Next FCUG meeting - Sunday, November 21

[RobertB]

Happy Thanksgiving, C= and Ami aficionados!
     The Fresno Commodore User Group has its next meeting from 11 a.m. to 1+ p.m., Sunday, November 21, at

          The Pizza Pit Restaurant
          2705 N. Blackstone Ave. (corner of Blackstone and Princeton)
          Fresno, California

     This month we'll look at photos and video from the October 22-24 Amiwest Show.  There will be a demonstration of music synthesizer program, PetSynth, with a Commodore PET 4032 computer and MSD-SD1 disk drive with JiffyDOS (well, JiffyDOS is not really necessary with the PET).  Also we'll try to tie up any presentations not finished in September.  I hope Murphy's Law doesn't strike. 

          Bringing the massive PET 4040 drive
          was out-of-the-question,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug

[RobertB]

There will be a demonstration of music synthesizer program, PetSynth, with a Commodore PET 4032 computer and MSD-SD1 disk drive with JiffyDOS (well, JiffyDOS is not really necessary with the PET).  Also we'll try to tie up any presentations not finished in September.  I hope Murphy's Law doesn't strike. 

Yes, Murphy struck!  Now Ray Carlsen is going to try to repair the MSD SD-1 drive.  The drive is not recognizing any disk insertion and has its disk activity light always on (though there is no motor activity).

          Dropped it off at his place on Thanksgiving Day,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org

[RobertB]

Now Ray Carlsen is going to try to repair the MSD SD-1 drive.

Ray is the miracle worker!  Once again he has performed the impossible (or nearly impossible) and has repaired my MSD SD-1 drive.  Here is what he said about his repairs --

"I finally had a chance to get into that drive and I was able to repair it... sort of. Turns out the mechanism is bad. Someone had been into it (connector backwards, resistor clipped out) and, not knowing what they did and not having any schematics for the drive electronics, I decided to try an old PC 360K mechanism... and it works great! I guess it just ignores the unused top head. It just needed a few jumper changes and we're good to go."

(snip)

"The JiffyDOS works too. Apparently it was necessary for CMD to re-code both DOS chips to install JD in that drive, but only one has the DOS switch wired to it. Anyway, I wondered why CMD used a 27256 EPROM instead of a 27128 since half of it is empty. I suppose they had a lot of those bigger chips in stock or they were cheaper at the time. They probably bought in bulk since they used that same EPROM for their C128 Jiffy modules."

(snip)

"FYI: It seems there are two versions of the original DOS for the SD series drives... 1.5 in the SD-1 and 2.3 in the dual SD-2. They are apparently interchangeable but I have not tested them in all configurations. I suspect the JiffyDOS chips will work in both single and dual drives. I'll have to test that sometime. I don't think users would buy JiffyDOS for the SD-2 since most would want the dual drive for copying disks, and that's what the Lawrence Hiler "Mass Duplicator" fast copy chipset was for."

(snip)

          Thank you, Ray!
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org

[RobertB]

    Master C= repair technician, Ray Carlsen, gave me some further insights on the MSD drive and its TEC mechanism, he said,

"...I found the problem with my TEC mechanism, the one that suddenly failed to write in my SD-2. The caps all checked reasonable with an ESR checker but some of them were physically leaking, and some nearby board traces were eaten away by the electrolyte. I had to scrape away the paint over the top of the traces to see them, but sure enough, that was it. I cleaned and repaired the board, changed the caps and fired it up... success! Even though the other mechanism was working, I did the same thing to it so there shouldn't be any more trouble with those mechanisms. I noticed the motor board in both drives was clean, no corrosion, and the caps there all checked good, so I left them alone. Those are easier to change anyway and don't really damage anything even if they do leak."
      "Most other MSD drives I've seen have much more damage from leaking caps than my drive had. If the cap crud migrates under an IC, that chip has to be removed to get to the damage. Restoring those drives is possible but not much fun (read: expensive) if anyone asks. It's best to get to them before they puke..."

          Truly,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org

[RobertB]

...I decided to try an old PC 360K mechanism... and it works great!

Here's some more detail on how Ray repaired my MSD SD-1 drive and about how more finicky MSD SD-2 drives are,

     "...at the recent prompting of a fellow tech, I decided to try all the old drives in my stash. Out of eight, three worked, two without any changes except to move the DS (drive select) jumper from D1 to D0. Those two are a Panasonic (Matsushita) JU-455-5AAB and a an unnamed drive with a sticker that said "made for IBM", Model YD580. The latter is installed in your SD-1 with new holes drilled for the replacement drive mounting. The third drive is a Toshiba FDD6379R3J, and besides the DS jumper, I had to jumper PJ18 which was called "FSTP" to enable that drive to work. These tests were all done in an SD-1 but when those same drives were tried in my SD-2, they didn't work for some reason. Sharing a bus with the other drive??? That dual drive is very touchy in this regard and the original drive mechanism [TEC-501 mechanism] seems to be the only thing that works in it."

          Truly,
          Robert Bernardo
          Fresno Commodore User Group
          http://videocam.net.au/fcug
          The Other Group of Amigoids
          http://www.calweb.com/~rabel1/
          Southern California Commodore & Amiga Network
          http://www.sccaners.org