1581icide

[istvan]

Anyone ever had a frayed extension cord for years, and every time you looked at it you thought, "Hey, I should really do something about that,"?  Take my advice, folks, you should really do something about that.  Otherwise one night you'll hear a popping sound and learn that none of the stuff plugged into that cord works, and then you'll discover it's because the wires have touched and one of them melted away.  You may also end up with a dead 1581.  As the extension cord was plugged in to the same surge protector as the Commodore stuff, the short was downstream from whatever protection might have been offered.

The 128, 1571, and 1581 were all powered up at the time (I just leave everything on 24/7 because my VDC gets REALLY cranky when it's cold).  The 128 and '71 are running just fine, but when I turn on the '81, both LEDs turn on and the stepper motor hums.  With the drive on, it'll hold the heads right where they are, and the buzzing gets louder if I try to move the heads manually.  Switch the drive off, slide the heads to a different position, switch the drive back on, and it'll hold them there - no attempt to reposition or seek for the directory track.  I'd call this behavior rigor mortis, but I don't think that's a proper electronics term.

Tried a different power supply, no luck.  None of the chips or components get hot to the touch if the drive is left on for a few minutes.  The stepper motor is controlled directly by the 1770, so at first I was thinking the problem must be between there and the mech.  But, the C128 will just hang on startup if the '81 is on, no timeouts or anything, and there's no LED flashes to indicate a problem during the self-test.  The drive also fails to respond if it's started with the mech unplugged, so I'm wondering if the 6502 in there is even getting off the ground and managing to run any code at all.

Any ideas about the next step for troubleshooting?

[Stephane Richard]

This is hard to evaluate...basically, at this stage, i'd see how easy it would be to get a replacement chip and replace it if it's not too voodooish to accomplish.

in a typical scenario, the circuitry around it probably flexible enough to throw in a toaster element in there and make yourself some toast while using the damn thing lol.