--- On Fri, 12/16/11, 33black <[email protected]> wrote: > Tried using a SCSI cable from the G3 > I have, which I know works, and > nothing. Still doesn't recognize drives. > > Any other thoughts?
SCSI ID on the internal drive should be set to 0. Take all three Id jumpers off. Termination on the internal drive should be On or Enabled. Termination power (TERMPWR) on the internal drive should be set to be from the bus or self powered. Do not set it to supply TERMPWR *to* the bus. (Only the Mac Plus needs one drive set to that.) You *can* set *one* device to provide TERMPWR to the SCSI bus but it's not required, though it may help with an active terminator at the end of the external SCSI chain. Except for the Plus, the Macintosh built in SCSI controllers are auto-terminating when only the internal OR external connections are used. (The Plus SCSI has no internal connection.) What may be the problem is your Classic's auto termination may have failed or it could be the SCSI controller has failed. Have you tried connecting a passive terminator plug to the external SCSI port? If you've verified the correct ID and termination for the single internal drive, and it still won't work with an external terminator or an external device with correct ID and termination, then I'd say you need to find another mainboard - unless there's some little fuse or other discrete component that's blown up and can be replaced. No consumer model Macintosh's built in SCSI sends "Start Unit Command" (the old servers that don't run Mac OS do), so drives must be jumpered to auto start or delay start. Delay start waits for the number of seconds matching the SCSI ID after power-on before spinning up. That's intended to reduce the power load, which is higher to start a drive than to keep it spinning. SCSI ID 0 will spin up immediately, ID's 1 through 6 will wait 1 to 6 seconds. (7 is always the ID of a Mac's built in controller.) Delay start is usually not needed on a Mac because models with room for more than one internal drive have power supplies with enough "grunt" to spin up all drives at once, and externals have their own power supplies. Many old SCSI drives, possibly including the Classic's original 40 meg, had removable terminating resistor packs instead of permanently installed resistors and jumpers. To disable termination on those, the resistors had to be removed, tossed somewhere to save them, where they'd get lost forever... Some of those drives, especially the thinner models, had resistor pack sockets laying down flat. Without the resistors plugged in the sockets themselves look like resistor packs in a square molded case. The terminating resistor packs I've seen were all "conformal coated", in other words lumpy, not neatly block shaped. -- ----- You received this message because you are a member of the Vintage Macs group. The list FAQ is at http://lowendmac.com/lists/vintagemacs.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To leave this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/vintage-macs Support for older Macs: http://lowendmac.com/services/
