1541 problem: Not finding files, Killed a VIA on VIC-20?

[DistantStar001]

So I just got an old Commodore 1541 (VIC-20 colors, longboard) from my local friendly e-recycler. I can't say that I'm shocked that it has issues (it's missing more than half its screws), but I wasn't expecting it to damage my VIC-20.

At first, it seemed to respond correctly. The red light lit up on power on, then turned off. So I connected it to one of my VIC-20s and the drive reset on power-up of the computer. However, when I tried to retrieve the catalog (LOAD"$",8) it hung up and on repeated attempts eventually gave me a "FILE NOT FOUND" error. Then things got weird. The drive began hanging up and giving a flashing light error, and then the cursor disappeared from my screen. I unplugged the drive from the VIC-20 and got a black screen! I then tried it on a second VIC-20 and got the same bad behavior, but my cursor was fine.

At first, I thought the black screen issue was the VIC chip but decided to test that with a different 1541 to see if the computer was executing code. However, when I powered it back on, the screen was back, but with no cursor. I tried disconnecting the drive and got a black screen again. At this point, I was pretty sure it was one of the VIAs, so I removed the first VIA from the board and got a normal boot screen minus the cursor. I took a spare VIA from another VIC-20 board, and now the computer is back to normal?

Needless to say, I'm a little hesitant to hook this drive up to another computer as I only have one spare VIA left. Likewise, I don't want to try this on any of my C64s as I don't have any spare CIAs. Still, I'd like to get it going if I can. If nothing else, it looks so much better with my VIC-20s and the newer C64-style ones. Any suggestions as to what happened? and what I can do to diagnose and fix this without risking damage to any of my other equipment?

[DistantStar001]

Ok. So I've done some more testing and the drive seems to work (somewhat).  I reseated and swapped the VIAs and got it to work with my other VIC-20.  However, when attached to the first VIC, the drive will spin and the red light stays on even though there is no power to the computer (even when the VIC is not plugged in), but when I turned it on, the drive resets and acts as normal.  I was even able to load a catalog.  

However, loading programs is another story.  Also, the drive gives a flashing light error when I inserted a 16k RAM cart into the VIC, but it was still able to retrieve a catalog but errored out when trying to load an 8k game (Moons of Jupiter).  I did replace both VIAs on the first VIC-20 and verified that the disk and game loaded perfectly with a different 1541 drive.  

I then tried the same steps with the second VIC-20.  The drive reset as normal with the 16k cart but still failed to load the game.  After a bit, there seems to be a read error with the drive and the head resets to track 0 (1?).  Then I tried loading a game that didn't need the 16k cart (Cosmic Combat) and it loaded fine.  So I'm guessing that drive has an issue loading after a certain point?  Large files vs small files?  

I'm guessing my next step is swapping the board with one of my other drives to see if the malfunction follows the board or the drive mechanism.  Still, I'm curious why the same drive would behave so differently with two different VIC-20s?  Both are early two-prong boards.  the second is a year older and has a PET-style keyboard, but I'm not sure why that should be a problem?  I've never had a problem with either of these computers, the RAM expander, or the floppy disk (new old stock) before???  I've used each of these with three other 1541 drives before with no issues.  So if anyone can clue me into what's going on, I'd be very grateful.

[DrVeryEvil]

The last time I saw that a drive was running all the time, the problem was the rectifier in the 1541. Also make sure the head slides easily on its rail. Sometimes a drop of lightweight machine oil gets it moving.