M-Audio Profire 2626
This is a very rewarding repair I did for our rehearsal room/recording studio. Since we're doing a lot more rehearsing than recording our recording equipment just stands around and collects dust most of the time.
The main recording gear is a venerable M-Audio Profire 2626 and the last time we decided to fire it up we had an unpleasant surprise. The audio inputs and outputs worked perfectly but the interface would not get recognised by any desktop or laptop we had available.
First thoughts were that we had a faulty cable, but our backup cables didn't work either, so there was something wrong with the interface.
As it turns out, there is a pretty common issue with the Firewire connectors (especially the 6 pin variant) called Late Vg. This happens when the data and power lines get engaged before the ground connection is made. The electrical discharge is high enough to fry the Firewire controller. Old and therefore loose connectors are especially susceptible to a Late Vg event. TI has some pretty detailed explanations here [pdf].
With that in mind I opened the interface and located the Firewire controller. The Profire 2626 has a TSB41AB2 TI Firewire controller. I decided on also changing the Firewire ports since they were the root cause of our mishap.
The whole operation went pretty slow since I've never soldered a HTQFP package. This particular package has a .5mm pin spacing, way below anyting I've ever soldered before. To make matters worse, I managed to lift a pad durring the desoldering process. While this usually means the board is unusable, I was extremely lucky! The same signal (GND probably) was available on one of the neighbouring pins, so I macgyvered a solder blob between the two pins.
The good news is that all my tinkering paid off, the board got instantly recognised by a computer. We do have some more tests to run, but for now everything seems to be back to normal...