Mega ST4 working but only showing 2mb

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Forgottenmyname
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Re: Mega ST4 working but only showing 2mb

Post by Forgottenmyname » Sun Apr 29, 2018 8:31 pm

Already set to 9600, 8 N 1.

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Re: Mega ST4 working but only showing 2mb

Post by exxos » Sun Apr 29, 2018 9:25 pm

Did you try 1MB selection on the DRAM board ? (can't remember sorry!)
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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Re: Mega ST4 working but only showing 2mb

Post by Forgottenmyname » Sun Apr 29, 2018 9:34 pm

Yes I did, forgot to post that.

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Re: Mega ST4 working but only showing 2mb

Post by exxos » Sun Apr 29, 2018 9:43 pm

Forgottenmyname wrote:
Sun Apr 29, 2018 9:34 pm
Yes I did, forgot to post that.
I take it it did not help?

Are all the address and data lines from the CPU to the MMU all continuity checked ? Maybe there's a bad connection in that area. As you basely replace the whole RAM circuit and the MMU, there well be a bad connection somewhere else. I also assume you have physically checked the socket itself for damage ?
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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Re: Mega ST4 working but only showing 2mb

Post by Forgottenmyname » Mon Apr 30, 2018 9:10 am

No it didn't help unfortunately.

The socket did have a lot of bent pins, which I have sorted out. I am starting to wonder if this is the cause, as prior to the ram removal everything worked, albeit at 2mb. The pins as is will make good contact with the MMU but I am wondering about the MMU adaptor, as there is a gap behind each pin in the socket now.

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Re: Mega ST4 working but only showing 2mb

Post by exxos » Mon Apr 30, 2018 7:59 pm

Forgottenmyname wrote:
Mon Apr 30, 2018 9:10 am
The socket did have a lot of bent pins, which I have sorted out. I am starting to wonder if this is the cause, as prior to the ram removal everything worked, albeit at 2mb. The pins as is will make good contact with the MMU but I am wondering about the MMU adaptor, as there is a gap behind each pin in the socket now.
It does squash the pins little bit, but I have not really had any issues with removing the board and going back to a plane MMU. But there is indeed less pressure on the pins..

What I would suggest is you can push the pins out on the MMU itself push them outwards slightly as reinserting them in the socket a couple of times does push the pins inwards on the chip itself which can cause bad connections.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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Re: Mega ST4 working but only showing 2mb

Post by Forgottenmyname » Mon Apr 30, 2018 9:26 pm

You mean push the pins on the actual chip out a little?

Wouldn't have thought of that, definitely worth a try :dualthumbup:

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Re: Mega ST4 working but only showing 2mb

Post by exxos » Mon Apr 30, 2018 9:57 pm

Forgottenmyname wrote:
Mon Apr 30, 2018 9:26 pm
You mean push the pins on the actual chip out a little?

Wouldn't have thought of that, definitely worth a try :dualthumbup:
Yes :) I have to do it all the time.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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Re: Mega ST4 working but only showing 2mb

Post by scott.clifford » Tue Nov 27, 2018 2:48 pm

Black screen with white border is exactly what I got when I removed a faulty mem upgrade and left my Mega ST1 with only 512k. It's looking for memory thst isn't there.
After I resoldered in the other 512k (making it a stock 1mb again) it ran to desktop without the black screen, white border. Only by making it 1mb

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Re: Mega ST4 working but only showing 2mb

Post by Forgottenmyname » Tue Nov 27, 2018 6:11 pm

Very true Scott, I dumped all 4mb and put in one of Exxos's ram boards. That Mega is suffering a lot with corrosion.

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