NeXT Computers

NeXT Computer, Inc. => Black Hardware => Topic started by: Rob Blessin Black Hole on July 01, 2019, 03:55:28 am

Title: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: Rob Blessin Black Hole on July 01, 2019, 03:55:28 am
Hello NeXT Community: So this is a new one usually the first culprit that causes a NeXT not to power up is bad power cord, battery or powersupply then DOA keyboard , keyboard connector , bad monitor cable , bad sound card where keyboard plugs in and lastly bad motherboard, Add Bad hard drive to the list thought I was going nuts but test on 3 different systems proved the drive caused it . The drive was actually working as was the slab then apparently something in the SCSI drive failed. So the NeXT must actually detect that there is a sever problem as in short with the drive??? Brian the drive to you as may be you can figure out what the heck is going on and hope it is not a future plague as this is a common Seagate 1GB drive. Fortunately we are moving everything over to SCSI 2 SD but my guess is a lot of you still have spinning SCSI disks so I Put this here for additional trouble shoot. Easiest way is unplug the drive from the motherboard, does the system power on ? If yes it is the drive.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: krazycat on July 04, 2019, 08:04:39 am
I had already noticed this problem on many of my slabs, it happens that when the electronic circuit of the disk drive fails, the slab does not start. Instead, when the hard disk has a mechanical problem, the slab can start and at the NeXT> prompt it usually shows the message "SCSI error".
When a slab does not start, my diagnostic scheme is usually this: check battery> check power cord> unplug SCSI disk> unplug RAM > check power supply.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: Andreas on July 04, 2019, 08:20:44 am
Quote from: krazycat on July 04, 2019, 08:04:39 amWhen a slab does not start, my diagnostic scheme is usually this: check battery> check power cord> unplug SCSI disk> unplug RAM > check power supply.

Will a slab start without equipped RAM like a cube? I have a color slab here with broken SIM holders wich doesn't start. I have exchanged the PS - nothing. On the same Soundbox/Cable constellation a proper slab will start.
If the slab works, i will glue the RAM.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: barcher174 on July 04, 2019, 10:13:21 am
What you're likely seeing is a board failure causing a short to ground on the logic board of the drive. The power supply should cut off in this scenario. As an FYI, I think these drives are of the vintage where it was still OK to swap the mechanism and the logic boards around. So you can do part swaps to get working drives.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: Andreas on July 04, 2019, 11:38:45 am
Quote from: barcher174 on July 04, 2019, 10:13:21 amWhat you're likely seeing is a board failure causing a short to ground on the logic board of the drive.

hm, i have not nstalled a harddrive now and the power button does nothing. Need the color slab only two RAMs of a pair or four? the first two RAM slots are not broken so i could test with 2x4MB.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: barcher174 on July 04, 2019, 12:15:21 pm
Sorry Andreas that answer was for Rob. You are talking about an original color and not the turbo right?  For the original I think it is 4 simms per bank. Can you hold them in place while powering up?  You should at least see the machine power up and the diagnostic LED blink when the banks are not fully populated. It sounds like you may have more issues.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: Andreas on July 05, 2019, 05:12:27 am
Quote from: barcher174 on July 04, 2019, 12:15:21 pmSorry Andreas that answer was for Rob. You are talking about an original color and not the turbo right?  For the original I think it is 4 simms per bank. Can you hold them in place while powering up?  You should at least see the machine power up and the diagnostic LED blink when the banks are not fully populated. It sounds like you may have more issues.

OK, looks like the logic board is broken. I have fixed 4 RAM sticks but nothing happens, no LED, no FAN spins on. I have tested a new PS already.
Title: Re: DOA Hard Drive caused slabs not to power up, It is a new issue
Post by: barcher174 on July 05, 2019, 08:00:30 am
The obvious thing to try is of course a new battery. I would then suspect the RTC.