exxos's Atari, Amiga & retro forum

Hello again it's me :lol:

Once the TOS upgrade was done, I wanted to install the RAM ugrade in my 1040 STF.
But all i have now is a screen with a white border and a black center.
Before removing the 32 RAMs (that's the only option left i see), I wanted to know if everything was good or if I had forgotten something?
I also tried to remove / set MMU RAM PCB back in place. No Luck.

Step 1: Step 2,3,4 soldering, cutting : Step 5,6,7 : Fitting MMU RAM PCB and connecting it to the Shifter Adapter Step 8,9,10 : Old RAM isolation Final Step : It should work but it does not :roll: Thanks - again - for your help :)

It seems that you soldered the turned pin strips upside down. You shouldn't have to cut the pins after you solder it. Since the the pins are a bit to thick now you might find it difficult to push down in the socket. It seems that it is not pushed down enough in the pic.

Is the MMU adaptor fitted correctly and pushed down enough? No broken pins? You have to fiddle a couple of times until it slides down further into the socket. And I hope that the MMU is still fitted in the socket underneath?

Often it's just bad connection somewhere.

As said above the pins are upside down. I don't know if they will make good contact in the shifter socket. Best thing is to remove the ram board, connect the resistors back up, and see if your machine boots and verify your video is working correctly first.

DoG wrote: 13 Oct 2019 20:57 It seems that you soldered the turned pin strips upside down. You shouldn't have to cut the pins after you solder it. Since the the pins are a bit to thick now you might find it difficult to push down in the socket. It seems that it is not pushed down enough in the pic.

You're right. I did it to have more space above. It fits quite well.

DoG wrote: 13 Oct 2019 20:57 Is the MMU adaptor fitted correctly and pushed down enough? No broken pins? You have to fiddle a couple of times until it slides down further into the socket. And I hope that the MMU is still fitted in the socket underneath?

It's in place. I tried to remove it (the MMu adapter) gently and put it back in place : Same problem.

exxos wrote: 14 Oct 2019 00:08 As said above the pins are upside down. I don't know if they will make good contact in the shifter socket. Best thing is to remove the ram board, connect the resistors back up, and see if your machine boots and verify your video is working correctly first.

Thanks Exxos. I followed your advice and the ST works fine with the resistors back in their original place, the shifter adapter but without the RAM "MMu adapter" board.
What's the next step ?

It might pay you to remove the MMU and check and clean the pins with IPA. You have to remember that this MMU adaptor is designed to fit in what is essentially the wrong side of the socket pins, so a pin that's distorted or dirty wont help matters much.

I've used two of these exxos 4mb upgrades and they do work very well but with some socket tweaking at first in my machines.

A white border and black centregenerally means that no RAM is avaiable, and that is often because of poor MMU contacts.

I'd suggest you clean the socket pins, and the chippins, and follow my guide to tweak the contacts like this https://www.exxosforum.co.uk/forum/viewt ... 094#p16094, and make sure it is all good before attempting the upgrade.

Make sure you sort out the Shifter adapter pins,as if they are too short you will have a problem.

If tou still get a black screen with white border, it's almost certainly something to do with the contacts in the MMU socket, so you'll need to work out what is going on.

Remember they don't plug between the socket and chip, but around the outside of the edge of the contacts, or you'll likely have poor connectivity.

Thank you rubber_jonnie & PhilC. I followed exactly what you said.
Then I put all the things back where they belong...
Same result: Black screen, white border.
It's killing me :roll:

Ok. So I tried to swap :
- the shifter adapter and the RAM "MMu adapter" board from a previously upgraded STF : Same problem on the same STF board. At least it's not a problem with exxos kit.
- the PSU : Same problem.
I also tried (for the 4th time) to clean with IPA and a needle the MMU pins : Same problem. black screen/white borders.

Heres the 2 boards i used :
The C070789-001 rev. B does work with both kits.
The C070789-001 rev. D doesn't work with both kits.
They look similar but maybe there's something else to change ? (see below the animated GIF to compare)
Anyone want to try to fix it? Clearly, it's beyond my electronic skills. :cry:

If you have a SR98 PSU, they have a 5V adjust. Try making sure its at 5V. You can try between 4.8V and 5.2V. You may need to change the address & databus resistors to 2.2K.

Also can you please edit your post and upload images to the forum and not link to external sites.. as when those images vanish , the thread will make little sense to people with the same issues in the future :)

exxos wrote: 20 Oct 2019 22:12 If you have a SR98 PSU, they have a 5V adjust. Try making sure its at 5V. You can try between 4.8V and 5.2V. You may need to change the address & databus resistors to 2.2K.

I tried with a Mitsumi SR98 PSU : 4.86 (the lowest it can do), 5.0 and up to 5.2v too : Same thing.

exxos wrote: 20 Oct 2019 22:12 Also can you please edit your post and upload images to the forum and not link to external sites.. as when those images vanish , the thread will make little sense to people with the same issues in the future :)

OK but i can't edit my previous posts :?