exxos's Atari, Amiga & retro forum

Hi, I am about half way on my journey to installing my 4MB upgrade on my REV F board (I removed all the ram today). I have a couple of questions.

1. Is it necessary to fill all the holes where the old RAM was with solder? On the pictures on the forum, they look like they are not filled. I have also seen some vidoes from Power Of Vintage, where he DOES fill the holes? Does it matter?



2. It looks like I need to install a resistor for RAS0. I was wondering if things will "work" without the resistor added for testing, and then do the mod for the resistor afterwards. In other words, I would prefer to limit the number of mods to the board during the upgrade, and do them one at a time.

3. It looks like I can hook up RAS0/CAS1L/CAS1L directly on the top part of the mother board (which is great). The diagram on the instruction page shows spots for CAS1H/CAS1L directly above RAS0. Why not use those instead of pins 136 & 137?

4. Are there any other general things to look out for when installing this upgrade?

Thanks everyone?

Paul

paulhocker wrote: 30 Dec 2024 07:03 1. Is it necessary to fill all the holes where the old RAM was with solder? On the pictures on the forum, they look like they are not filled. I have also seen some vidoes from Power Of Vintage, where he DOES fill the holes? Does it matter?

It makes no difference at all, other than it's harder to refit RAM in future as you'd have to suck the solder out.

In fact he's just not clearing out the holes after removing the legs of the removed chips.

I have no idea why he's removing the decoupling caps unless the pins on his RAM upgrade aren't long enough to sit on the board with them in place.

First off, as @stephen_usher mentions, there really is no need to fill the holes other than if you suspect a via is cracked and need to repair.

I would say that you should read and follow he installation instructions here: Installation instructions.

Also pay particular attention to the pin positions. Somebody on the forum tried to do one of these upgrades and got the pins aligned incorrectly, possibly damaging the ST and the upgrade. Pin alignment is critical, I can't stress that enough.

Power of Vintage here.

These folks are correct here. I probably just filled some holes to keep the board looking tidy. The biggest reason why holes were still filled is due to the way I removed the RAM here. I snipped the legs off the RAM chips and then heated the legs to carefully remove them. This leaves the solder in the holes.

I then remove solder specifically from the holes where the upgrade pins are located (occasionally removing some solder from adjacent holes).

You hit it exactly on the head, I removed the decoupling caps because of interference with the upgrade board.

Good luck on the upgrade! It's a great one.

Thanks for all the insight everyone.

Does anyone have any thoughts around my 2nd and 3rd question?

Really curious is I need to add that resistor to make the whole project "work" or if it just a nice to have?

Thanks.

2. for question 2, as per the instructions page, if you have a revision where it's required, put it in. If you try it without, it won't do any harm either.
3. Simply because there's about 10 different revisions of the STm motherboard and those areas aren't available on all. So the instructions are just for whatever revision was used at the time. Mine were all connected underneath the motherboard directly to the MMU solder pins.
4. Don't make the mistake 'Adrians digital basement' made, he installed sockets, then he couldn't put the machine back together again because his keyboard wouldn't fit. Strangely enough, this was years ago and he's never done a video rectifying it... (Link to Adrian's video) bare in mind, his is an older version of the upgrade pcb.

Thanks @Steve

For #2, thanks for that, I was more curious to see if it would harm things versus working.

For #3, again I was just curious if the pins are the same, I am going to use pins 136 & 137 respectively on the top of the board for CAS1 lines.

On #4, yes I watched his video, and thankfully I did. I was originally going to go with sockets as well.

Wish me luck!

paulhocker wrote: 30 Dec 2024 15:55 Thanks @Steve

For #2, thanks for that, I was more curious to see if it would harm things versus working.

For #3, again I was just curious if the pins are the same, I am going to use pins 136 & 137 respectively on the top of the board for CAS1 lines.

On #4, yes I watched his video, and thankfully I did. I was originally going to go with sockets as well.

Wish me luck!

If you have already removed the old RAM, then the most painful part should be done (on my machine ATARI had doubled the RAM by stacking and soldering it together and that was an experience to get it off the board...).

Aligning the pins of the new boards was a bit tedious until all pins are fitting, but once done - and if you secure the board with some tape for soldering - then its straight forward.

Thanks.

My board did not come with pins so I plan to use the method that @coonsgm and start in the middle and work my way out. Seems the most logical way to do it instead of putting all the pins on first and then trying to jam it in there.

Update:

Some good news.

1. I did not destroy my computer. So that was a relief. :)

2. SysInfo is now showing 2MB or RAM, not 4.

3. It appears that bank 1 is not showing. Is that the CAS1H line?

Here is a screenshot