AP9990GH MOSFET this can handle Max temperature of 180 Celsius
And therefore the Thermistor TTC103 this will set the DC Fan at Full speed when the Corsair Sync card PCB this is at 115 Celsius ;)
In other words ... the DC Fan speed control this is triggered according the 12V Rail load.
Now in the scenario in which the DC Fan cannot cool-down the Sync PCB at lower than 115C I am assuming that over temperature protection circuit will kick-in and the PSU will be forced to shutdown.
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