Add to NMS8250 third SLOT

Tal vez sea más fácil para publicar en Inglés

Here you can find an English version of SLOT3 : http://www.msxarchive.nl/pub/msx/docs/hwmodsetc/hanso/hwmodsetc/philipsnms82xxslot3.pdf
It's not the MY connector version, but an other one.

I'm also busy building a 3th slot in my NMS8250.
Just finished modding the 3th slot into the housing and i'm realy happy how it worked out.

I had to give up my 2nd drive, but on the other hand I hardly use diskdrives at all, so I wont miss it.

Probably you have noticed, that I'm finishing my unfinished projects
One of those projects is adding a 3th slot to a NMS8250

The mechanical part of the project I had finished almost 3 years ago, but the electronical part is still not finished. Somehow I cant get it to work, so I'm asking for help.

My goal is to get this to work using this instruction.

I prever this version above the MY connector version, because this version uses the buffers. But this makes it also a bit more complex.

I followed the entire instructions and getting a black screen. Then I found some comments

So I've added the pull-up resistors to the 74LS15 and the MSX boots up normaly, but none of the 3 slots work. When I replace te 74LS15 with the 74LS08, Slot 1 and Slot 2 works normaly.

I already found one thing in the instruction, that is wrong, so I'm wondering if someone else ever used this instruction and if this instruction has more errors.

The step (that I think) is wrong is :

The /BUSDIR signal needs to be on pin 10 and not 4 (SLTSL3.1)

Also I think the 3th slot needs to have it's own /INT signal, but i'm not sure.

What am I missing and/or does anyone knows how to achieve to add a 3th slot using the buffers?

Ok, so I can use the /INT provided from the 1st or 2nd slot. But still somehow it doesn't work.
Also the use of the 74LS15 is not clear to me, in orther schematics for slotexpanders I see that a 74LS21 is used to combine the BUSDIR signal of all 3 slots.

I wonder if it´s possible to upgrade a Sony HBF700 with a third slot. While examining my T600 (the Sony, not the Terminator one), which have a internal third slot connected the modem, it should be practicable. But this is another story I guess...