Atari st520

[Pharo]

Hi all i know some of you are into old computing so I'm looking for some help.
I picked up an atari st today untested with a load of games got it home and to my surprise it actually loaded to the desktop and I thought I can't be this lucky and sure enough I wasn't, went to load a game and I get what I would describe as two bombs on the screen after about 20 seconds.
Is this a problem with the disk drive or something else and more importantly is it an easy fix.
Cheers Brian

 

[Vorbis]

Sorry for the AI

On an Atari ST, an error displaying two bombs means a Bus Error has occurred, indicating the Motorola 68000 processor tried to access an invalid memory address or experienced a hardware failure. [1, 2]
For a visual reference of a typical Atari ST display layout during system tasks or diagnostics:

Common Causes

• • Faulty RAM / Memory Upgrades: Poor soldering, damaged traces, or failed RAM chips/SIMMs often trigger bus errors.
  • TOS ROM Issues: Defective, unseated, or mismatched ROM chips (such as improper jumper settings when upgrading TOS versions).
  • DMA / Floppy Subsystem: Problems with the DMA chip, missing pull-up resistors, or disk controller communication failures.
  • Loose Custom Chips: Shifting or corrosion in socketed motherboard chips like the GLUE or MMU. [1, 2, 3, 4]

Troubleshooting Steps

• • Reseat Chips: Carefully press down on socketed chips and ROMs to ensure proper contact.
  • Remove Peripherals: Disconnect all external ACSI hard drives, cartridges, and floppy connections to isolate the base unit.
  • Check Modifications: Inspect recent RAM or TOS upgrades for bridged solder joints or incorrect wire placements. [1]

 

[Pharo]

Hi thanks for the post I read that one myself but didn't understand much of it 🤣 but it looks as if it needs opening up.
Hoping maybe someone has had this problem before and got it sorted.
Cheers Brian

 

[Vorbis]

Yeah, me neither sorry 😁

 

[Macro]

I once had an offical Atari bulletin about the ST that said (with it switched off) "lift it 3 inches off the desktop and then drop it."

I always found it easier to just open it up and reseat the chips myself, it was usually the multi pinned square ones rather than the roms.

 

[Pharo]

🤣 I'm a bricklayer 3 inches is just as good as 3 feet.

 

[Pharo]

Well I opened it up hoping to see something obvious but nothing it was remarkably clean to be fair, pressed all chips and roms put all back together and still showing the two bombs when trying to load a game 😡