SupraDrive 500XP and termination

[Dr Laser]

Dear ALL

Got myself this unit but ran into a problem. Scsi Termination. First I connected my SCSI zip drive. I had no device detection. Good thing that Zip drive has onboard termination. I put a jumper and device detected. Now Amiga boots from it no problem. Then I decided to put 2.1G Segate Hawk....nothing. NO SCSI detected. (I have v6 Rom.) Checked the manual for segate. Tried different jumpers...nothing. It looks like SupraDrive only see properly terminated drives and it looks like that segate doesn't have onboard termination. So what the best thing to do. There are a sockets for resistor network between external and internal SCSI plug. Will it help. If so what is schematics for resistor network. Is there other way to terminate my drive. BTW Seagate Hawk ST32155N 2.1GB and it was tested on PC.

Thanks.
A500

[mechy]

If the zip is external and the seagate is internal,both drives need to be terminated,and the controller should not be. remember the rule is each end of the scsi bus needs termination and nothing in between.the controller would be terminated if you only had internal or external devices,but not both.

saeagate hawk info is here: http://www.seagate.com/ww/v/index.jsp?vgnextoid=fb1a5a802efbd010VgnVCM100000dd04090aRCRD&vgnextchannel=f424072516d8c010VgnVCM100000dd04090aRCRD&locale=en-US&reqPage=Legacy

You need to set the hawk to a different device number than the zip,and then jumper term enabe,enable motor start,and term power from drive-no other jumpers on drive.

that should get you up and running. If it still does not work,you may have to supply the bus with term power by jumpering the drive accordingly but the supra should be doing this already. pin26 of the 50 pin ribbon should show +5v.. be careful
 if checking not to short to other pins!

Mech

[Dr Laser]

They are both internal. Sorry for not making it clear. When I connect my internal ZIP drive. ID set to 1 and terminated. then it works fine. Take out termination jumper....no detection.
Disconnect ZIP drive. Plug Hawk ID set to 1 term enabled/term power from drive.....nothing. No detection. I'll try enable motor start and see if it makes a difference.

[Zac67]

A SCSI bus must always be terminated on both ends. With internal devices only, the Supra Drive and the last drive on the cable require termination.

If you don't have / can't find the resistors packs for the Supra you can alternatively use an external 25-pin terminator (Apple style, an active one is a good choice).

A badly terminated bus may not run at all or may cease to run at any time.

If both devices are internal and you have no means of terminating the controller but there's no problem with the other two, you can plug the controller in the middle of your SCSI cable and put the devices on its ends, terminating it properly. It'll work but don't think about using the external SCSI connector like this - that would illegally branch off a third end of the bus which will never work.

[psxphill]

A SCSI bus must always be terminated on both ends. With internal devices only, the Supra Drive and the last drive on the cable require termination.

Yeah, you're terminating the cable not the drive.
 
Usually you enable the termination on the last internal drive and plug a terminator in to the external port if you don't have any external devices, otherwise you plug the terminator into the last device.

[Dr Laser]

Connected enable motor start. Drive doesn't spin now. Decided to test with an old SCSI I temporary pulled from my MAC classic II. Everything works. Pulled out terminator network off the back of Mac SCSI drive. No detection. I need to terminate because looks like Hawk doesn't have onboard terminators. What should I do? Get 2 connector internal cable and put a terminator on one end? Terminate external connector? Use 500XP internal socket for terminator network.