Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

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alyre
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Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby alyre » Wed May 10, 2017 11:31 pm

I have a TT that has a floppy drive problem. I can see the file directory but cannot copy anything. The drive makes a repeated beep noise. The floppy drive works fine in my 1040ST. I can't get a drive emulator to work on the TT either, my first approach at trying to solve the problem. I did swap the floppy cable but that doesn't seem to be the problem. I do have a TT030 Diagnostic cartridge V1.5. Although the computer boots to desktop (hard drive attached and floppy drive attached) without the cartridge, all I get is a black screen with the cartridge plugged in. I have a second TT and the cartridge works fine on it. I swapped my MegaSte power unit but it didn't solve the issue but I have been having problems with my STE crashing consistently on boot. Perhaps two bad PSUs ? I hate pulling stuff out of my working TT, it has a memory board that I would rather not disturb. Could the cartridge be pulling enough power to result in a black screen ? There is an electrical shop in my city, should they be able to test it and replace components seeing how old this power unit is? The original power unit has the same model number as my MegaSte PSM-5341 but has an older sequence number C301379-001 and a back floppy drive connector than the traditional white. Not sure what the next step would be?

Thanks


Alyre

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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby rpineau » Thu May 11, 2017 12:09 am

Your TT might have the cartridge port fuse burned. If this is the case when you plug the cartridge it pulls all lines to LOW and would probably give you the black screen you see.
Check the fuse with a multimeter.
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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby Arne » Thu May 11, 2017 4:26 am

If you've got a 2MB ST-RAM card added then remove it and try again with the diag cart.

rpineau wrote:Your TT might have the cartridge port fuse burned. If this is the case when you plug the cartridge it pulls all lines to LOW and would probably give you the black screen you see.

Anyway: I've seen the inductor next to the fuse being blown on some TT, too.
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alyre
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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby alyre » Tue May 16, 2017 11:06 pm

Arne wrote:If you've got a 2MB ST-RAM card added then remove it and try again with the diag cart.

rpineau wrote:Your TT might have the cartridge port fuse burned. If this is the case when you plug the cartridge it pulls all lines to LOW and would probably give you the black screen you see.

Anyway: I've seen the inductor next to the fuse being blown on some TT, too.


Thanks for the help. I assume the fuse is close to the cartridge port. Does it have a location number on the mother board ? Any idea what amperage ?

Thanks

Alyre

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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby Greenious » Tue May 16, 2017 11:28 pm

http://dev-docs.atariforge.org/files/TT ... tic_p2.pdf page 6 contains the cartridge port

The fuse looks like it is 0.5A

Generally with wierd behaving Ataris, have you reseated all components? RAM?
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alyre
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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby alyre » Wed May 17, 2017 1:38 pm

Greenious wrote:http://dev-docs.atariforge.org/files/TT030_Schematic_p2.pdf page 6 contains the cartridge port

The fuse looks like it is 0.5A

Generally with wierd behaving Ataris, have you reseated all components? RAM?


Yes, that was my first step before I even plugged in the diagnostic cartridge. Does boot to desktop with working read write to the hard disk but has floppy disk access problems and the cartridge port. Will check out the fuse.

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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby alyre » Fri May 26, 2017 8:40 pm

alyre wrote:
Greenious wrote:http://dev-docs.atariforge.org/files/TT030_Schematic_p2.pdf page 6 contains the cartridge port

The fuse looks like it is 0.5A

Generally with wierd behaving Ataris, have you reseated all components? RAM?


Yes, that was my first step before I even plugged in the diagnostic cartridge. Does boot to desktop with working read write to the hard disk but has floppy disk access problems and the cartridge port. Will check out the fuse.


Hi again,

Thanks for the reference to the schematics. However, I don't have the background to link the fuse in question with the port. I have checked F61, in the attached photo and it is fine. Is this the correct one ? Could a problem with the floppy driver block the booting of the cartridge ? Anything else to check ? The machine does boot, and the hard drive is functional but not the floppy drive, a situation I could live with seeing I have a fully working second TT with more memory to boot.

Thanks - Alyre

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Re: Atari TT boots to desktop but black screen with diagnostic cartridge plugged in

Postby Greenious » Sat May 27, 2017 9:21 am

If you can verify that Vcc is present on the cartridge, and it still doesn't work, I'd suspect a broken cartridge connector at this point.

And no, if the machine is at all working, there is nothing able to stop that. Except perhaps a badly designed or broken card in the VME bus, but then again, the machine would probably not be working.

The diagnostic card also sends out diagdata on the serial port, if you connect it via nullmodem, you can get diagnostic data if it starts at all. But generally, if the TT starts at all, the screen wouldn't be black, it would be white, even if there is a RAM/graphics problem.
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