Atari TT - Bus errors, advice needed! - SOLVED

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Steve
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Re: Atari TT - Bus errors, advice needed!

Post by Steve » Fri Aug 03, 2018 2:38 am

Okay, I have installed the new replacement cracked resistor & I have installed all the SIPs.

Result: No video output on either TT output or VME graphics output :O

* Notes, I can see the hard drive loading, so I think the machine is running, just without display.

Whats my next move, remove all the SIPS?

Here is a photo of my SIP installation:


Steve
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Re: Atari TT - Bus errors, advice needed!

Post by Steve » Fri Aug 03, 2018 10:42 am

edit

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exxos
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Re: Atari TT - Bus errors, advice needed!

Post by exxos » Fri Aug 03, 2018 10:45 am

Have you got pin 1 of the sips right way ? (normally square pads on pcb) and nothing shorting on the pins to pcb or to each other ?
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

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Steve
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Re: Atari TT - Bus errors, advice needed!

Post by Steve » Fri Aug 03, 2018 12:38 pm

exxos wrote:
Fri Aug 03, 2018 10:45 am
Have you got pin 1 of the sips right way ? (normally square pads on pcb) and nothing shorting on the pins to pcb or to each other ?
Okay fixed it lol. The SIPS were all fine, it was the resistors I soldered in to fix the cracked ones. I dunno why but they were causing the no display.

*update: Now my floppy drive works :) It is reading, writing and formatting perfect now. Also: ST ram test in Yaart passes no issues, also seems to go through the tests twice as fast!

So I'm getting there.. now I just need to work out what to replace the resistors with.. Here is a photo of the location, note the two missing resistors have a C designation, that is odd..

They are c218 and c220. They were: brown green brown silver silver.
I used these: http://au.element14.com/webapp/wcs/stor ... reId=10184
But obviously I must have gone horribly wrong?


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Re: Atari TT - Bus errors, advice needed!

Post by exxos » Fri Aug 03, 2018 12:49 pm

What exactly are you looking at ? "C" is normally capacitor not resistor.. Can you find those parts on the diagram ?
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

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Re: Atari TT - Bus errors, advice needed!

Post by Steve » Fri Aug 03, 2018 12:59 pm

Right above those blue thingy mabobs. I've removed them, the designations are there. Click full screen I added a comment and a box around them.

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Re: Atari TT - Bus errors, advice needed!

Post by exxos » Fri Aug 03, 2018 1:00 pm

Steve wrote:
Fri Aug 03, 2018 12:59 pm
Right above those blue thingy mabobs. I've removed them, the designations are there.
Can you find them on the TT schematic so we can see what they actually are...
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: Atari TT - Bus errors, advice needed!

Post by Steve » Fri Aug 03, 2018 1:17 pm

I've had a look but I cannot see them. Maybe Atarian Computing can help with that.

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Re: Atari TT - Bus errors, advice needed!

Post by Steve » Fri Aug 03, 2018 2:24 pm

I checked in this persons motherboard photo, on their revision H, they have two of the regular yellow ceramic caps in those places:
viewtopic.php?f=58&t=591

Where mine seemed to have those odd resistors, very strange :)

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Re: Atari TT - Bus errors, advice needed!

Post by exxos » Fri Aug 03, 2018 2:26 pm

Steve wrote:
Fri Aug 03, 2018 2:24 pm
I checked in this persons motherboard photo, on their revision H, they have two of the regular yellow ceramic caps in those places:
viewtopic.php?f=58&t=591

Where mine seemed to have those odd resistors, very strange :)
Well "old skool" capacitors did have colour codes like resistors.. just I haven't seen any for like 30 years :lol: :roll:

If you look online probably a calculator to convert the colours. Assume it be 100nF or something like that.. depends what its connected to..
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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