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SCSI HD doesn't boot internally in SE/30 (but works externally)

9166188

Well-known member
Got a HD (Maxtor MXT 540S) for my SE/30 but it won't boot as internal drive. Curiously, if I put it into an external SCSI case w/ active termination, it boots. So, the problem appears to do with termination. I managed to find some info (in german) about jumper settings. But its TP (TERMPWR) jumper (highlighted blue circle) on/off has no effect. Later, I realised this HD (taken from an IBM PowerPC) has 2 resistors Rt (highlighted in red) missing in my PCB.

Question: does it mean that there is no way I can use it as an internal drive for SE/30 or other 68K Mac in general?
 

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dochilli

Well-known member
I think, that Rt are the termination resistors. You need them, when you want to use the drive internal terminated.
 

timtiger

Well-known member
In my opinion the resistors are the green ones you have framed. They are called ‚resistor network‘. Anyway - the termination is often secured by a fuse.

Btw the info you have linked is czech, polish or so.
 

9166188

Well-known member

MrFahrenheit

Well-known member
I’d tend to the 220 Ohms based on general scsi specs. But maybe someone else here over has more experience?

In my opinion it’s more secure to use an internal Terminator: https://store.cwc-group.com/insc50maacte.html (or another terminated internal device)

I agree. Not sure if you are aware but there are terminator blocks that have both a male and a female end, so they can be inserted into the board without a cable, if necessary. Here’s a link to a ten lot but singles are available, too:

 

9166188

Well-known member
Before I proceeded to buying an internal terminator block as suggested, I thought I would give it another try.

I came up with a pretty good trick (I thought) by pulling out the PCB from the dead Apple HD that I was trying to replace. And plugged this PCB to the last connector of my 50-pin scsi cable to act as a terminator. Seems clever right? The anti-climax was that it did not work even though this Apple PCB has the right terminator resistors on it.

Before giving up, I switched the positions of my Maxtor HD and the Apple PCB on the cable. So, my Matrox is now the last in the ribbon chain while Apple's PCB is in the middle. And binge, it works magically defying my SCSI logic. I was really over joyed despite a little confused. In hindsight, the middle PCB "terminator" probably acts as a pass-thru in my configuration? Well, so much for SCSI alchemy today!

And thanks for everyone's support here!
 
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