June 13, 2021, 08:18:54 PM

Lifeless Super HD

Started by redruM69, April 29, 2021, 04:50:24 AM

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redruM69

April 29, 2021, 04:50:24 AM Last Edit: April 29, 2021, 04:55:41 AM by redruM69
New guy reporting in!  I recently acquired a Super HD that I'm attempting to get running.  I've owned and repaired boatloads of vintage machines, but this is the first X68000 I've laid eyes upon, let alone work on.

Overall really nice clean shape.  Dead PSU, which I learned is typical on these.  I've rebuilt the PSU with fresh Nichis and Panas, replaced a dead zener and 2 transistors also.  PSU now runs great with strong rail outputs.  The other boards in the machine look very clean.  No corrosion or signs of cap leakage.  I replaced the battery in the I/O board, and pulled and tested ESR on a handful of random larger caps from all boards.  Those were within spec.

Attempting to power on the machine.  PSU switch on, soft power off, power light is red, as I assume is expected.  Press the soft power, and it goes green.  Fan and HDD spin up, floppy drives will accept and eject disks, but the machine is otherwise lifeless with no video output or disk activity.  Pressing the soft power again will turn the power light a very dim green, but the rest of the machine remains powered up.

Yea yea yea, I know I should completely recap all the boards regardless, but for now my gut tells me something else is going on. 

Does anybody recognize these symptoms?  Any other suggestions before I shotgun every cap in this machine?


SuperDeadite

Sometimes the floppy ribbon cables go bad and only partially work.  These computers will refuse to fully boot if it doesn't detect both drives.

redruM69

Quote from: SuperDeadite on April 29, 2021, 09:42:22 AMSometimes the floppy ribbon cables go bad and only partially work.  These computers will refuse to fully boot if it doesn't detect both drives.

Interesting, I'll check the drives and cables.  Will this cause soft power to fail turning the machine off?

Fularu

Quote from: SuperDeadite on April 29, 2021, 09:42:22 AMSometimes the floppy ribbon cables go bad and only partially work.  These computers will refuse to fully boot if it doesn't detect both drives.
He should still have video out and the floppy icon/message showing up

At least my Ace and Compact behave that way, haven't checked with the 030

aje_fr

Plug the hdd cable.
On the super, if no scsi termination is detected, the computer will not boot.
Either scsi termination from hdd, either resistor network termination should be present.

redruM69

Quote from: aje_fr on April 30, 2021, 06:00:51 AMPlug the hdd cable.
On the super, if no scsi termination is detected, the computer will not boot.
Either scsi termination from hdd, either resistor network termination should be present.

Will this cause soft power to fail turning the machine off?  Will it cause no video?

redruM69

I got it to run!  Found a dead cap on the mainboard.  I still need to recap the I/O, but it lives!