Rambank II by T. Heier installation

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Gleylancer
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Rambank II by T. Heier installation

Postby Gleylancer » Thu Jul 30, 2015 6:00 pm

I've recovered a completely busted Atari 520ST that had a Rambank II by T. Heier installed. However, as busted as the computer was, so were the cables of the Rambank II. When I turned the computer on, no extra ram would show up.

So I tried to completely rewire it. But whenever VCC is connected the screen is completely messed up. So I believe some of the wiring is wrong and I have no instruction on how it should be. Does anyone know this expansion? Maybe from old magazines or something. There should be instructions *somewhere* :)

Image

This is the wiring I wrote down:

(Left side of the board)
Right row:
1 - U16 Pin 3
2 - RASI
3 - U15 Pin 53
4 - R124 Bottom
5 - R123 Bottom
6 - R122 Bottom
7 - R121 Bottom

Left row:
1 - CASIL
2 - CASIH
3 - R125 Bottom
4 - R126 Bottom
5 - R118 Bottom
6 - R119 Bottom
7 - R120 Bottom

(Bottom side of the board)
Upper row:
1 - U27 7
2 - U27 9
3 - U27 12
4 - U27 16
5 - U26 3
6 - U26 7
7 - U26 12
8 - U26 14

Lower row:
1 - U27 3
2 - U27 5
3 - U27 14
4 - U27 18
5 - U26 5
6 - U26 9
7 - U26 16
8 - U26 18

sarnau
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Re: Rambank II by T. Heier installation

Postby sarnau » Fri Jul 31, 2015 10:24 pm

Hmm, einfach mal bei Thomas anfragen: http://www.thomas-heier.de und ihm Grüsse von mir ausrichten...

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Gleylancer
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Re: Rambank II by T. Heier installation

Postby Gleylancer » Sat Aug 01, 2015 1:31 pm

Thanks, I've sent him an E-Mail and I'm hoping for a reply :)

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Re: Rambank II by T. Heier installation

Postby Guest » Sat Aug 01, 2015 11:00 pm

fit a 4MB simm and a socket
easy stuff

look in the wiki

or ask alanH for his board not sure if he is making a run

replaces the board you have and ide and tos 2.06 etc for a small price

i feel if you replaced the cables and i feel your not daft
perhaps some ic;s have failed
so changing it for a many update board
simply first reverse the mod and fit something better instead
to a working 512K ?? machine??

if your determined
then if you have fried ram
you can add problems too your system

.... not easy too fix... :shrug:

i suspect some chips are fried
its not worth fixing it better to add a 4MB simm and a switch to give you 1MB instead for some games etc on st
if you fit alanh and perhaps others mods instead its a better use of your STFM that works!! past frying its chipset
in an attempt to repair a not very good upgrade... :shrug: dont shoot the messenger ... ioh

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Gleylancer
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Re: Rambank II by T. Heier installation

Postby Gleylancer » Sun Aug 02, 2015 8:41 am

You have no idea how much work I've already invested into this 520ST to get it back to normal. Rewired the keyboard, replaced switches, cleaned the case of all yelowing... Of course it's not worth it, you can get one of these machines for as low as 20€ on eBay.

But here's the thing: I like fixing things :)

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frank.lukas
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Re: Rambank II by T. Heier installation

Postby frank.lukas » Sun Aug 02, 2015 9:51 am

I think these are 1MBx1 Ram Chips and it is the same as in a Atari Mega ST2/4 for one 2MB bank (16 chips). See the wiring diagram from a Mega ST2/4.

There are two Ram banks, bank_0 has 0,5MB (original 520ST) and bank_1 has 2MB, so the total is 2,5MB Ram ...
fancy Atari Musik anDA Dance "Agare Hinu Harukana" 1998 ATARI http://www.youtube.com/watch?v=JX10fxb5eYE


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