Tuesday, March 29, 2011

Upcoming Commodore Meetings...

Just a quick post to let everyone in the PNW know that there will be some important dates to mark on your calendars for upcoming Commodore meetings. Starting April 17th we will be kicking off Commodore meetings in Sumner, Washington! For those of you who are in the Seattle/Tacoma area and have been looking for other Commodore Users/Enthusiasts to hang out with, this is it. The meetings start at 5:20pm and run until 11:00pm every third Sunday of the month at the Pierce County Library 1116 Fryar Ave Sumner, WA 98390. Scheduled thus far April 17th, May 15th, and June 19th. Feel free to send suggestions or ideas of contest and/or projects you would like to see at the meetings. More details, and the calendar can be found here http://tech.groups.yahoo.com/group/UPCHUG_Amiga_C64/ We are gonna have some fun. Would love to have guest speakers come and chat, and new ideas introduced. We will be following an agenda similar to the Portland Commodore Users Group http://pdxcug.org :

  • Introductions
  • Announcements
  • Presentations
  • Show and Tell
  • Q&A
  • Group Project
  • Tinker time
  • Discussion
  • Gaming time

Hope to see you all!

Wednesday, March 9, 2011

MSD SD-1 and MSD SD-2 Super Disk Drive Repair

I thought adding a section on the repair of the MSD SD-1 and MSD SD-2 Super Drive would be helpful to all out there that have the common problem of an old MSD drive that just quit working. One of the most common problems with the MSD drives is the capacitors. The capacitors installed on the drive motor circuit boards leak electrolyte. After years of the electrolyte leaking the corrosion begins to eat away at the traces on the circuit board, and cause damage to nearby circuit board components.  
     As you can see in this picture, the leaking capacitor has spewed electrolyte all over the surrounding area causing traces to be eaten as pointed out with the arrow. The ICs near the capacitors also need to be removed and checked for underlying corrosion caused by the leaking capacitors. In the following pictures you see where the IC SN7406N has been removed to further clear any damage done cause by electrolyte. You will need some Isopropyl Alcohol, a toothbrush, solder, soldering iron, desoldering braid, and a small flat head srewdriver (to scrape) for the job.  
     First, open the drive up and carefully remove the drive board from the drive mechanism. There are 3 screws holding the board down, and 4 circuit plug-ins. Be careful not to yank the plug-ins. Once the board is removed you will see that there 5 capacitors. 2 on the right, 1 on top, and 2 on the left. The capacitors you will need are 16v 10μF, and 16v 47μF. Be careful not to order caps that are too tall, as they will rub against the adjacent drive when re-installed.  You can order supplies from http://www.jameco.com  The pictures on the left show the sequence of repair on the leaking capacitors. The 3rd-5th picture on the left show the eaten traces repaired, the IC removed, and the capacitors replaced. 
      Carefully desolder the capactitors, and IC that need to be replaced. Use desoldering braid, on the back of the circuit board, and a hot soldering iron to remove the solder. *Note: mark down the polarity of the capacitor before removing, so that when replaced they are in the correct position, and any plated holes covered over by corrosion should be poked through with a tiny wire. Rock the now loose capacitors back and fourth until the capacitors are removed. Once they have been removed, use a toothbrush with alcohol to clean the surrounding area. Once thoroughly brushed down, use a small flathead screwdriver or razor to scrape the area down to the copper traces. Be careful not to remove the trace itself. If for any reason the trace has been removed, you can use solder or quick grid repair compound to mend the trace. 
     As you can see on my board on the right, I scraped a good deal of corrosion down to the copper on my board. It is important to know where everything is before scraping, so that when you are replacing the capacitors and ICs that they are replaced in the proper position.  Replace the capacitors and IC, and resolder them into their correct position using a hot soldering iron and rosin core solder. 
     Carefully reinstall the board back on the drive mechanism upon repair. *Note: ensure all cables are reattached before turning the drive back on.  Below is the drive mechanism circuit board schematic for reference:

        The leaking capacitors are the most common problem with the MSD super drives. You will notice when you turn your drive on that it may blink 7 times. This is an indication that their is a problem with your drive mechanism. Here is a list of errors noted by the LED on the MSD panel when applying power to the drive:

 Number of Flashes         Component
                             1               Microprocessor U7
                             2                    RAM Ul
                             3                    RkM U2
                             4                    RAM U3
                             5                    ROM U5
                             6                    ROM U6
                             7               Drive Mechanism

The MSD Super Drive user manual is loacted here: http://staff.washington.edu/rrcc/uwweb/MSD%20SD-2/MSD.TXT

Diagrams and scehmatics for
the MSD SD-1 and SD-2 main board are on Ray Carlsen's schematics website:

Complete downloads for MSD SD-2 here

     A big thanks to Ray Carlsen and his work for helping the Commodore community continue to lead the way in the 21st century!

Commodore SX-64 Executive Portable Computer