Cougar CMX 700W no power

[lezsimply]

Guys need help on this power supply. I usually don't repair power supplies but this one is a request from a friend. Its not that expensive although this might be challenge.

Its a Cougar CMX 700 watts power supply model: CGR B2-700. The owner told me he used desktop for about 3 hours then it suddenly turned off and he saw smoke came out at the back of the computer case. Unit has no power.

At first glance there are no burnt mark or crack components, I needed to remove board from the case to see further and I noticed the plastic underneath the board have marks on it obviously a burned component.

On the image I attached, 3 components are partially burned, 2 resistors and a ceramic capacitor.

Does this kind of power supply have diagrams or something? I also took code from the board. Hope someone might have schematic for it. If I were to replace those component is there a chance it will burn again? Thanks!

[mariushm]

Re: Cougar CMX 700W no power

That chip in the fourth picture is an offline switcher, it produces 5v standby. If there's no 5v, the motherboard won't start.

Test D81, D82, D83 (the diodes by the switcher), if one is shorted or broken, replace all three.
Replace resistors ..1002 is 10000 or 10kohm, the other I can't read. The capacitor.. no clue... probably 100nF 35-50v based on the chip datasheet (here: , see page 8 or page 11 figure 15, look at traces on mb and compare with example in pdf but keep in mind that example is for 12v, your psu configures it for 5v so some resistor values will be different).

You can find that TNY277pn on eBay.. probably cheaper than shipping it from Mouser: http://no.mouser.com/ProductDetail/P...nOjhSBaqhriw==

[lezsimply]

Re: Cougar CMX 700W no power

Thanks mariushm! I already ordered the chip TNY279PN and will soon arrive.

Tested diode D81 and found faulty, D82 and D83 are below 400 so I would still replace them also.

I'm still doing some research as to what value is c82 and r79 but you might be right on the capacitor value. Do you also know what value is r84 and r85 with label 2204?

If huge filter capacitor is faulty will it cause TNY to burn up? Thanks again!

[mariushm]

Re: Cougar CMX 700W no power

Be sure to replace the diodes with diodes of similar technical parameters. The diodes should have a code on them. Google it. If there's no code on them, follow the traces and compare with the datasheet and the instructions in the datasheet to see what kind of diodes are recommended.

2204... the last digit is the number of zeros after the other numbers so it's 220 0000 or 2 220 000 or 2.2 megaohm

The large capacitor very rarely fails.

You should check other parts around this IC before replacing it with a new one, other parts may be faulty. Check as much as you can.

[999999999]

Re: Cougar CMX 700W no power

A large % of the time the primary fault in a case like this is shorting out of the primary switching transistor(s).

Do c82 and r79 really need replaced? It's hard to tell from your pictures but it looks like they merely had some solder disrupted by the diode overheating.

[chipmaster]

Re: Cougar CMX 700W no power

Hi lezsimply. Did you already fix your PSU?
I have the same problem here. Mine shuts down all of sudden. Since my PSU is already out of warranty, I tried to check it myself and hopefully I can be able to repair it. I found a burnt R79 chip resistor which is already "open" upon checking it using my multimeter. Based on the value, although burnt, it is still somehow readable, it says 2R20 which means 220 ohms. Had it replaced with a ceramic-type resistor with same value but it also got burnt. There is still another problem. I am suspecting the +5VSB chip, the TNY279. Resistor R79 goes directly to pin4 of this IC. And that's where I stopped. I don't think this IC is available here in Manila.

[japlytic]

Re: Cougar CMX 700W no power

I found a burnt R79 chip resistor which is already "open" upon checking it using my multimeter. Based on the value, although burnt, it is still somehow readable, it says 2R20 which means 220 ohms. Had it replaced with a ceramic-type resistor with same value but it also got burnt.

2R20 stands for 2.20 ohms.

[chipmaster]

Re: Cougar CMX 700W no power

2R20 stands for 2.20 ohms.

Thanks friend. You're right, it's 2.2ohms. My mistake, anyway, it got burnt also. I am really suspecting the IC here. Any other ideas would be helpful. Thanks again.

[lezsimply]

Re: Cougar CMX 700W no power

I havent fix the power supply. Don't have reference for the parts that got burned. can you post pictures of yours? btwt

[Stefan Payne]

Re: Cougar CMX 700W no power

Have to take a look on my salvaged one.

But IMO it's not that good PSU because Su'scon Secondarys, not that great Voltage Regulation and high Ripple according to my chroma report...

[lezsimply]

Re: Cougar CMX 700W no power

yeah. this got a lot of negative reviews thats why a new revision was released. It has black pcb board for the new one.

[CapLeaker]

Re: Cougar CMX 700W no power

as for C82 the smd cap on the back side of the board... measure with your ohm meter to see if it has a short. If it doesn't test shorted, touch up the solder and leave it alone.
R79 looks like a 2.2 Ohms resistor and that looks like it is blown to me. I also would test the component before and after this resistor.
R78 should be a 10k Ohm resistor. See what you get if you are measuring in circuit. If it doesn't read near 10k ohms, you have to measure it out of circuit.