[PICS] Exxos 4Meg RAM card fitting - with soldered shifter

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[PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby spiny » Sun Mar 27, 2016 9:42 pm

Hi All,

heres a few pics showing the fitting of one of the Exxos 4 Meg RAM cards. Normally the shifter is socketed on STs so the only soldering that normally needs doing is to build the kit. However, I appaear to be unlucky as most of my STs have soldered shifters, which is a pain. On a previous ST, I desoldered the shifter, socketed it and went from ther, but this ST was 'broken' - general consensus was that the onboard RAM was bad, but it wan't 100%, so I didn't want to waste time on desoldering this shifter in case I broke it, so this install is a slight 'bodge' where I just soldered a socket on top of the shifter and plugged the upgrade into that. Turns out it was bad RAM and the upgrade fixed the ST :)


The Kit:
Image

Flexi cable socket installed - check very carefully to have all pins working, if you get the 'white border, black screen' when booting after fitting the kit, you probably missed a pin
Image

Soldered shifter:
Image

Resistors that need pulling up to disable onboard RAM
Image

Pulled up (this was a 1meg ST, so has more to disable)
Image

All connected to +5v
Image

Shielding removed for ease of access:
Image

Legs tinned:
Image

And kit fitted - for some reason I didn't take a pic of the socket soldered to the shifter.
Image

Doing it this way means the shielding no longer fits over the shifter, so I left it off.

cheers :)

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby exxos » Sun Mar 27, 2016 10:03 pm

spiny wrote:Doing it this way means the shielding no longer fits over the shifter, so I left it off.


Nice, congrats :) :cheers:

I should point out that Spiny's method isn't the "official" way of fitting it :) Where if everything is soldered into place without sockets, it fits fine in the shifter can.

Now you should really remove all that old DRAM ;) Oh, and put a nice fold in that ribbon cable ;)
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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby TheNameOfTheGame » Sun Mar 27, 2016 10:20 pm

Nice job! Glad you got the ST working again!

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby Bikerbob » Tue Oct 08, 2019 3:20 am

I need help with this one.. 520st.. no row of resistors and R59, R60,R61 are not all the same value on this board.

How do I know what resistors to pull and run to 5v?

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby DoG » Tue Oct 08, 2019 4:31 am

Bikerbob wrote:I need help with this one.. 520st.. no row of resistors and R59, R60,R61 are not all the same value on this board.

How do I know what resistors to pull and run to 5v?

What motherboard revision do you have?

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby Bikerbob » Tue Oct 08, 2019 4:56 am

REV H --- I think its R133 and R134 but with just those 2.. do I tie the ends of the resistors together and to the 5v?? I saw this..

https://atari.joska.no/520stm/4Mb%20RAM ... 0520ST.pdf and thats how I found the above resistors.. but I am not sure how I tie them to 5v now.

James

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby spiny » Tue Oct 08, 2019 6:59 am

Bikerbob wrote:REV H --- I think its R133 and R134 but with just those 2.. do I tie the ends of the resistors together and to the 5v?? I saw this..

https://atari.joska.no/520stm/4Mb%20RAM ... 0520ST.pdf and thats how I found the above resistors.. but I am not sure how I tie them to 5v now.

James



I have a 520ST that I did a RAM upgrade on I think, it was a while ago though so my memory is hazy :) I think I know where the machine is, i'll find it and take pics.

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby spiny » Tue Oct 08, 2019 1:27 pm

OK dug it out of storage, it looks like there are only two resistors that need linking to +5v: R134 and R133

Overview:
IMG_20191008_142046648.jpg


(this ST has a Monster card too)

5v supply:
IMG_20191008_142108394.jpg


R134 lifted
IMG_20191008_142052653.jpg


R133 lifted
IMG_20191008_142103354.jpg


hope this helps.
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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby Bikerbob » Wed Oct 09, 2019 2:46 am

So I did the exact same thing.

This forum is very frustrating.. all my file sizes are under 500k as per rules, and it will still not allow my pics to be uploaded.
screen.jpg
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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby Bikerbob » Wed Oct 09, 2019 2:48 am

20191008_223504.jpg
20191008_223501.jpg
20191008_223454.jpg


Now, I get nothing but a Black screen.. when I did not pull up the resistors I had 2.5meg and the machine worked fine.. now nothing.

James
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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby joska » Wed Oct 09, 2019 8:32 am

Bikerbob wrote:Now, I get nothing but a Black screen.. when I did not pull up the resistors I had 2.5meg and the machine worked fine.. now nothing.


520ST, right? I don't know this RAM expansion, are there any jumpers on it? Because it sounds like there's no RAM in bank 0, which is required for the ST to boot. With the original RAM enabled you had atleast 0.5Mb there.

It's also possible that there's a conflict between the onboard and expansion RAM. You could try pulling the RAS-line to the onboard RAM high as well, like you've already done with the CAS-lines.
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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby Bikerbob » Wed Oct 09, 2019 12:40 pm

Well I removed the upgrade.. have been running memory tests all morning.. its not the machine its the ram expansion. I have no idea if I have managed to damage anything.. my bench is anti static matted, and I have been doing electronics etc for the 40 years. So I have a good idea of what I am doing.

I will admit that I rushed the install - not pulling the resistors to disable the onboard ram. Maybe that damaged the ram in the expansion?

Anyway.. contacting exxos now to see what we can work out on an exchange.

I guess --- worst case.. if I leave the onboard enabled.. I could run this as a 2.5mb machine??

James

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Re: [PICS] Exxos 4Meg RAM card fitting - with soldered shifter

Postby Bikerbob » Wed Oct 09, 2019 12:46 pm

spiny wrote:OK dug it out of storage, it looks like there are only two resistors that need linking to +5v: R134 and R133


hope this helps.


thanks.. as posted I have removed the upgrade.. machine is fine.. something was either bad when I got it.. or I damaged something I guess.

Anyway.. I see several upgrades on that machine. I was selling (SOLD) this machine to a friend and he wanted to do lots of stuff as far as mods etc.. he is a coder I am the hardware guy.

I would love to see that picture with everything in it pointed out.. so I can show him.

2 - that pic of the upgrade would be important as the orientation of the upgrade on the MMU is not the same as Exxos shows. So showing the 520ST model which is a great candidate for the upgrade.. would help people I am sure.

James


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