scsi problem

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i'm having problems connecting a cd-rw and a dvd drive to my onboard scsi card. it is a dual channel ultra160 device and i'm using 68pin to 50(?)pin adapters to plug into the drives. i was having problems with termination but i believe that that problem is solved, as the error message has disappeared. however on boot up when the scsi card shows up it won't scan through the devices. i can enter scsi control panel and configure the device but it also hangs when i try to do the other option (scan devices or whatever)...

any suggestions...
 

Yahiko81

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Jul 17, 2001
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I don't know much about scsi, but try changing the id number.

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G

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sorry probably should have included this in my first post but have tried changing the id number of both drives. oddly enough this is what cured my termination problem.
 

Yahiko81

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Jul 17, 2001
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Hmmm, I'd check and make sure that you have it terminated correctly. either the cable has to have termination or the last device on the cable needs to be terminated, I believe. I really don't know that much about it.

Nice <b><font color=green>Lizards</b></font color=green> <b>crunch</b> Trolls cookies....... :smile: Yummy!! :smile:
 
G

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there is a lvd terminator at the end of the cable and the last device on the chain is terminated. i've also tried without the lvd terminator and with the lvd terminator and without the last device being terminated. i get an no termination error when the last device is not terminated and also when the id's are not set properly, but otherwise no error it just doesn't scan through or detect the devices it just hangs. i've also tried disabling wide negotiation in the scsi boot utilities, but it has no effect.

thanks for your responses i appreciate all the help i can get.
 

Yahiko81

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Just use the lvd terminator at the end of the cable and don't terminate the devices. Then try changing the id's again you may have moved one of the id's to the one that the controller is using. If that doesn't work we're going to have to get someone in here who knows what he's talking about.

Nice <b><font color=green>Lizards</b></font color=green> <b>crunch</b> Trolls cookies....... :smile: Yummy!! :smile:
 

Yahiko81

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Sorry, I'm out of ideas for now. I'll keep checkin for you though.

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G

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All of my SCSI drives have a jumper on them to enable, and disable the built in chain termination circuitry. Remember to enable termination on the drive physically on the end of the SCSI chain, and disable it on all others. Probably your SCSI card auto terminates but you might want to check that out too, since both ends of the chain need the termination.

Another potentially useful tidbit which helped me was, knowing to make the drive you want as C on SCSI ID 0 if possible. other HD's can go on higher SCSI ID's. I don't really know if it is required but I have good luck using 5, and 6 for my CD drives.
 
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i have no scsi hard drives and i believe my cd-rw to be scsi id 5 and my dvd to be 3 or 4 (have tried several combinations) and my controller is 7. i believe my card should self terminate, but haven't seen anything in the manual or in the scsi utilities that alows me to activate it if it is disabled.
 

Yahiko81

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I believe you said it was an onboard controller so those options may be in your bios.

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khha4113

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I think your problem lies on the controller is <b>Ultra3 Wide</b> when your devices are not. Its signaling is <b>16-bit wide</b> and your CDRW is only <b>8-bit</b>.
You can read more info about SCSI <A HREF="http://www.scsicablesource.com/LVD_FAQ.asp" target="_new"><b><font color=red>here</A></b></font color=red>

:smile: Good or Bad have no meaning at all, depends on what your point of view is.
 
G

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which brings up a good point... i can't get to my bios when the devices are connected. when i hit f2 it says "entering setup..." but it still hangs on the scsi display screen. i will try disconnecting the devices and looking in setup.


keep the ideas comin' though...
 

Kelledin

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One thing to remember...NEVER, EVER double terminate your bus. It leads to very strange problems like this one. You should have one terminator on each end of the bus and no terminators between those two. Typically the SCSI controller works as the terminator for one end of the bus, and your cable has a built-in terminator on the other end.

Kelledin

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Kelledin

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Typically, though, the controller should auto-negotiate on boot. Adaptec controllers are normally very good about this auto-negotiation...also, I believe all Adaptec controllers have a hardware termination setting (a jumper or a resistor pack), even if the setting isn't documented. I've seen that setting correct strange problems like this on AHA2940 (AIC7xxx) UW and U2W controllers.

As for the signaling, as long as you're using a 16-bit cable with both high and low bytes LVD-terminated on each end (and nothing double-terminated) you should be fine. The bus should just automatically drop to single-ended mode if there are any single-ended devices connected.

Also, to whoever started the thread (the back button is dangerous in the middle of posting :wink: )...how long is your SCSI cable? Generally I'd worry if the thing's over 1.5 meters total (although I believe Ultra SCSI can theoretically reach up to 3 meters). Also, make sure there's at least 9 inches between each connector on the cable and no more than 6 inches between the last device on the bus and the cable's built-in terminator.

A word on TERMPWR jumpers, in case you didn't know this already: this is a bit confusing the first time you see it. "TERM POWER" settings don't control whether a device terminates the bus. Rather, if enabled, it tells a SCSI device to provide additional power on the SCSI TERMPWR line (part of the SCSI cable) so a terminator can do its job better. Enabling it may help if you have four or more SCSI devices.

Also, putting sharp creases in SCSI cable is BAD (this actually goes for any ribbon cable, but single-ended SCSI and ATA66/100 are particularly sensitive). I typically make folds in ribbon cable by rolling the fold point around a pencil or the like.

It's possible that adding the converter+device+cable is exceeding the maximum allowable "stub length" of the SCSI bus. "Stub length" refers to the length of the traces branching off from the SCSI cable to a SCSI device. I believe maximum stub length is 4 inches on Ultra/UltraWide SCSI--and the device's PCB trace lengths between connector and logic chip are included in that limit. 68-to-50-pin converters (especially cheap, cheesy ones) can add enough stub length to confuse any device that's already close to the limits.

How does the bus respond with only one device connected? Does it behave a bit better?

Kelledin

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thanks for all the suggestions. apparently my devices didn't like the lvd cable. i found an old 68pin ultra scsi cable and things worked themselves out... now i've got other problems but will start a new thread...
 

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