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 

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. 
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. 

[Andrew-88]

Another recorded adventure of Kiriakos 

Therefore the incoming gift, this has reputable background as electronic design.
As soon this comes back  to life, what are your plans about it ?

[Kiriakos GR]

Another recorded adventure of Kiriakos 

Therefore the incoming gift, this has reputable background as electronic design.
As soon this comes back  to life, what are your plans about it ?

Hi mate!
Well as soon I will verify this PSU good functionality by my electronic DC load  https://www.ittsb.eu/forum/index.php?topic=1316.0 among with my oscilloscope https://www.ittsb.eu/GW-Instek-GDS-2102A-MSO-Review.html  then this will become a keeper PSU as spare for my main PC system.

Since beginning of 2009 I am using a HiPER HPU-4M780-PE   780W  this is a CWT  Taiwan  design, imported - distributed by a brand name Hiper-Group in UK.
Hiper brand were active and even honor any warranty plans for a few years, but they get out of the market by their own decision.

HPU-4M780-PE stats after eleven years in use.
After 10 Years + five months,  I had  to replace the 12V Rail electrolytic capacitor.
The YATE LOON DC Fan ( D14SH-12 ) this is running problem free all these years.

CORSAIR CX750-CP9020015 this is a more modern CWT design in comparison to HiPER 4M780 but equally powerful in Watts.
Actually both of these PSU,  they were priced above the 120 Euro mark, and as such their quality standards are high among with their reliability and longevity.   

[Kiriakos GR]

Few pictures from the CP9020015  DC fan this is also one  YATE LOON D14SH-12 
What now empowers my curiosity this is the secondary code 

At the year 2008~2009 this were L-SO1 and at 2016 this become L-SSS

Either way the CORSAIR CX750 Repair project this is now On-Hold  until spare parts arrival. 

[Kiriakos GR]

I wish to thanks AKASA in Taiwan and David Tai for the provided information of what is the AWG of  AKASA AK-CB8-8-EXT ATX 12V CPU extension cable !

Originally I though that in order of me to replace the damaged connector (ATX 12V CPU) both 4Pin plugs,  I would have to follow the expensive route of buying plastic housings, metal pins, special crimping tool.

But now there is a much better alternative !!     
AKASA AK-CB8-8EXT extension cable this is at reasonable pricing at below 5 euro and it has 18 AWG wires that is exactly of what this Corsair 750W PSU also using.

By getting one of them I can do a simpler wire to wire connection and use the new perfectly crimped connectors as 100% reliable spare-part. 

( I thought also taking the old 12V ATX CPU connector from a dead - old - low in wattage PSU,  but this is WRONG and Stupid plan to follow when you are repairing a high performance PSU ) .   

[Kiriakos GR]

Shopping from local market has the benefit of speed regarding delivery.
AK-CB8-8EXT arrival.
18 AWG this also confirmed.
Speaking of Molex plugs these are not from Molex brand,  the product seems assembled in China and at the 8 Pin plug there is ECI as brand logo.
I did a quick search about ECI ( brand or factory in China ) no results shown.

By having at hand my NEW dual ATX plugs replacement, I am now free to focus at the next step of this repair process.   
I am now waiting for Mosfet's arrival ... 

[Kiriakos GR]

The last piece of this puzzle arrived today.   

I feel that I have good chances for success, because I own Hot-Air rework and even a soldering station, both be at the above of average quality.

 

[Kiriakos GR]

 

Now I am working  on a few FRESH ideas about special electrical test and measurement harness for PSU voltage measurements.
And more tests under load will follow.