WIP - exxos 4MB RAM upgrade on MEGA ST1

Upgrade your RAM from ST to Falcon.
Post Reply
User avatar
Marsupilami
Posts: 47
Joined: Tue Apr 03, 2018 5:55 pm

WIP - exxos 4MB RAM upgrade on MEGA ST1

Post by Marsupilami »

I'm trying to upgrade my MEGA 1 with the great Exxos KIT #35.
It's my first attempt so i may have made some mistakes :?

First the kit out of the box :
20190705_184518.jpg
20190705_184518.jpg (238.06 KiB) Viewed 3774 times
Then reading the links provided may help. Yes, well...if you know what is the part number of the components like shifter, glue etc...If you don't have any idea, search the part numbers with google. I found mine here.
The Mega 1 board
20190705_184546.jpg
20190705_184546.jpg (297.54 KiB) Viewed 3774 times
Before soldering :
20190705_184940.jpg
20190705_184940.jpg (240.69 KiB) Viewed 3774 times
Soldered (part 1)
20190705_195829.jpg
20190705_195829.jpg (194.06 KiB) Viewed 3774 times
Once soldered, the pins in the center needs to be trimmed (with cutting pliers) otherwise the 40 pin socket won't fit.
Notice the little component soldered to the pin 40 of the "shifter" (in my case CO70713)
20190705_200333.jpg
20190705_200333.jpg (254.03 KiB) Viewed 3774 times
Remove this component from the shifter. We'll need to solder it again to the kit later. Then remove the shifter.
20190705_201210.jpg
20190705_201210.jpg (255.3 KiB) Viewed 3774 times
Solder the 40 pins socket to the adapter then put the shifter on it.
20190705_203907.jpg
20190705_203907.jpg (153.58 KiB) Viewed 3774 times
Now solder back the [hum...whatever] to the pin 40 of the kit once plugged into the motherboard.
20190705_204714.jpg
20190705_204714.jpg (207.62 KiB) Viewed 3774 times
Now you need to find the MMU, for me it was the "C100109". Notice that there is no number "26" or else written on the (or at least on my) my kit so you'll need a bit of imagination to find the good position :)
20190705_205734.jpg
20190705_205734.jpg (269.7 KiB) Viewed 3774 times
Gently push it into position.
20190705_210257.jpg
20190705_210257.jpg (188.55 KiB) Viewed 3774 times
Now add the cable, take care, it's not very long but it fits :
20190705_210627.jpg
20190705_210627.jpg (316.96 KiB) Viewed 3774 times
I hope i did everything the right way. If someone can confirm.. :)

But now...I'm stuck. I don't find the R59 and i don't know if i need to lift others R#...ie what am i supposed to do ?
If i don't find the good resistances to lift up, i will remove the existing RAM. But it's unclear for me. I mean just removing the 8 RAM chip is enough ? If i remove the 8 (only 8 so i suppose it's 8x128k) do i still have to remove anything else ?
20190705_211724.jpg
20190705_211724.jpg (263.02 KiB) Viewed 3774 times
Thanks for your help :)
https://www.atarinside.com : Atari 800XL in Europe France/Italy/Benelux/Deutschland/UK White&Silver plastic boxes : Dumps, Videos, Books, reference list / + / as usual high resolution pictures of the Atari 800 XL motherboards.
User avatar
exxos
Site Admin
Site Admin
Posts: 23499
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: WIP - exxos 4MB RAM upgrade on MEGA ST1

Post by exxos »

Have you read the install page ? http://www.exxosforum.co.uk/atari/last/4MBMMU/index.htm

MEGA ST resistors are listed on that page...
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
Marsupilami
Posts: 47
Joined: Tue Apr 03, 2018 5:55 pm

Re: WIP - exxos 4MB RAM upgrade on MEGA ST1

Post by Marsupilami »

exxos wrote: Fri Jul 05, 2019 9:45 pm Have you read the install page ? http://www.exxosforum.co.uk/atari/last/4MBMMU/index.htm

MEGA ST resistors are listed on that page...
Yes i did and it was really helpfull. But since the title is "OLD RAM ISOLATION MEGA ST" and the MB part # is different, i don't want to do any mistakes :)

So just to be sure, should i do like that (even if the MB rev # is different):
Image
or
Remove the 8 RAM chips.
https://www.atarinside.com : Atari 800XL in Europe France/Italy/Benelux/Deutschland/UK White&Silver plastic boxes : Dumps, Videos, Books, reference list / + / as usual high resolution pictures of the Atari 800 XL motherboards.
User avatar
exxos
Site Admin
Site Admin
Posts: 23499
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: WIP - exxos 4MB RAM upgrade on MEGA ST1

Post by exxos »

Marsupilami wrote: Fri Jul 05, 2019 10:18 pm But since the title is "OLD RAM ISOLATION MEGA ST" and the MB part # is different, i don't want to do any mistakes :)
The version of the board doesn't really matter, or the resistor numbers really.. its the location on the board which is the main thing.. so you can follow that image for initial testing.. once working, I would cut out the old RAM.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
Marsupilami
Posts: 47
Joined: Tue Apr 03, 2018 5:55 pm

Re: WIP - exxos 4MB RAM upgrade on MEGA ST1

Post by Marsupilami »

Ok thanks a lot, i'll try tomorrow. Once the old RAM removed, should the resistors be kept with the 2 added wires or removed or be soldered back in initial state ?
https://www.atarinside.com : Atari 800XL in Europe France/Italy/Benelux/Deutschland/UK White&Silver plastic boxes : Dumps, Videos, Books, reference list / + / as usual high resolution pictures of the Atari 800 XL motherboards.
Post Reply

Return to “RAM UPGRADES”