Scott:
I just read through all the postings with regards to your Tyros USB troubles. Frankly, I am going through a similar experience.
To answer your question, the original HDD I installed which worked for about a month was a 40 GB made by Fujitsu. When the T2 stopped recognizing it, I replaced it with a new but identical HDD making sure that it works before I installed it. When the T2 failed to recognize the second HDD I again replaced it with a 60 GB Toshiba unit. All these HDD are on the Yamaha recommended list.
The tech at the repair shop inspected and re-soldered the connections of the HDD harness and the 60 GB Toshiba HDD was recognized for only a couple of duty cycles. The repair shop tech then called for Yamaha support and received many conflicting suggestions. They finally said that there are many problems with the Fujitsu and Toshiba HDDs and suggested that I replace them with an IBM Travelstar (or 40GB) HDD.
At this point the repair shop wanted to return the Tyros to me. I told them that this is un-acceptable and that I'll call Yamaha myself.
I got on the phone and talked to Harvey Casey at Yamaha. He called me back a little later and told me that he will send the repair shop a new mother board next week. I am hoping that the problem will be fixed as the main reason I bought the T2 is because of its recording ability.
In the meantime, I am using my PR 3000 but I miss the T2's recording capabilities.
Joel
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Joel