SCSI TERMPWR

[Cloudschatze]

I'm not sure if this is the right venue for this sort of question, but hey, who knows...

I am currently on my third SCSI CD-RW drive, in just the last six months. The first experienced a failure in the head mechanism, and the second... I'm not entirely sure. Third time's a charm, right?

Not wanting to purchase another drive anyime soon, I'm investigating any possible issues that might be contributing to their premature demise.

The logical SCSI chain looks like this:

Code:

XV-5080(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)---VSR-880(6)
Int.TERM                                         Int.TERM

My one area of concern is with "TERMPWR," the (approx.) +5V used to power the SCSI-bus terminators. Depending on which conflicting information you happen to stumble upon, it should either be supplied by just one device, or by every device in the chain. From what I gather, unless the SCSI chain is significantly lengthy, having a single provider seems to be the best practice.

As fate would have it, every single device in my chain supplies ~1A TERMPWR. But, is that a problem?

Most SCSI-2+ devices have a diode to protect against reverse current, but suppose the diode in the CD-RW was of an incorrect rating; what type of failure might result?

In any event, the current drive is a later model than the prior two (PX-W124TSI), so one can only hope that, for this reason alone, it might be more reliable...

[the_doctor]

i havent used SCSI in years, but i thought the first and last devices needed to be terminated, but that's it.

[Cloudschatze]

The XV-5080 and VSR-880 are internally terminated, so no problems there.

Realistically, the drives were probably just on their way out to begin with. I have no idea how much prior use either saw, since they were purchased second-hand.

[Patrick Chang]

I'm not sure if this is the right venue for this sort of question, but hey, who knows...

I am currently on my third SCSI CD-RW drive, in just the last six months. The first experienced a failure in the head mechanism, and the second... I'm not entirely sure. Third time's a charm, right?

Not wanting to purchase another drive anyime soon, I'm investigating any possible issues that might be contributing to their premature demise.

The logical SCSI chain looks like this:

Code:

XV-5080(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)---VSR-880(6)
Int.TERM                                         Int.TERM

My one area of concern is with "TERMPWR," the (approx.) +5V used to power the SCSI-bus terminators. Depending on which conflicting information you happen to stumble upon, it should either be supplied by just one device, or by every device in the chain. From what I gather, unless the SCSI chain is significantly lengthy, having a single provider seems to be the best practice.

As fate would have it, every single device in my chain supplies ~1A TERMPWR. But, is that a problem?

Most SCSI-2+ devices have a diode to protect against reverse current, but suppose the diode in the CD-RW was of an incorrect rating; what type of failure might result?

In any event, the current drive is a later model than the prior two (PX-W124TSI), so one can only hope that, for this reason alone, it might be more reliable...

Hi Cloud,

From the way you connect your SCSI chain... it makes me think of something like this:

AHA-2940(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)---AHA-1542(6)
Int.TERM                                                                       Int.TERM

Of course the AHA-2940 and AHA-1542 are on 2 seperate PC in this example.

May be you should consider connecting the chain the following ways:

XV-5080(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)
Int.TERM                                             Int.TERM

or

VSR-880(6)---PX-W1210TSI(3)---PCD-47B(0,1,2)
Int.TERM                                              Int.TERM

Hope this helps.

PC

[Cloudschatze]

Hi Cloud,

From the way you connect your SCSI chain... it makes me think of something like this:

AHA-2940(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)---AHA-1542(6)
Int.TERM                                                                       Int.TERM

Of course the AHA-2940 and AHA-1542 are on 2 seperate PC in this example.

May be you should consider connecting the chain the following ways:

XV-5080(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)
Int.TERM                                             Int.TERM

or

VSR-880(6)---PX-W1210TSI(3)---PCD-47B(0,1,2)
Int.TERM                                              Int.TERM

Hope this helps.

PC

Hi Patrick,

I've not had any issues since replacing the CD drive this last time, so I think I'm set.

Also, I hadn't noticed this before, but the "code" diagram for my SCSI chain isn't displaying correctly. Instead of showing the termination at both ends of the chain (like it does in Notepad), it's being incorrectly displayed with termination in the middle. I'm not that ignorant, honest.

So, the chain looks like this:

XV-5080(ID:7, Int.TERM)---PX-W1210TSI(ID:3)---PCD-47B(ID:0,1,2)---VSR-880(ID:6, Int.TERM)

[Patrick Chang]

Hi Cloud,

From the way you connect your SCSI chain... it makes me think of something like this:

AHA-2940(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)---AHA-1542(6)
Int.TERM                                                                       Int.TERM

Of course the AHA-2940 and AHA-1542 are on 2 seperate PC in this example.

May be you should consider connecting the chain the following ways:

XV-5080(7)---PX-W1210TSI(3)---PCD-47B(0,1,2)
Int.TERM                                             Int.TERM

or

VSR-880(6)---PX-W1210TSI(3)---PCD-47B(0,1,2)
Int.TERM                                              Int.TERM

Hope this helps.

PC

Hi Patrick,

I've not had any issues since replacing the CD drive this last time, so I think I'm set.

Also, I hadn't noticed this before, but the "code" diagram for my SCSI chain isn't displaying correctly. Instead of showing the termination at both ends of the chain (like it does in Notepad), it's being incorrectly displayed with termination in the middle. I'm not that ignorant, honest.

So, the chain looks like this:

XV-5080(ID:7, Int.TERM)---PX-W1210TSI(ID:3)---PCD-47B(ID:0,1,2)---VSR-880(ID:6, Int.TERM)

Hi Cloud,

Is that your physical chain? Sharing 2 SCSI devices between 2 MIDI devices with SCSI port built in?

PC

[Cloudschatze]

Hi Patrick,

I've not had any issues since replacing the CD drive this last time, so I think I'm set.

Also, I hadn't noticed this before, but the "code" diagram for my SCSI chain isn't displaying correctly. Instead of showing the termination at both ends of the chain (like it does in Notepad), it's being incorrectly displayed with termination in the middle. I'm not that ignorant, honest.

So, the chain looks like this:

XV-5080(ID:7, Int.TERM)---PX-W1210TSI(ID:3)---PCD-47B(ID:0,1,2)---VSR-880(ID:6, Int.TERM)

Hi Cloud,

Is that your physical chain? Sharing 2 SCSI devices between 2 MIDI devices with SCSI port built in?

PC

Yes, precisely. Since neither device is accessed simultaneously by both the XV-5080 and VSR-880 (nor exists the need), I've yet to run into any problems that might be associated with having multiple initiators.

Well, come to think of it, the VSR-880 may technically only be a "temporary initiator" besides.

[Patrick Chang]

In that case should be fine. As long as no simultaneous access to either one of the SCSI devices from both the XV-5080 & VSR-880.