ALPHA MODIFICATIONS

Open source STF clone project.
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exxos
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Re: ALPHA MODIFICATIONS

Post by exxos » Mon Sep 17, 2018 8:36 pm

Realloy wrote:
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?
Theres 4 caps around the DMA already.. no need to add a 5th.. :)
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Re: ALPHA MODIFICATIONS

Post by Forgottenmyname » Tue Sep 18, 2018 10:45 am

For the sync fix I pulled both pins 8 and 9 out of the U51 socket and then jumpered the socket.

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Re: ALPHA MODIFICATIONS

Post by kodak80 » Tue Sep 18, 2018 11:07 am

Forgottenmyname wrote:
Tue Sep 18, 2018 10:45 am
For the sync fix I pulled both pins 8 and 9 out of the U51 socket and then jumpered the socket.
Do you have a photos of the change for us less technical builders? And did this resolve the sync problem?
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Re: ALPHA MODIFICATIONS

Post by Forgottenmyname » Tue Sep 18, 2018 11:13 am

Hopefully you can see it on here.

It didn't sort my sync problem but will work on that.
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Re: ALPHA MODIFICATIONS

Post by exxos » Tue Sep 18, 2018 11:28 am

Forgottenmyname wrote:
Tue Sep 18, 2018 10:45 am
For the sync fix I pulled both pins 8 and 9 out of the U51 socket and then jumpered the socket.
You shouldn't pull pin 9 because you will have 2 floating gates in the chip then due to disconnected inputs.
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Re: ALPHA MODIFICATIONS

Post by Forgottenmyname » Tue Sep 18, 2018 11:30 am

Ok will put 9 back in, good point

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Re: ALPHA MODIFICATIONS

Post by exxos » Tue Sep 18, 2018 6:15 pm

BR PULL UP FIX

Bodge wire 1... Wire the thick yellow drawn wire as shown on the back of the pcb...

(Fixing missing pull up resistor on BR).

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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

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Re: ALPHA MODIFICATIONS

Post by exxos » Tue Sep 18, 2018 6:23 pm

BGACK PULL UP FIX

Bodge resistor 1..... 2.2K between the 2 circled points on back of CPU socket...

(fixes missing pull up on BGACK)

f2.jpg
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Re: ALPHA MODIFICATIONS

Post by troed » Tue Sep 18, 2018 6:29 pm

exxos wrote:
Tue Sep 18, 2018 6:23 pm
Bodge resistor 1..... 2.2K between the 2 circled points on back of CPU socket...
I'm confused by this being connected to BR.

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Re: ALPHA MODIFICATIONS

Post by exxos » Tue Sep 18, 2018 6:32 pm

troed wrote:
Tue Sep 18, 2018 6:29 pm
I'm confused by this being connected to BR.
Its a missing pull up resistor on BR & BGACK.
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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