View source for Recapping Indigo2 power supply

[[Category: Indigo2]]

'''NOTE:  This page is a copy of one written by Tony Mantler, and was obtained from [[http://www.sgidepot.co.uk/i2psu.html]].'''

<p style="border: 5px solid ; background-color: red; color: white;"><strong>The
inside of your powersupply contains lethal voltages which remain deadly
long after the unit is disconnected from all external power sources. Do
not open your powersupply unless you are experienced with repairing
high voltage electronics or have a very strong urge to kill yourself.
If you do not take appropriate precautions, such as using appropriate
methods to discharge capacitors, YOU WILL DIE.</strong></p>

<h1>Reconditioning a failed Indigo2 powersupply</h1>

<h2>Electrolytic Fundamentals</h2>

<p>Every electronic component eventually dies, but the expected
lifetime for electrolytic capacitors is quite a bit shorter than most
parts you'll find in the average computer. Unfortunatley, these
capacitors play a vital role in the functioning of the powersupply of
your computer.</p>

<p>Electrolytic capacitors rely on the surface area created between an
etched metal electrode and a liquid electrolyte (which forms the other
electrode) to function. Unfortunatley, this liquid electrolyte has a
nasty habit of evaporating over time, which can range anywhere from 25+
years for a very large/cool capacitor to 5 or fewer years for a
small/hot cap.</p>

<h2>The Indigo2 R10k/IMPACT powersupply</h2>
<p><small>May also apply to other Indigo2 powersupplies</small></p>

<p>A common failure mode for this powersupply is for it to randomly
switch off the system while in use, often on cool days. The system will
fail to respond to any external stimuli except for disconnecting it
from the wall for a short period. Alternatley, the system may fail to
power up at all, only showing a small twitch on the fans when plugged
in, or when the power switch is depressed for the first time after
plugging in. This failure mode is most likely due to dead capacitors in
the powersupply.</p>

<p>The Indigo2 powersupply is divided into two sections, HV and LV. The
HV section contains the main transformer, the HV filter, and the
switching circutry. This is where most of the fun happens. The LV side
contains the LV filters and supporting logic for controlling and
monitoring the powersupply's broader functions.</p>

<p>The HV side is the side of interest for us. It will contain 4 small
capacitors that should be replaced, C119 (100Âµf 25v), C??? (47Âµf 35v),
C122 (1Âµf 50v) and C91 (10Âµf 35v). (If you want to cheap out, replacing
only C122 and C91 may be enough)</p>

<p><a href="http://www.sgidepot.co.uk/i2ps_componentside-a.jpg">Click for bigger view<br> <img alt="Indigo2 Powersupply HV board component
side" src="i2psu_files/i2ps_componentside-p.jpg" height="240" width="320"></a></p>

<h2>Actual repair process</h2>

<p>Basically, this is a pretty straightforward component swap. I
purchased the replacement capacitors for a whopping grand total of
$4.50cdn (be sure to specify 105Â°c temperature rated capacitors).</p>

<p>Once you've got the powersupply into a somewhat exploded state (note
that it's not possible to disconnect the HV board from the LV board -
the large conductors leading from the main transformer are soldered in
place) and removed the plate from the bottom of the HV board, just
desolder the old components, solder in the new ones, clip the leads,
reassemble, say a few prayers, grab the fire extinguisher and turn it
on.</p>

<p>Don't forget to make a note of which way the capacitors are oriented
before soldering them in place. If you get it backwards, you can expect
things to explode in a most spectacular way. (The negative side is
indicated on the capacitor with a white stripe, and there will be a '+'
silkscreened on the board to indicate the proper polarity.)</p>

<p><a href="http://www.sgidepot.co.uk/i2ps_solderside-a.jpg">Click for bigger view<br> <img alt="Indigo2 Powersupply HV board solder
side" src="i2psu_files/i2ps_solderside-p.jpg" height="240" width="320"></a></p>

<h2>Success</h2>
<p>... is most definitley not guaranteed. <tt>:)</tt></p>