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Problems with IIsi and Portrait Display


Active member
Surprise surprise!

After tearing apart the SUN cable here's what I found out:

- the three coaxial cables are properly connected to the three coaxial connectors (A1->Red, A2->Green, A3->Blue)

- shell is connected to ground

- pins 1,3,4,5 are connected to cables Yellow, Orange, Brown and Red

- Black and Green cables are not connected to anything (!)

- pins 2,6,7,8,9,10 are not connected to anything (!)


So I guess I'll have to get a 13W3 connector and connect the missing cables.... :-(



Active member
As you might have already guessed, that was a 13W3 to VGA cable, that's why a few cables are missing.

I'll try with a proper 13W3 to 13W3 cable, I have one somewhere...



Active member
I finally got the cable!

The data I have so far are:

- Apple 13W3


- Apple DA-15

2018-12-20 21_52_35-Ports and Pinouts.jpg

- Sense codes for the Portrait Display

2018-12-20 21_52_04-Macintosh Video to VGA adapter pinout and wiring @ old.pinouts.ru.jpg

My questions are:

- is Comp/Hor/Ver *return* on the 13W3 equivalent to Comp/Hor/Ver *ground* on the DA-15?

- I guess I have to ground pin 4 to let the OS know there is a Portrait Display connector, right? In that case, is it pin 4 on the DA-15 that should be grounded?

Hope jt has had a chance to buzz his cable. 



Portrait Cable Pinout.JPG

Sorry it took so long. This is what I came up with. Haven't tried to figure anything out, just buzzed the connections for raw data. You're looking at the pins on the ends of the cable.

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Active member
Thanks you so much jt, I'll try to build the cable as soon as possible.

That pin-out makes very little sense according to the schematic I've found but I guess we'll have time to figure that out.



The cable buzzing data appears to match this pinout table.

View attachment 25702

View attachment 25721

Dunno about the sense pins. Do a markup of my drawing with the 13W3 pins numbered, that would have been my next step, but I ran out of time.

Just realized that I buzzed a black cable so it's probably the one ostensibly for Portrait AND TPD, but only worked as TPD. One of the engineers at the mfr. worked out the adapter pinout  while I was on the phone with him. I could all but see him leaning back in his chair with his eyes closed flipping sense code connections around in his head. The sense codes in my doodling work out to the be for the Apple 21"(?) grayscale TPD.

ISTR having a gray Apple cable in the spot behind the Portrait where the black cable was and there appears to be a gray cable in the pic above. I'm guessing the real deal is in a project box with the adapter. A couple of wires got knocked loose. Setting up to fix that would explain much.

You can go ahead and build the screw down connector as in my diagram and you'll probably see the 21" image with the "Portrait Scrunch" for confirmation. It might also display correctly as the cable's packaging was labeled as dual purpose.

Pink highlighting makes one of the pins an independent ground reference. using it to pull one of the sense pins low on boot could have been one correction we made and using whatever sense pin was high to correct another mismatched sense signal would have been the converse.

My adapter was a cut down M-F DB-25 adapter with sockets and tinned wire jumpers from Radio Shack. Your screw down terminator block connector would work the same way with oh so much less hassle.

edit: post enough of you sense code chart to show the TPD sense codes and we'll have the starting point for noodling out the "adapter" for my black cable.

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Active member
I have just tried that pin-out and the monitor stays black.

Just to make sure I got things correctly:

- I connected the three "pink" wires on the 13W3 together and then connected them to a single wire that goes to pin 11 on the DA-15

- I connected the two "blue" wires on the 13W3 together and then connected them to a single wire that goes to pin 4 on the DA-15 and then connected pin 4 to pin 7.

Is that correct?



Well-known member
I toned out my portrait display cable a while ago for another member.  It's a little different than what jt posted.  Mainly the outside barrels are swapped, and there is no short between pin 4 and pin 7.  Drawing is while looking at the cable ends.


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View attachment 25721

That's very odd about the coaxial connector swap, but makes no nevermind on a grayscale display. You're running RGB tied together(?) and it shouldn't matter which is which I would think.

The pink critter on my diagram is the same connections to pin 11 that you show on your diagram, it just looked different to me for a bit.

