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ATI X800XT Fan Upgrade for Mac G5
DC to DC Switching PSU (12Volts to +/- 18V & 48V)

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SC-1mk2 and SC-1mk500 Mic Preamp Kits



SC-1mk2 Preamp Kit  SC-1mk500 Lunchbox Preamp Kit 
 Tuesday, February 26, 2008
ATI X800XT Fan Upgrade for Mac G5
Wednesday, February 27, 2008 5:47:28 AM (Central Standard Time, UTC-06:00) ( )
So I bought this AT X800XT card... back when it was $499... the first one after a few short months, the fan got noisy and was dying... I sent it back to ATI, then ATI sent back a faulty unit (blocks appearing on the screen), so I had to resend it back again and then I'm good again for a few months.

This morning, my 2nd monitor (A Samsung) wouldn't come up. Just black. At first I thought my monitor died... bummer. That got me thinking... maybe I should get another 23" Cinema LCD :) The prices have fallen down to $799. (I got mine back at $1999).

Then just to be sure it's the monitor, I swapped things around... and lo and behold, my Samsung monitor was working!

I opened the G5 case, and see that the video card fan was totally dead... not spinning. NOT GOOD. I don't know how many days I've been running with this fan not spinning.

So today I pulled out the X800XT card and put back in my stock video card (fanless) just so I can continue working. It's a good thing to have spares.

I'm not going to bother sending this back to ATI again. I bought some replacement aftermarket fan and will try to fix this thing instead. Remove the junk ATI fan and use another one instead.

Will update this post as I go....

I just hope the 2nd video port isn't permanently damaged.

I just noticed today that due to the failed fan on my video card, it almost fried the components at the bottom of the PCB. Yes, it smell burnt. I was kinda disappointed when I saw this. I'm thinking maybe my video card is fried (literally).





 Remove the old crappy fan from my ATI card. This fan sucks. Do you hear that ATI?????




You can see the old thermal paste sticking on the cpu. So we'll need to clean that out.




And here's the clean chip. I just used an old cotton shirt, and an old toothbrush. Wiped it clean and made it shiny.

I'm using a Zalman VF700-Cu Quiet VGA Cooler fan. It's pretty cheap. $20 I think.

It also comes with some blue small heatsinks for the other chips (RAM?) on the card.

The connector of the Zalman fan isn't compatible with the headers on the video card.

So what do you have to do? Get a cutter, cut the wires on the new fan, cut the wires on the old fan and solder them together a'la Frankenstein. :)

I used some heatshrink tubing to insulate the connection. You can see it in the photo below, along with the new blue heatsinks.



Then... the moment of truth... Put it in my G5 and see if it still works. (Remember, the parts at the bottom of the PCB smells burnt and looks a little crispy.

And the result....... IT STILL WORKS! Now my second monitor works, and not shutting down (turning black). I've got good video on both monitors! :)

So that's done... total time, maybe 30 minutes.

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 Saturday, February 02, 2008
DC to DC Switching PSU (12Volts to +/- 18V & 48V)
Saturday, February 02, 2008 10:12:25 PM (Central Standard Time, UTC-06:00) ( )


Well, this DCC psu is giving me the headaches. One day, I thought I licked out the problem and it's as quiet as can be... next day, I turn it on, and the fyring noise is back again coming out of the speakers.

I've tested and used my oscilloscope to look for possible problems in the DC-to-DC converter, (though I did found some oscillations that I eventually fixed), there doesn't seem to be any improvement in the crackling sound coming out of my test preamp.

This PSU ripple has never been better, the "frying bacon" sound coming from the inductors is almost negligible, the waveform looks good... but still! There's that crackling sound coming out of the preamp.

In situations like this (i.e. when I become desperate)... I do weird things to my projects. I mean, what more can I lose?

And this time, I decided to remove jumper J1 on the SC-1 preamp, and run using AC coupling. That's strange... the crackling sound STOPPED!

So I went to my shelf, grab a new OPA134 chip, swapped out the old IC2 chip on the pre with the new one, and VOILA! The stupid crackling noise STOPPED! IT's as clean as can be... running on the DC-DC PSU.

I'm going to leave the DC-DC PSU running the whole day, and the preamp... and see if the noise comes back. Otherwise, I think a marginally defective IC2 on the SC-1 PCB was the cause of the noise problem, and not my DC-DC PSU.

I'm happy to report though that using an AC Adapter with my DC-DC PSU powering the preamp and the Mini-IO module, the AC Adapter doesn't even get WARM!


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