C103253 REV.5 - STFM 1MB Upgrade

Upgrade your RAM from ST to Falcon.
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rubber_jonnie
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C103253 REV.5 - STFM 1MB Upgrade

Post by rubber_jonnie » Wed Apr 24, 2019 11:23 am

Hopefully if I have enough time tonight, I will be upgrading my C103253 REV.5 mainboard viewtopic.php?f=56&t=466 to 1MB from 512MB.

This board will be interesting, since it uses SMT RAM chips, which until recently, I have struggled to obtain. Thanks to a very generous donation of the required chips, I'm now in a position to get this done. Since it is one of my dev boards, it'll be good to have the extra RAM for some of the testing I've been getting up to lately with the beta IDE interface.

I thought therefore I should at least give an idea of what the operation requires, and what sort of difficulties to expect during the upgrade. Thankfully, as it goes, the SMT connectors on the chips, and the pads on the board are pretty large, so I don't think that will be too hard from a soldering perspective.

Pictures and details to follow.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by Icky » Wed Apr 24, 2019 1:09 pm

:thumbup: Looking forward to seeing the pictures RJ

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by rubber_jonnie » Thu Apr 25, 2019 12:13 am

I made a start tonight, but due to having to fix a problem with my IDS box at home, didn't quite get as far as planned, and I don't fancy starting to solder SMT ram chips at gone midnight when I have to be up at 07:00 for work tomorrow. Comes under the category of 'Bad Idea'!!

First stage with this particular upgrade, is to prep the board for the decoupling capacitors and resistors. For desoldering, I used an iron set to 370C, and fluxed desolder braid (Chem-Wick). I also have liquid flux handy just in case.

You'll find it's pretty rare for Atari to have not filled in empty holes on most motherboards, as you can see here in the marked areas:

Board_top.jpg
Board_top.jpg (169.49 KiB) Viewed 1047 times

The other thing you'll find with this model of mainboard, is that the resistor thru holes will desolder relatively easily in one go, but if you look at the bottom of the board:

Board_bottom.jpg
Board_bottom.jpg (132.02 KiB) Viewed 1047 times

You can see that the caps are attached to some pretty hefty copper planes. So what does this mean for the job?

Simply put, you will find that a most of the holes will not clear just by desoldering from the top side only, so do one side first, then flip the board over, and re-do the holes from the bottom.

A small number may not clear, so don't be afraid to add more solder in to help the old stuff out, and more flux if needs be. Be careful though, to not put too much heat into one spot at any one time. If a hole won't desolder, then go and do another whilst that one cools and come back to it later. This takes some of the risk of causing heat damage away, and Atari mainboards can have pretty fragile vias.

Next stage will be to work out how to solder on the chips, which will go in before the caps and resistors to give me room to work.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by rubber_jonnie » Wed May 01, 2019 2:28 pm

So,it turned out there were only 14 RAM chips in the little baggy that arrived the other day, but thanks to the kind person who supplied them, I've just received another 16 freshly de-soldered chips, so I have more than enough for the job now.

Originally, I'd planned to solder them in by hand, but I have an opportunity to have a go at hot air soldering here, so solder paste is on it's way, so I'll hopefully get the chance over the next week to have a go, though I will have a bit of practice first to make sure I don't stuff up a perfectly good mainboard with too much heat.

Pictures will follow!! Hopefully with no scorch marks!
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by PhilC » Wed May 01, 2019 3:03 pm

RJ, I use Kapton tape to mask off anything i font want to come loose, so might he an idea to get some and tape up the existing chips.
If it ain't broke, test it to Destruction.

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by rubber_jonnie » Wed May 01, 2019 3:05 pm

PhilC wrote:
Wed May 01, 2019 3:03 pm
RJ, I use Kapton tape to mask off anything i font want to come loose, so might he an idea to get some and tape up the existing chips.
Not a bad idea. I had already considered that, but had no firm ideas on what i'd use up to this point.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by rubber_jonnie » Sat May 11, 2019 11:18 am

ADVICE PLEASE:

Ok, so I now have all the chips ready to go, I've had a little practise with a dead board, and have the temp right for non scorching of the PCB, but melting of the solder paste.

But I'm in need of some advice re the following:

1. Where is the best place to put the paste? On the PCB (This does look like the better option TBH, but would some sort of mask/stencil be recommended to evenly apply the paste) or on the chips (Fiddly, but maybe more accurate)?
2. What would you recommend to assist in getting the chip placement bang on each time. I figure some sort of jig, but am still mulling over my options.

Any and all advice very much appreciated, but in the meantime I will hit up the internet for any guidance I can find. I'm determined not to ruin the board with impatience!

Thanks all.
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by PhilC » Sat May 11, 2019 11:36 am

Morning RJ,

This is the way I do it.

I have a smaller needle on my solder paste syringe and apply it across the row of pads in a line, sparingly, as too much is a pain to remove on higher density pinned chips.

Then place the chips onto the pads in the right place and then use the heat gun. As long as the air isn't too strong the chips will stay in place just fine. Sometimes you'll need to tweak the location of the chips whilst heating them to just align them properly. But with the ones you've started with, I think you'll be fine.

You can then tidy up over soldered joints with desoldering braid or using flux and a larger flat bit to suck the excess onto the iron.

Of course using a stencil for the paste oven etc, will always be better but I've none if those myself.

Hope that helps and good luck.
If it ain't broke, test it to Destruction.

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by rubber_jonnie » Sat May 11, 2019 11:48 am

PhilC wrote:
Sat May 11, 2019 11:36 am
Morning RJ,

This is the way I do it.

I have a smaller needle on my solder paste syringe and apply it across the row of pads in a line, sparingly, as too much is a pain to remove on higher density pinned chips.

Then place the chips onto the pads in the right place and then use the heat gun. As long as the air isn't too strong the chips will stay in place just fine. Sometimes you'll need to tweak the location of the chips whilst heating them to just align them properly. But with the ones you've started with, I think you'll be fine.

You can then tidy up over soldered joints with desoldering braid or using flux and a larger flat bit to suck the excess onto the iron.

Of course using a stencil for the paste oven etc, will always be better but I've none if those myself.

Hope that helps and good luck.
Hey Phil, funnily enough I just watched a vid that did it exactly as you described, and have used a similar method to clean up using solder wick before when I did a very finely pitched IC with a normal soldering iron. If I can avoid wicking afterwards I want to, since the pads aren't actually that close together, and they are quite big. I think part of the problem is that I have a tub of paste, and whilst it would be pretty easy to transfer to a syringe, I'm not sure I have one that is suitable. As I said, I don't want to ruin the thing with my impatience, so I'm off to try and find a syringe, or if not, I will just have to buy one.

Advice appreciated as always :)
Collector of old Atari things:
800XL + Ape Warp mod, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg) + Gotek, 1040STFM + Vortex ATOnce + Gotek, 1040STF long button floppy, 4160 STE with Gotek and ROM switcher, 4160STE with 32Mhz booster, ROM switcher and CosmosEx, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: C103253 REV.5 - STFM 1MB Upgrade

Post by PhilC » Sat May 11, 2019 11:58 am

If you struggle finding one RJ, I can probably post you one but probably wouldn't be till next weekend.
If it ain't broke, test it to Destruction.

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