A3000 - perplexed with problems

[Amiga4k]

Friend came down for visit with an A3000 in hand. Problematic booting, if any.  Unit has taken a surge/spike.

Floppy drive would spin, then stop. Manual spin of flywheel would re-start. Disassembled drive, used cleaner solvent to remove " TOBACCO FILM " from  flywheel and hub bearing.  Floppy drive now works.


Hard drives:  A2091 and motherboard both had boot drives attached. The A2091 was disabled (jumper) as needed to perform these tests.

NO BOOT, either drive:    replaced the 3.1 ROMS
The unit will  -now-  boot with an A2091 SCSI  card, but not from the motherboard SCSI controller.

The following chips were swapped out,  one at a time,, then the test was made again.
Buster11, DMAC 2,  SCSI  WD,  Paula.

Any ideas?

[adolescent]

If you boot from floppy, does HDToolBox see the drive?  You said it took a spike.  Has the power supply been changed?

[Castellen]

Could be a problem with Gary, as this device does a lot of misc system control functions.

Were the new parts you fitted definately in working condition?

It would also be worth checking if termination power is being supplied to the internal/external SCSI ports.  This comes from diode D800 (between the ext floppy and parallel port).  With SCSI devices connected to the motherboard controller, check for approx 5V on the cathode of D800 with the system running.  If there is no power (probably due to the diode being open circuit) then replace it with any common power diode such as a 1N4004.
Also make sure the boot device has a SCSI ID of 0, I've found this can sometimes help, as it's the first ID to be polled on power up.

Replace or check that the internal 50 way IDC ribbon cable is not dodgy.  The connectors can go intermittent when you least expect it.


If you need details of the SCSI controller, you can get schematics and the full service manual from my website:

http://amiga.serveftp.net


Anthony.