SGI Indigo 2 Impact PSU repair

Northsky

Reindeer Whisperer
Feb 8, 2019
23
28
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DISCLAIMER: Opening a power supply and performing repairs to it could be deadly! Do not attempt any repairs if you do not know what you are doing.

Hello all,

Thought I should write something about my most recent repair project here. Currently I have one almost dead Indigo2 Impact PSU (060-8002-001 Rev A) on-going repairs.

At the first round, I decided to try to follow a guide pointed out to me by Ian (http://www.sgidepot.co.uk/i2psu.html). I managed to successfully replace the mentioned capacitors on the High Voltage side of the supply, but that did not help. So now this week, I have started to finally investigate the Low Voltage side of the supply. This is probably the most difficult PSU I have attempted to repair so far. As Elf's great reverse engineering post indicates, the LV and HV sides are soldered into each other with thick slices of copper and it makes it difficult to work with.

So, for the Low Voltage side. I found one SOT-23 packaged component that looked suspicious when I did optical inspection of the LV board.
1579294152219.png

Also, on the opposite side of the board were some signs of dust and solder seemed to have blackened on a resistor. When cleaning that section with gas duster, the said resistor learned to fly, so to make space to put it back I replaced the closest capacitors to it. Also, as the contacts on the board and on the component were blackened, I used a scalpel to carefully scrape off the oxidized layer and applied some fresh solder on them. Here is a series of pictures of that process:
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To remove the capacitors, I used a soldering iron with chisel tip and 350 Celsius degrees set as temperature along with gel flux, leaded solder, and most importantly, a solder wick.
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To be continued on next post!
 
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1579296814814.png


Now that I got the resistor / capacitor issue solved I've started to investigate the suspicious SOT-23 component further. I have cleaned it and measured it as follows:
1579297176268.png


In diode measurement mode, 1 -> 2 yielded 0.603 V and the reverse was 1 V. Resistance was 5.567 kOhm. 2 <-> 3 was Open in both modes and directions. @Elf , your Indigo 2 Impact PSU is a bit different model, but this section seems identical. Could you please help a bit by measuring the component on your PSU so that we could compare results? If the results are the same, I can conclude that the part does not need replacement. However, if the measurements do not match, then this component needs to be identified so that a replacement could be ordered. :)
 
Edit: With apologies, I no longer wish to have involvement with SGUG or SGI communities in general,
and have also chosen to remove all of my content. Many things have changed since I co-founded, named, and ultimately
then left SGUG. There are many good people around, to whom I apologize for frustrating by removing these things, and
also many petty people that over the years whittled down both the enjoyment as well as sense of obligation I used to
feel to anyone else regarding what was ultimately just a hobby. Unfortunately one of the latter now writes the rules
and so it is time for me to take my things and go.

This message will replace all of my previous forum posts because deleting threads that I started would have removed
other peoples' posts.
 
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