The cable I buzzed is definitely set up for the 21" Two-Page Grayscale Display, having 4 and 7 tied together. They must be Sense 0 and Sense 1.  For the Portrait Sense 1 needs do be in the same state as Sense 2.

The three tables below summarize the contents of this tech note.
Table S-1 Sense Line Code Assignments
Monitor Type Sense 2 Sense 1 Sense 0 Frame Rate (Hz)
------------ ------- ------- ------- ---------------
RGB 21" 0 0 0 75.08
Full-Page (B&W 15") 0 0 1 75.08
RGB 12" 0 1 0 60.15
Two-Page (B&W 21") 0 1 1 75.08
NTSC Monitor 1 0 0 59.94
RGB 15" 1 0 1 75.08
Hi-Res (12-14") 1 1 0 66.67
Multiple Scan 14" * 1 1 0 See Table 1
Multiple Scan 16" * 1 1 0 See Table 1
Multiple Scan 21" * 1 1 0 See Table 1
No Display Connected 1 1 1 NA
PAL Encoder * 1 1 1 50.00
NTSC Encoder * 1 1 1 59.94
VGA * 1 1 1 59.94
Super VGA * 1 1 1 55.98
RGB 16" * 1 1 1 74.55
PAL Monitor * 1 1 1 50.00
RGB 19" * 1 1 1 74.93

View attachment 25702

It's just stupid to have Monitor ID, bit 1-3  in one place and Sense 0-2 in another.

There's also the diode complication thing, is that rearing its ugly head in this cable build? Test for it?

Visiting the rugger up in Philly for a few days, I think I remembered where my Apple cable and the converter for the Black Griffen cable are hiding along with the incomplete switchbox.

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Well-known member
I wouldn’t think we would need to bother with sense bits?  Shouldn’t the monitor take care of that?  I mean, if we were trying to force different resolutions on a 3rd party display, sure... but this is Apple hardware to Apple hardware.  No?

Funny, when searching Google, Apple still has technical information posted on the portrait:


EDIT:  Found the cable pinouts in the Apple Peripheral Interface Guide.  Looks like there’s a typo in that the column headers are reversed, but it matches my tone out.  No mention of a diode.


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Active member
It's working!



I realized I made a mistake in mapping my cable *right before* applying the joethezombie's pin-out so maybe even jt's pin-out might work.

Thank you so much guys for your help, I'll try to solder a proper connector during the holidays. By the way, the IIsi you see in the picture has been used up to mid-1992 in a electronic engineering faculty of an Italian university, it is loaded with ClarisCAD too....



Fabulous! You've got the perfect height base for the only display that makes sense to use on the IIsi's pathetic 1MB frame buffer Vampire Video as it was set up for productivity in CAD rather than gaming. Did the NuBus Adapter and card come installed in the IIsi?

I'll buzz my cable again for boo-boos and the proper one as well. Looks like the Pink Critter version is the way to do it. I'm wondering if the sense lines matter only in third party VidCards. Joe, is yours an Apple cable?

ISTR the diode may (only?) be necessary in a VGA conversion.



Yes it did. If only I could find a Portrait Video Card.... I already have the original cable and the adapter card... :-(
Since you have the Portrait and IIsi with the  NuBus Adapter/GS TPD Card with Claris CAD on the HDD, I think what you're missing the Portrait Cable to built in video cable and the TPD display from 3PD GS CAD seat. I'd guess that the IIsi was configured with handmedowns from a IIfx/expensive CAD seat program that was upgraded to color TPD(s).

I ran across PC side cable build info to adapt the gorgeous Apple GS TPD to VGA connections on the PC, If I were you I'd look into goinag from 13W3 to VGA on an appropriate modern multisync panel leaving the Portrait at 4bi GS off vampire video.



Active member
You are right, the IIsi was probably dismissed by the faculty after getting newer equipment.

I know that a modern panel would look awesome but I prefer to have a period-correct system.

The icing on the cake would be getting a real Portrait Video Card....



Well-known member
I have two, one with DB15 (tested working, VRAM complete) and one with 13w3 (untested, as I don't have the cable).

PM me if interested in one or both.


photo 2.JPG