About to add external CD rom.

RedDaemonFox

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i have sourced a Mitsumi SCSI cd rom and have it ready to run. The main issue is : it doesn't say anything about adding termination to it, all the included software is for DOS. Do I need to change the termination settings? I have one SCSI HDD inside my 3000D currently and I know NOTHING about termination, I know about RIMM termination, but thats it. Also, the manual mentions Parallel port, is there a way to tell if my device is parallel or not?
 

Kin Hell

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Terminate both ends of the SCSI bus (cable) & un-terminate the devices.
You might get away with terminating the Cable with the Hard Drive & the CDROM. It depends how good/bad your hardware is. ;)

Kin
 

AndyLandy

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My advice for anything SCSI-related, which has served me well over the years is:

Fiddle with it until it works. Sometimes you need to terminate the bus, sometimes you don't. Occasionally you may even need to explicitly not terminate it. So long as you change things whilst the devices are all off, you should be fine, incorrect termination won't break anything.

SCSI is dark magics, As such, I also recommend sacrificing chickens, that sometimes helps. :)

Good luck, and have fun!
 

Kin Hell

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I forgot ot say:

If your SCSI card has terminator packs installed, you will have to remove them when using more than one device. They normally push into sockets & run paralell with the 50 Way IDC header on the controller. Sometimes 2 long ones or more usually, 3 shorter ones. ;)

Kin
 

Merlin

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@ DC270Mhz

Also make sure than the logical Unit Number ID for each unit and the controller are set to different IDs. If two devices have the same LUN, then the system may not see them, or at worst, lock up.
 

rkauer

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I forgot ot say:

If your SCSI card has terminator packs installed, you will have to remove them when using more than one device. They normally push into sockets & run paralell with the 50 Way IDC header on the controller. Sometimes 2 long ones or more usually, 3 shorter ones. ;)

Kin

Charlie, my friend, the resistor packs (or termination jumper on modernish SCSI controllers) must be sacked out only in three cases:

1- You have internal and external SCSI devices (so the controller is in the middle of the chain. In this case both last devices (last internal & last external) must have termination set on.

2- You used a single cable but the controller is in the middle of the cable, with devices hooked on both ends of cable. Again, termination must be applied only in the last devices.

3- You have two active or passive terminators (don't mix active with passives!) hooked on both ends of the cable. Then ALL devices, controller included, must have the termination disabled.

Third option is the best set-up when you have active terminators.
___________________

Most SCSI CD drives have a jumper for enabling/disabling termination, check on the case's label or google for the model you have.

___________________
 

Kin Hell

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@ rkauer

Not when using an Archive Viper Tape streamer.
A3K with Termination to the controller, & both ends of the SCSI bus, but before the Viper, thereby leaving the Tape Streamer un-terminated to function. ;)

Also, not many SCSI controllers have the ability to remove the Resistor Packs. Indeed, the CSMKIII has no termination onboard at all. The cable must be terminated @ both ends.

@ thread

SCSI does not always conform to the standards it is suppose to endorse. Either you know SCSI or you'll be fiddling around till you're blue in the face.

Kin
 

RedDaemonFox

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Got a new issue: I attached the CD rom. The HDD wouldn't spin up. So, i removed the CD drive. The HDD wouldn't spin up there either. So now I suspect that attaching it messed up the configuration. I even changed the device jumper on the HDD, and it wouldn't boot. The HDD is the only device on the chain, the end of the cable has a black covering on it I suspect is the terminator.
 

chiark

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Does this external drive have a switch/selector on it to set SCSI ID? Does it have a termination enable switch, or a passthrough connector to which a term block can be added?

It really is sounding like this isn't a SCSI disk. My guess is, worst case, it has grounded something that didn't want to be grounded (although good design should prevent that breaking anything) or -worse- put power where power didn't want to be. There's no power on the SCSI interface, and a parallel port device shouldn't send power on the parallel port, but you never know whether this is a proprietary interface...

Check fuses on the SCSI bus - if any. My guess would be you might need a new SCSI chip...

---------- Post added at 10:28 ---------- Previous post was at 10:22 ----------

Found my schematics for the 3000...

Pin 25 is connected via a diode (d800) to +5v - that could have gone.
Pins 8, 10, 11, 12, 21,22 and 23 are connectedt through pull up resistors in RP802 (220 or 330 ohm) to +5v
Each pin on the connector is connected through a ferrite bead (EMI1800-1817)

Naturally, most are connected to the WD chip too...

Have you left the machine on for 30 seconds or so to see if you get the normal kickstart "insert workbench" screen? If so, good, it's just scsi that's dead. If not... Hmmm... Start looking at +5v traces!
 

AndyLandy

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I have to confess that I've been very lucky with SCSI over the years. I plugged a CD-RW and 4GB hard disk on to my HC series II, with the card in the middle of the chain, and it all worked seamlessly first time.

I'd be surprised if the hard disk has been killed by another device on the SCSI chain. Certainly incorrect termination shouldn't do any damage. I guess it's possible that it's just bad luck that your disk has died. I have a couple of SCSI disks spare, but I doubt they'd survive shipping to the US.
 

chiark

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I think we can establish that a) it was a parallel drive (model number given on eab) and b) it's likely to have drawn too much on the +5V pin (pin 25) and taken out a PCB track and diode (d800) (castellan on amiga.org :D )

Should be an easy, if somewhat fiddly, fix.
 

Kin Hell

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SCSI is not something you can just fiddle with. You either know it or you don't & if you're not even knowing the difference between a Parallel device & a SCSI device, one should ask oneself, "should I be bothering?"


Kin
 

chiark

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I didn't see anyone saying, "hang on, nothing about termination, are you sure this is SCSI before you plug it in?"

Anyone can make an assumption / mistake which has unintended consequences. I still regret rushing when making config changes to a Single board computer, and applying 12v where only 5v should be: the magic smoke escaped, and it hangs in front of me as a reminder not to rush things or make assumptions :D

Luckily it seems that Castellan has seen this before and it's a simple fix.
 

AndyLandy

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SCSI is fine to fiddle about with, so long as you're using SCSI hardware. :) Incorrect termination or mismatched IDs won't do any damage. The only things you have bear in mind are don't hot-plug any SCSI devices and don't mix HVD and LVD. (Ideally, just avoid HVD SCSI like the plague)

@Dreamy, I hope you get it sorted, mate. That's a right pain.
 

RedDaemonFox

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I've ordered a multimeter, and I'll check d800. Over on EAB, they're thinking it blew the PSU. If, so I'm extremely lucky. There was no smoke escaping or sound, I'm thinking Chiark's right. I'm hoping I just blew the SCSI. I'm gonna diagnose some more today,
 

RedDaemonFox

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I ended up having to repair the track from pin 25 to the d800. I used 22-gauge wire and some rosin flux and 60/40 solder, and I am getting the diode very soon. Thank you Chiark and every else, I'm such a sausage at times
 

chiark

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Did you find any damage on the trace then? Pics, my man, we need pics! (zetr0 has his banning wand at the ready ;) )

Note that the real genius is Castellan... he's the chap that has seen this before: I was just guessing from the schematics...
 

RedDaemonFox

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The diode was intact, the trace was COMPLETELY burned up, plus the INT2 mod had come loose. i'll make up a thread in a few minutes with finished pics. I also fixed my 3640 card and washed my 2000's mainboard.
 
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