Johnny Billquist <bqt@Update.UU.SE> wrote:
> Please note the difference between "in the back" and "open up the back
> part". :-)
   I did note that difference, but on RA81 what you need to open is the
logic access cover, which is not the back part, it's more of the top part.
> Also, if you had bothered connecting a terminal, you ought to have found
> out that there is a help command... :-)
   I haven't done any trial and error experiments since I will soon have
the full docs.
> Not that I can remember if I've disassembled any RA82, since they are
> more reliable, but from my memory, the physical design is the same, so
> what do you mean it doesn't have a logic access cover on the top???
   The physical design of the part in question is not the same. The lower
deck is the same on both drives, and it contains the HDA, the read/write
board, and the spindle motor. The upper deck on both drives contains the
logic, but it's different between RA81 and RA82. On RA81 all logic is
accessed through the top of the drive with the upper deck lowered. There is
the logic access cover at the top, and when you open it, there are three
boards inside: the micrprocessor board, the personality board (where the
host interfaces connect), and the servo control board. The diagnostic
terminal connector is also there. None of this is accessible from the
inside when the upper deck is raised. On RA82, on the other hand, the logic
was re-designed. Apparently the microprocessor and personality boards were
combined into one. The logic access cover at the top no longer exists, and
the two boards are accessed from inside with the upper deck raised. The
bottom plate of the upper deck is on hinges and the servo control board is
attached to it. Swinging it open allows you to access the combined
microprocessor/personality board. But you don't have to do all this to get
to the diagnostic terminal connector, since it's accessible from the front
of the drive, right above the air filter.
   
   Sincerely,
   Michael Sokolov
   Phone: 440-449-0299
   ARPA Internet SMTP mail: mxs46@po.cwru.edu