Atari ST hardware problem

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revival
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Atari ST hardware problem

Postby revival » Sun Aug 05, 2018 11:02 am

Hello,

I got an atari ST in non working state and here is what is gives. Looks like some ram chips have
been put on sockets ?

Do you know what is the source of the problem ? I would love to give it a new life :oops:
thank you very much for the help

Image
Image
Last edited by revival on Sun Aug 05, 2018 5:45 pm, edited 1 time in total.

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Re: Atari ST hardware problem

Postby Mug UK » Sun Aug 05, 2018 2:44 pm

The images aren't showing up? Reupload and reattach to your original post.
My main site: http://www.mug-uk.co.uk - slowly digging up the bits from my past (and re-working a few): Atari ST, Sega 8-bit (game hacks) and NDS (Music ripping guide).

I develop a free Word (for Windows) add-in that's available for Word 2007 upwards. It's a fix-it toolbox that will allow power Word users to fix document errors. You can find it at: http://www.mikestoolbox.co.uk

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Re: Atari ST hardware problem

Postby revival » Sun Aug 05, 2018 5:48 pm

post updated sorry

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Re: Atari ST hardware problem

Postby Mug UK » Sun Aug 05, 2018 8:45 pm

revival wrote:post updated sorry


No need to apologise. It just helps you get our experts to help you out a bit quicker (if they can).
My main site: http://www.mug-uk.co.uk - slowly digging up the bits from my past (and re-working a few): Atari ST, Sega 8-bit (game hacks) and NDS (Music ripping guide).

I develop a free Word (for Windows) add-in that's available for Word 2007 upwards. It's a fix-it toolbox that will allow power Word users to fix document errors. You can find it at: http://www.mikestoolbox.co.uk

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Re: Atari ST hardware problem

Postby mlynn1974 » Sun Aug 05, 2018 11:48 pm

A similar board is shown here:
viewtopic.php?t=28426

So this should be a 512k ST? U32, U33, U34 and U38 look as if they are a different make of memory chip from the others so maybe someone had problems with this machine in the past and replaced those chips. Is this screen shown on boot? Video memory should start at $78000 on a half-meg ST so I think that the video memory would by default occupy memory chip U45 which is the same type as the majority of RAM chips on the board.

The display pattern is very regular repeating the same line every 160 bytes so maybe check the board for any track damage. Could it be that the video shifter chip is bad if there is no obvious track damage to the motherboard?
Still got, still working: Atari 4Mb STe, 520STFM, 2.5Mb STF.
Hardware: Cumana CSA 354, Ultimate Ripper, Blitz Turbo, Synchro Express II (US and UK Versions).

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Re: Atari ST hardware problem

Postby siriushardware » Sun Aug 05, 2018 11:52 pm

Can't help you specifically with that fault but like mlynn1974 above I notice the socketed RAM ICs are a different brand to the original ones still fitted directly in the board. What this says to me is that someone diagnosed a RAM fault and started to change RAM ICs until the fault was fixed - at which point they stopped, or, possibly, decided to give up after already changing four RAM ICs with no change in the fault.

Those four sided sockets on the south east corner of the PCB are a common cause of trouble because their design means that the springy pins of the chip exert constant outward pressure on the sides of the chip socket, but there is no opposite and equal force acting on the outsides of the sockets, so over time the sides of the socket gradually bow outwards.

Try removing the metal clips and (carefully) removing and replacing those two chips one at a time.

I notice the shifter screening box has two bits of writing written on at different times. One is 'OK', the other is 'FS' which could signify 'Faulty Shifter'.

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Re: Atari ST hardware problem

Postby derkom » Mon Aug 06, 2018 4:45 am

FWIW, that the RAM in U24 has also been socketed, but has not been replaced with a different chip.

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Re: Atari ST hardware problem

Postby revival » Mon Aug 06, 2018 4:50 am

thank you very much !

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Re: Atari ST hardware problem

Postby revival » Mon Aug 06, 2018 5:21 am

i bought a new shifter ic and will wait for it first before checking the rams

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Re: Atari ST hardware problem

Postby siriushardware » Mon Aug 06, 2018 8:56 pm

revival wrote:i bought a new shifter ic and will wait for it first before checking the rams


For reference, unless you happen to be a playboy millionaire, always try the things you can try which don't cost any money first, such as removing and re-seating the socketed ICs. The idea that 'FS' might mean 'Faulty Shifter' was just a pure guess.

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Re: Atari ST hardware problem

Postby revival » Tue Aug 07, 2018 6:53 am

I know. I first swapped rams to check for any difference. Reseted the two custom chips, and even checked for the shifter ic.
All made no difference, this is why I bought a new shifter ic

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Re: Atari ST hardware problem

Postby SteveBagley » Tue Aug 07, 2018 7:11 am

It’s almost certainly a RAM issue — the pattern you are seeing is TOS's memory test and the machine crashing out before clearing the screen. I had similar problems with an STM (see viewtopic.php?f=15&t=27414 ).

Steve

revival
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Re: Atari ST hardware problem

Postby revival » Tue Aug 07, 2018 9:17 am

Wow, thank you steve ! Let's give it a try while waiting for the shifter :)

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Re: Atari ST hardware problem

Postby revival » Fri Aug 17, 2018 5:47 pm

ok shifter is good and the socketed ram chips also.
time to put the other ram chips on socket...

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Re: Atari ST hardware problem

Postby revival » Fri Aug 24, 2018 12:32 pm

I put all dram chips on socckets, but it still doesnt boot. However, the behaviour seems stable. I bought not enough dram chips so I used
some I desoldered.

Does anyone knows if it can work with only 256K on lower address ? I mean at least boot


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