I assumed that the Commodore 1581 was failing because of a bad WD1772 IC (as documented in Part I). So I ordered a WD1772 replacement + the IC socket, I developed some basic desoldering skills, watched some desolderingvideos, and also got a cheap desoldering iron from Radio Shack:
So, I removed the board from the Commodore 1581 and started to desolder the IC. To my surprise the $11-buck desolder iron worked pretty well. I was able to remove all the solder from the the pins in a few minutes. The desolder iron just takes some time to reach the needed temperature, but besides that, it seems to be a great tool for occasional desoldering tasks (a hobbyist desoldering iron cost more than $250)
I got my 1581 like one year ago. It worked for 2 or 3 weeks and it stopped working. The stepper and the motor weren’t moving. So I guessed that the “floppy drive” was broken.
Quick introduction: the Commodore floppy disk drives have 2 major components:
The controller board: which has the 6502, RAM, ROM and other ICs to control the drive
The floppy disk drive: which is the “thing” that has the header, the stepper, the motor to spin the floppy disk, etc.
So, in my case, my quick guess was that the “floppy disk drive” was broken because the stepper and the motor were not moving.
So, I got different replacements:
Chinon FB-354 Rev. B: Was moving the stepper but making strange noises, so then I got a…
…a Panasonic JU-257: Was moving the motor, but not the stepper, so then I got a…
…a Chinon FB-354 Rev. E: Was not moving anything. Same symptoms as the original one.
When you purchase untested things from Ebay is hit-or-miss. Sometimes they work, sometimes they don’t. But what are the chances of getting 3 broken floppy disk drives?
So, this time I decided to read more about the 1581 and I found this info that says:
The original fault with a failing 1770 was directory corruption. Other
symptoms of a failing U4 include intermittent "file not found" and spindle
motor not spinning when the drive is accessed. One recent U4 failure showed
no stepper activity at power up (no "burp"), the green LED flashed once per
second repeatedly and the spindle ran continuously.
So my new guess is that I have 3 fully working floppy disk drives and one broken controller, in particular the WD-1770 IC which is responsible for controlling the floppy disk drive. The WD-1770 is soldered into the PCB, so desoldering skills are required… which I have zero. So time to learn how to desolder ICs. See you soon.