• Hello, Guest! Welcome back, and be sure to check out this post for more info about the recent service interruption and migration.

Macintosh Portable 34 pin to 50 pin SCSI cable


Well-known member
just i just thought of a good idea??

What if i epoxy'd the IDC's together after I pop the wires on?? hummmmm

no doubt popping the wires on the 34 pin side would be easier!



No need, folks have been reworking ribbon cables on existing harnesses for as long as IDC has been around. I you're going into production, just buy new connectors and ribbon cable. Get the three part connectors with the double-back strain relief setup. I missed you request for a new graphic, I'll work on that, as well as a diagram for an assembly jig setup.

I've got some time, the major hacks are at the awaiting parts acquisition stage again. ::) I'll do a diagram before I do the 'ole Scrooge MacDuck dive into the 21" high pile of 1400s. Gotta prune that back to a reasonable height of unborken lids attached to tricked out books . . .

. . . and a pile of spare parts for distribution. }:)



Well-known member
For the time being, I'm pretty happy with this cable.

Got some bigger shrink tube at harbor freight This one I made today, turned out pretty decent.



last one for the night.


Last edited by a moderator:


THX, uni, it went a bit easier than I'd thought it might. This is the first time I've done the criss-cross on opposite layers.

I think it's a resistor to limit the Termination Power current, but it might be something else, gotta figure that out from the boards I've now got in hand.

p.s. can you click to get the full size image? It usually takes a while before I can view the full size.



Sounds right, I cleared my cache and now I can see it too. I figured as much, when I place attachments, I'll have to be careful about how I do it or clear my cache. I'm guessing that previews are a no-no.

If anyone spots a boo-boo, lemme know.

If someone wants to critique the layout, PLEASE do!

If someone knows how to add an LED activity circuit, that'd be very cool, I'll add it in.

If anyone knows the right component for the TERMPWR jumper circuit, I'll add that info into the diagram as well.

If someone wants to make a production file for Seeeding some boards, I'd be thrilled, I want a pair!

Like I said on the first page, this would make a great community project! :approve:

I especially like the notion of doing a mounting sled for laptop drives or a board that'll easily bolt up to a 2.5" SCA adapter. For the former, I've got an APS external 2.5" HDD case. For the latter there are several permutations to consider.

I can't imagine that the little SCA Drives we've been playing with and a tiny muffin fan could possibly use as much power as the big honking OEM drives. :?:



Well-known member
The 2.5" SCA drives draw too much power.

Some of the full size more modern hd's 800mb - 1gb consume less power then the 40mb Connor.

(As in my above post) the modern drives are quieter.

I just realized there might not be enough room in that area for a patch pcb,

so off the bat it would have to be kind of like the sca adaptors,

where the pcb pops right on to the hard drive and the 30 pin cable would make the whole stretch to the adaptor.

I suppost you could make 2 revisions, SCSI 2.5, SCSI 3.5,

Then one could just use a standard PC-Floppy cable to connect the PCB. :)

well they would have to hack of the end that flips pins for floppy 2.



Interesting, how far over budget are the SCA drives?

I've got the 50 pin connector flopped to the other side of the board on the layout. If I'm looking at the correctly, a 3.5" HDD will plug into the bottom of the adapter just like the SCA Drives do and the IDC34 cable will plonk onto their headers behind that in the same manner.

I've got the info for putting the 40 pin 2.5" SCSI drive socket opposite the 50 pin connector. I'll do that so the 2.5" drive will plug into the "other bottom" of the adapter exactly like the 2.5" SCA drives do.

Only one adapter PCB to adapt either type of drive, as necessary. ;)

Dunno if it'll work . . . I'll play with it in the AM . . . |)



Well-known member
well the original 40mb Connor hd is:

+12 - 250ma

+5 - 275ma

The IBM SCA Drive is

+12 - 800ma

+5 - 500ma

This newer scsi Quantum 700mb drive i have here is:

+12 - 210ma

+5 - 200ma

the 100mb scsi zip drive, witch works only because it does not use the 12v boost regulator just the +5v regulator

+5 - 800ma - but might still over heat the +5v regulator over time.

Yes to one PCB, -great idea Mr. Smarty pants. I have a 2.5 to 3.5 adaptor, but the power/data location config is non standard.

Screen shot 2013-05-28 at 2.59.22 AM.png



Very strange HDD mounting tray/setup in the Portable. Why the centerline mounting holes for the HDD? This is not convenient at all! :-/

I suppose you could make 2 revisions, SCSI 2.5, SCSI 3.5,
Then one could just use a standard PC-Floppy cable to connect the PCB.
. . . or just use the original cable! :eek:)

On a more serious note: you'd probably want to slit the lines on a PC FDD cable to match the original cable. Apple l could have folded the ribbon cable. It's not just easier to route the way it's done, it might help to keep crosstalk at bay to jumble the wires about like that on the way to the HDD since there don't appear to be enough lines for the alternate ground line method . . .



Well-known member
I dont think corss-talk is going to be a concern @ 1.5mb / sec, or across 5 inches of cable :p

Apple wasn't concerned with cross-talk with the original portable hd cable design, not sure why you would mention it now.

The 2.5 to 3.5" adaptor

I got it on ebay.



I mentioned crosstalk on the first page of the thread and now I'm wondering about it again. The original cable is slitted and done up in a double ponytail deal with wire ties making one full twist overall. That's likely way better than a straight ribbon cable in terms of crosstalk, so they might have been thinking in those terms. I'm trying to cover all angles so I'm thinking out loud here in .TXT . . .

. . . and kidding around in retaliation for that "Mr. Smarty pants" crack. ;)

Got linkage to that adapter?



I just figured out how to convert a Cheap@$$ 3.5"->2.5" IDE converter to a Luggable 2.5" SCSI cable! ;D

1) Desolder the edge mounted IDC headers for the 3.5" connection.

2) Solder the slitted PC FDD cable's stripped ends to the proper positions on the "edge card connector" where the headers were.

4) Mount it off the end of the SCSI HDD's headers so that the old 2.5" IDE P & G connection sockets hang in the air.

The cheap SCA->50pin 3.5" SCSI connectors can probably be converter as well.

1) Bake & shake all the components off the board.

2) Lop the ends, both MOLEX and jumper headers, off the PCB.

3) Install a straight soldertail IDC50 plug opposite where the male connector was.

2) Solder the slitted PC FDD cable's stripped ends into the proper thru-hole positions for the SCA connector.

I'll have to complete the diagram I did to figure out the SCSI Voodoo of the SCA adapters to give you the "pinout" for the FDD wires.

I'm not sure that this will work physically, but it appears that the board is narrow enough to fit below the roof. Someone else is going to have to test it.

If I damage the stickers, it'll void the warranty on my Luggable's perfectly serviceable Hard Disk 40SC. ;)



Well-known member
i just got this aztechmonster thing to work,

its pretty cool, quite fast, uses almost no power.

Hap made this really great mounting plate with his CNC machine. Makes a flawless fit in the portable.