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  Another CBM D9090 by Bill Degnan - 11/30/2009 09:50
I have a second CBM D9090 ROM A, to test, and see if I can get it up and running. It's totally stock, other than the fact that the cover is missing. My other D9090 is a ROM C I think.


  CBM D9090 Update - Tandon 603s by Bill Degnan - 12/05/2009 05:43
Notes on D9090 S/N 2074 diagnosis and attempted repair.

To start I "re-seated" the 6532's on the top controller because the drive was reporting a one blink error code (see codes here).

That was not the only problem. As with the first D9090, the original Tandon 603s is bad. This time, the drive was experiencing "stiction" which is a term used to describe when a read head sticks to the platter and as a result often prevents the drive from spinning.

I "de-stictioned" it by first taking the drive enclosure apart, and then removing the hard drive (Tandon 603s). I used a torx screwdriver to remove the metal plate of the 603s revealing the platters. I carefully spun the drive from the center, being careful not to touch the platter or read head. I put the 603s back together and applied power to the drive. The stiction condition was removed, the drive now spins.

In the process of re-installing the bottom controller card I noticed that a jumper fell off (one of the posts broke off), so I soldered a piece of wire to each post, to reconnect the jumper connection permanently.

I screwed everything was back in place and fired up the enclosure. Now I get the "all clear" blink code. I waited ten minutes to let the drive stabilize.

?ds$ returned the 73 / OK code.

I attempted to header the drive. The computer reported "bad disk"

I have no replacement 603s, so I may have to repeat what I did with the first D9090 and turn it into a D9060 by using an ST225 and snipping the jumper (More..).

  Tandon 603s Replaced by ST241 by Bill Degnan - 08/17/2017 23:57

Ethan D writes:
"..It's _usually_ the drive mech that's bad if a format fails. Those are
old drives. They are also uncommon models. Fortunately, one can sub
a Seagate ST225 in a D9060 or a Seagate ST241 in a D9090 and they work
(at the original 5MB or 7.5MB capacities at 4/6 heads and 153 tracks -
the extra tracks are ignored - it's probably possible to bump the
number of tracks up to 254 by altering the ROM code, but I don't
recall if anyone has done that). ..

oh, I did not know you could use an ST241 too, I converted my D9090 to a "D9060" by using an ST225, but I'd rather get the larger capacity if I can. I'll have to try that some time.



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