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TiN's Dungeon The mad engineer's home at KPC.

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Old 03-15-2014, 11:35 AM
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Talking Zombie power - level 2, or how to kill your hardware.

Long time no post...

One of overclockers wondered about usage of EPOWER and 290X VGA.
I usually don't touch ATI videocards, as I had not so enjoyable experience with X800 and 2900XT series before,
mainly due to drivers, but this time my EPOWER was under attack.
And I like to play with hardware, so let's give it a go, and see what can happen.

This overclocker is well known to all of you, and he sent me his hardware, with
marks "DON'T WORK" to see what I can do with that garbage

So this is a short intro, which can be labelled "HOW TO KILL HARDWARE" or "DO NOT MODIFY YOUR HW LIKE THIS".

Let's see what we got here..

Usually when deal with used hardware, no matter if it's overclocked gear or some ebay purshuase,
good rule of thumb is to perform inspection and revert all altered hardware to original state.
This can reveal damages and issues , so we can find out a way how to deal/fix borked stuff.

EVGA EPOWER CLASSIFIED
ATI 290X without heatsink (power inductors were in place originally, and board was covered with nasty red rubber paint)

He wanted to mix both together, to do some LN2 overclocking. But something did not worked up, so both pieces of hardware
were broken.

STEP A. Let's start with EVGA EPOWER power module.



First close look reveals lots of missing components.



0402 Resistors between power inductors were missing in some locations.
Also 2.2K NTC for thermal compensation near phase 1 inductor was missing too.
I really wonder what it needed to do, to remove those parts, as soldering iron will
not even fit into those areas!

Even more surprise - how one may expected EPOWER to work with missing parts?



Resistors between phase chokes are 12K7 1% 0402, they are used for current
sensing per phase, and without them phase OCP function will not work, causing
whole power rail to shutdown immediately! Near 0402 capacitor is 0.1uF X7R.

I had to remove all inductors with soldering bath on bottom, to get access to
those parts.



Also quickly discovered LOTS of soldering particles and specs around solid
capacitors. Those are NOT good, and can easily cause shorts, or drop somewhere
on working PC and cause more destruction.

This is why there are no warranty on EPOWER cards, as even well experienced overclockers
can abuse poor hardware like this. This is not product fault, by any means

So I masked bottom area from solder with high-temperature mylar tape:



And heated up 500W soldering bath. It's good easy tool to remove parts
from heavy-copper PCBs , like EPOWER's 8 layer one.
Solder bath was set to +300C level, to minimize thermal stress to capacitors hearby.



Even then I was wearing 3M protective eyeglasses, as solid caps may pop like a rocket if overheated.
My both eyes are still important to me, so little more precaution is always a good thing.

1 minute later....



Now can use usual 45W soldering iron to put back missing components and clean up PCB
from solder specs.



Then use same soldering bath to put inductors back again. After that - bigger 100W soldering iron,
with lots of flux to clean up any solder around pads and pins, and remove excessive solder from board.

Don't be in rush, check everything first before powering things on. Clean up assembled board with alcohol.
Check resistance on all power rails (+12V, +3.3V, output), all fine, not shorted.
Visual inspection under microsope - all seem good, no shorts or borked parts visible.

Now connect +12V input power from my trusty EVGA NEX 1500W, hook probes to input and output

And....



No problems with EPOWER now, we can use it, even after such abuse from overclocker fella.

STEP B. Borked 290X



Okay, everything seem not that bad on this videocard...
But if we take cloooser look:

First sign that card was benched under LN2/subzero:



Oxidation on pads, nasty salt and crystals formed due to exposure of ice/water



So next time you think about RMA'ing your borked hardware - think twice if it worth it
Simple 150mm macro lens reveals this stuff very easily.

Chipped off capacitor on back side near GPU:



Poor pad is detached from PCB substrate...



Solid capacitors were desoldered and replaced to bottom side. This is okay, when
it is done properly with powerful soldering irons. But it was not the case in this
example:



You can clearly see that soldering iron had issues with power transfer to capacitor
pads or was simply had not enough power. I usually use 100-150W soldering iron and
heating PCB first to do such soldering. Remember, solder will not melt till all
PCB copper is heated to proper temperature (which is about +250-260C).

You can see correct temperature visually, by having solder easy flowing on pads.
If it sticks, not melting - DO NOT apply mechanical force or push pads. It would not
help soldering, but only damage PCB/components:



Just like what happen here. Person who was trying remove inductor was
in hurry, or had not heated copper well enough, and applied mechanical force
to lift inductor. Result - pad is destroyed, copper plane now have huge void.
To fix this PCB - now need to shhrrr-shrrr rest of copper plane VERY WELL,
and solder another copper foil or plane right next to it, filling void with metal.



Same on another location. You also can see poorly done job for shhhr-shhrrr soldering
mask (protective pain on PCB surface).



Exposing soldering mask is required to provide good area for current flow.
It must be as big as possible, and uniform to do job well. Otherwise soldered
wires or planes to such small area areas will cause cracks and PCB damages with
any mechanical force applied. So more area helps not only with electrical,
but also making everything much more reliable.

Now not so easy visible damages:



Poor 0402 capacitor near PWM IC had peel off on pad. Multilayer ceramic capators are
VERY EASY to short by cracks or pad damages. So without any question - this one
getting replaced with new one.

This damage was done because too thick wire was soldered to cap, and with little
stress to that wire (for example when cleaning board or removing nasty red paint)
will damage soldering joint.



Same goes to 0402 resistor. Resistive element (black thing on resistor) missing
any contact or pad from right side. Pad was left on PCB when wire was pulled off.
Not good, but luckily still was able to measure resistor itself with a probe and get it replaced too.



Also nasty butchery around PWM IC pads. It's hard to see, but cut around pin 4
is actually too deep, piercing thru second PCB layer! When you cutting your traces,
don't apply much force, as there are many layers under surface, which you not want to cut or short!

Also some solder specs here and there were needed removal.

To be continued.....
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Old 03-15-2014, 11:35 AM
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TBD.
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Old 03-15-2014, 11:35 AM
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TBD 2
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Old 03-15-2014, 11:36 AM
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TBD 3
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Old 03-15-2014, 11:36 AM
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Final TBD
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Old 03-15-2014, 12:34 PM
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Hahahha .... Very very bad shrrr shrrr on that poor board , butcher is the apropiate word in English TiN eventhought our first language is not English , well word it. Got my popcorn ready
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Old 03-15-2014, 01:34 PM
rbuass rbuass is offline
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amazing job
you are not only the # 1 but also a great photografer
nice pics...great job...great allllll
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Old 03-16-2014, 09:13 AM
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Epic!
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Old 03-16-2014, 10:42 AM
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Part 1 really is a guide on how not to solder :/

Someone should have practiced on a less expensive part first :/
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Old 03-16-2014, 09:45 PM
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On expensive stuff you learn quicker!
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