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Help with Atari 1040 STf


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If any of you have some words of wisdom I would appreciate it.

 

I acquired a large lot associated with an Atari 1040 STf (SF354, color and monochrome monitors, disk master, monitor master, GT-1000, SyQuest SQ555, Spectre GCR, MagicSac etc.) along with about 500 pieces of software. It has been stored for quite a long time but I was anxious to start exploring. The problem is I can't get it to boot. The power light comes on, but that is the extent. No sound from the internal floppy drive with a disk in it, no attempt to access the SF354 when connected. The image on the monitors does change as the power is turned on and off to the 1040 like the monitors are recognizing that a device is connected. Please excuse the ignorance of my questions, and hopefully I can learn something.

 

1) Is it possible that this unit was configured to boot from something other than ROM? Will it boot from ROM if those other devices are not connected or configured properly? I am trying to determine if I likely have a hardware issue as opposed to a configuration/connection issue.

2) What should I go about checking first, second, third, etc. since it seems that the power supply is working?

 

I have a digital multimeter and at least a rudimentary understanding of electronics.

 

Thank you!

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If any of you have some words of wisdom I would appreciate it.

 

I acquired a large lot associated with an Atari 1040 STf (SF354, color and monochrome monitors, disk master, monitor master, GT-1000, SyQuest SQ555, Spectre GCR, MagicSac etc.) along with about 500 pieces of software. It has been stored for quite a long time but I was anxious to start exploring. The problem is I can't get it to boot. The power light comes on, but that is the extent. No sound from the internal floppy drive with a disk in it, no attempt to access the SF354 when connected. The image on the monitors does change as the power is turned on and off to the 1040 like the monitors are recognizing that a device is connected. Please excuse the ignorance of my questions, and hopefully I can learn something.

 

1) Is it possible that this unit was configured to boot from something other than ROM? Will it boot from ROM if those other devices are not connected or configured properly? I am trying to determine if I likely have a hardware issue as opposed to a configuration/connection issue.

2) What should I go about checking first, second, third, etc. since it seems that the power supply is working?

 

I have a digital multimeter and at least a rudimentary understanding of electronics.

 

Thank you!

 

Does the image ever turn white on the screen?

 

I would check to see that all the chips are seated properly, and that the floppy and kb are connected properly

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I didn't check the kb but the floppy was connected properly. Thank you for your reply. The image does not turn white.

 

Which chips should be reseated, essentially all of them on the motherboard?

 

 

 

yeah, just make sure everything is secure. Maybe also check that no chips have been removed, like the ROM chips.

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I reseated all the chips and the only change I noticed is there is a small brief sound from the internal floppy at powering on.

 

I did learn that this computer has a Z-RAM upgrade. I posted pictures under the member gallery titled "1040 STf Repair". Not sure how to link those here.

 

What would be the next thing to check and/or replace? Thank you!

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PSU and the memory upgrade are probably the most likely next culprits to check. The PSU may (will probably) need a recap, and the memory board may need reseating (hopefully it won't have gone bad, but you will have to completely remove it to check if it has). You will need to check that the PSU output is correct, even if it looks like it is powering the ST, it might have all sorts of problems. Might be worth checking the caps on the motherboard as well.

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Thank you.

 

I thought if the LED was on that the PSU was okay but that was naive. I believe the output wires are red, red, black, black, black, blue. I will check the voltage output there next.

 

I am not familiar with the memory upgrade and how it is connected, so I didn't want to put too much force on it. Is the MMU socketed?

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Usually they (the memory upgrade) plugs in over the MMU, occasionally the pins can get dirty, or bent too far backwards to make good contact (they become more brittle with age). Sometimes, in the case of late STs the upgrade had to be soldered on top, but as you have a STF I would guess yours is socketed. If you can see only plastic casing rather than pins that would be the case. The bit of the upgrade that fits over the shifter has pins which are pressed down between the MMU and its socket so to remove you will need to carefully pull straight up (make sure it is socketed first though!). The other bit of the memory upgrade usually goes into the shifter box (the metal box), where it is either soldered on top or if socketed, the shifter fits into a socket adaptor, which then fits into the original socket. To remove this first take the adaptor out of the socket, then remove the shifter from the adaptor and replace this in the original socket.

 

Check both If the upgrade isn't soldered I would remove it to test the ST without another weak link. The MMU may need a replacement socket if this is the root cause as it will be hard to rescue one with weak connections. Another thing to note, if the ST is sporting 4mb then the original memory on the motherboard will have been deactivated by cutting some resistors, these will need to be resoldered if this is the case (as otherwise the ST will have no memory at all). Is the Z-ram kit a simm style kit or otherwise?

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