exxos's Atari, Amiga & retro forum

I finally got around to installing the excellent Exxos 4mb upgrade into a Maga2. But all I get is white border/black screen indicating a ram issue, i think.
Can some of you Experts take a quick look at my pics and see what might be wrong. The machine booted to the desktop before I started all this.
Here is a link to his page about the upgrade.
https://www.exxosforum.co.uk/atari/last/4MBMMU/index.htm
I got it many years ago, and he did the soldering of the ribbon cable connections. I did the Shifter board. (not too bad, if can say so myself)
I think the ribbon cable is upside down in the picture. If it is flipped, I get a full black screen, no border. The MMU pins fit very snug and level on the three sides. There is about a 1/16"+ gap between the mmu socket and the bottom of the mem-board. It will not go down any further.
Suggestions?
Thanks

Yep, cable is upside down.

Yep, Cable is upside down and looking at the Shifter adapter I think you have it 180 degrees out.

The writing on the cable should be uppermost with the bare metal contacts facing upwards on the cable. Otherwise no contact where you plug them in.

The Shifter adapter needs to have the cable connector pointing to the back of the machine.

I've compared to a picture of my own installation in a 520ST, and pin 1 of the Shifter should be on the edge of the adapter that has no connections or components.

Pull the Shifter from the adapter, plug the adapter back in with the cable connector at the back. Plug the Shifter into the adaptor, making sure the pin 1 'dot' matches the correct original orientation it would have in the mainboard if the adapter were not present. This should match the DMA next to it.

Plug the MMU adapter back in, this was correctly positioned in the first place, then connect the cable at both ends with the blue band down and the words/contacts facing up.

Should then work.

EDIT:

Here's a link to the picture of the same upgrade installed in a 520ST. https://www.exxosforum.co.uk/forum/viewt ... 4MB#p37858

I know it isn't the same mainboard, but you should be able to get enough detail of the Shifter adapter to correctly orient it with the Shifter and it's socket.

You can see the notch in my Shifter, indicating where pin 1 is to the left of the notch at the end of the chip, has pin 1 on the side of the board with no connector, but you have pin 1 on the side with the connector.

Good catch by @rubber_jonnie the shifter board is indeed in backwards.

exxos wrote: 11 Aug 2020 12:51 Good catch by @rubber_jonnie the shifter board is indeed in backwards.

I aim to please :)

:girldance: :girldance: :girldance:

That did it!
It works, and passes diagnostics ram test!! See the green on the screen!
Thanks everyone. Much appreciated !!
Exxos might want to explain this a little better on that install guide for Maga's.
But I'm glad it works now.
Thanks again for the sharp eyes on the shifter!!
Now I have to pull the PSU out again and file a bit more on the PCB to make room for the shifter now moved back a few more mm's.

Cool, glad we got you over the finish line.

Funnily enough I bought one of these for my Mega4 when I thought it had bad RAM, but ended up not using it as it turned out to be bad traces at the CPU for D2 & D4, which I fixed. My 520 ST then became the lucky recipient of the upgrade, replacing a much older Marpet upgrade.

BTW, just as a guide, please try and put images inline, as if you have multiple images, if just added as an attachment, they all bundle up at the end of a post. If you place them inline, they appear in whatever sequence you need them in.

I've fixed your last post in that respect BTW.

Glad it's all working as expected. :)

FYI you may want to look at a Meanwell PSU like this:


They are overall smaller, have a cleaner output (Less ripple than an Atari device), generate less heat, and should fit inside the metal PSU tray profile so no filing required for the Shifter :)

I like the meanwell psu I use the medical ones alot and they take a brown out well

Tom

Very cool!!
Got a link to get that medical one you mention? and a pic of how to wire it up, and secure it to the base plate?