parabellum wrote on 2024-11-14, 13:38:

Progress!
just got two kmm5361003cg-7 sticks, installed it alongside 30 pin dimms, and IT POSTED

Remaining problems : keyboard does not work, wrong ram size - 8MB missing

For troubleshooting keep it as simple as it can be, that means don't mix 72-pin and 3-pin SIMMs. Many times something you can't think of is causing issues and makes the whole process unnecessarily complex.

Dorunkāku wrote on 2024-11-14, 15:27:

There is no RAM problem.
He has four 1MB 30 pin SIMs and two 4MB 72 pin SIMs. That is 12MB total.

you are indeed correct. 72pin sims are 4MB each. 4+4+(1+1+1+1)=12MB
As for the broken keyboard port, i desoldered the keyboard controller to see which traces go where. to my surprise, there was a lot of corrosion and broken traces. i fixed all of them, got 40pin dip socket in its place.
Unfortunately, keyboard is still not working 🙁

might get a new keyboard controller ic.

parabellum wrote on 2024-11-14, 16:56:

you are indeed correct. 72pin sims are 4MB each. 4+4+(1+1+1+1)=12MB As for the broken keyboard port, i desoldered the keyboard c […]
Show full quote

Dorunkāku wrote on 2024-11-14, 15:27:

There is no RAM problem.
He has four 1MB 30 pin SIMs and two 4MB 72 pin SIMs. That is 12MB total.

you are indeed correct. 72pin sims are 4MB each. 4+4+(1+1+1+1)=12MB
As for the broken keyboard port, i desoldered the keyboard controller to see which traces go where. to my surprise, there was a lot of corrosion and broken traces. i fixed all of them, got 40pin dip socket in its place.
Unfortunately, keyboard is still not working 🙁

might get a new keyboard controller ic.

As for the keyboard ⌨️, try to check the fuse next to the connector, see if it leads, if it is interrupted you have to replace it, in any case check that there are +5V in one of the pins of the connector, you will see that a trace leads to that fuse.

PC@LIVE wrote on 2024-11-14, 17:23:

parabellum wrote on 2024-11-14, 16:56:

you are indeed correct. 72pin sims are 4MB each. 4+4+(1+1+1+1)=12MB As for the broken keyboard port, i desoldered the keyboard c […]
Show full quote

Dorunkāku wrote on 2024-11-14, 15:27:

There is no RAM problem.
He has four 1MB 30 pin SIMs and two 4MB 72 pin SIMs. That is 12MB total.

you are indeed correct. 72pin sims are 4MB each. 4+4+(1+1+1+1)=12MB
As for the broken keyboard port, i desoldered the keyboard controller to see which traces go where. to my surprise, there was a lot of corrosion and broken traces. i fixed all of them, got 40pin dip socket in its place.
Unfortunately, keyboard is still not working 🙁

might get a new keyboard controller ic.

As for the keyboard ⌨️, try to check the fuse next to the connector, see if it leads, if it is interrupted you have to replace it, in any case check that there are +5V in one of the pins of the connector, you will see that a trace leads to that fuse.

it is ok. I do suspect it is not a "fuse" but a wire with ferrite material around it - just like all the other inductor on this MB.

I pulled a compatible keyboard controller from "gonna fix it someday" pile of motherboards- NEC J8M42C -and it works flawlessly.
Thanks to everyone - Truly, you guys are the best 🤣
I will make an entry on The Retro Web.