ALPHA MODIFICATIONS

STF clone project.
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exxos
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ALPHA MODIFICATIONS

Post by exxos » Sun Sep 09, 2018 9:27 pm

Started a new thread for "must do" fixes and mods etc.
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: ALPHA MODIFICATIONS

Post by exxos » Sun Sep 09, 2018 9:35 pm

JUMPER PADS
links.jpg
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SJ1 & SJ2 are the 2 solder pads like on the STFM near the blitter. Pads must be shorted when NOT using the blitter, and OPEN when using the blitter. For now I would suggest not fitting the blitter.

SJ5 is the clock line for the CPU, this needs to be soldered to allow 8MHz clock to CPU.

SJ3 & SJ4 Need to both be linked.

(Jumpers were there with intention of adding boosters without cutting tracks at a later date )

Jumper next to the ROM is the TOS104 / TOS102 select line.
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: ALPHA MODIFICATIONS

Post by exxos » Mon Sep 10, 2018 10:05 am

RESET FIX

First is the short as found by icky on the reset circuit viewtopic.php?f=19&t=1171#p9633


The red circle shows the resistor shorting out VCC to the highlighted yellow line..
1.JPG
1.JPG (55.25 KiB) Viewed 644 times

SOLUTION


STEP 1:
s1.JPG
s1.JPG (53.48 KiB) Viewed 644 times
Cut the tracks on the bottom of the pcb where the yellow lines are.



STEP 2:
s3.JPG
s3.JPG (56.88 KiB) Viewed 644 times
Solder a wire on the bottom of the PCB to join the pads highlighted with a yellow circle.

DONE:
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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Icky
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Re: ALPHA MODIFICATIONS

Post by Icky » Mon Sep 10, 2018 10:24 pm

exxos wrote:
Mon Sep 10, 2018 10:05 am
If anyone can post a image of this fix then it would help...
As requested two images. Excuse the messy soldering / flux etc on the underside :oops:

IMG_3034.png
IMG_3034.png (419.7 KiB) Viewed 610 times

Track cuts are under the wire patch

IMG_3032 (1).png
IMG_3032 (1).png (367.9 KiB) Viewed 610 times

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Re: ALPHA MODIFICATIONS

Post by exxos » Mon Sep 10, 2018 10:56 pm

Icky wrote:
Mon Sep 10, 2018 10:24 pm
As requested two images. Excuse the messy soldering / flux etc on the underside :oops:
:bravo:
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: ALPHA MODIFICATIONS

Post by exxos » Sun Sep 16, 2018 10:30 pm

HSYNC FIX

from here viewtopic.php?f=19&t=1146&start=90#p9961

I ballsed up the Hsync and it needs a fix to bypass the inverter...

d1.JPG
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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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Icky
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Re: ALPHA MODIFICATIONS

Post by Icky » Sun Sep 16, 2018 11:19 pm

exxos wrote:
Sun Sep 16, 2018 10:30 pm
HSYNC FIX

from here viewtopic.php?f=19&t=1146&start=90#p9961
I just sat down to start doing some work on the board tonight and thought I would tackle this first.

Fix in place but am still getting horizontal scrolling as per video of boot before fix.

Will take a closer look at the circuit to see whats going on.

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Re: ALPHA MODIFICATIONS

Post by Realloy » Sun Sep 16, 2018 11:55 pm

After cutting the trace on both sides of R920 ,,,, measure between D7 and the cut free R920 i get zero ohm, those two point must go to positive plane in pcb, so i guess no need to move the R920.

And also i noticed that the holes for the PSU is mirrored on the PCB.. Maybe you already know this..

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Re: ALPHA MODIFICATIONS

Post by exxos » Mon Sep 17, 2018 12:10 am

Realloy wrote:
Sun Sep 16, 2018 11:55 pm
After cutting the trace on both sides of R920 ,,,, measure between D7 and the cut free R920 i get zero ohm, those two point must go to positive plane in pcb, so i guess no need to move the R920.
ahh yep, The left link wire isn't needed as the resistor itself actually connects to vcc.. will update the info...
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.

Realloy
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Re: ALPHA MODIFICATIONS

Post by Realloy » Mon Sep 17, 2018 8:33 pm

i can see all the chips have a decoupling capacitor,,, but what about BAD DMA ? is there one and where? or is it not necessary?

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