exxos's Atari, Amiga & retro forum

I started a new thread for the install of the Alpha mod PCB..


STEP 1

Cut the DE track as shown below...

Solder a wire approx 4" as shown below.

(note to self, DE from GLUE also goes to MFP... ?)



STEP 2

Solder a wire as shown (about 8" length)



STEP 3

Lift the "top side" of the resistors as shown, bend upwards and solder some wires on (about 5" length)



STEP 4

Unsolder SJ5 and solder a new wire as shown below to R911 (about 5" long)

NOTE: There are 2 wires going to R911 (one is not yet connected to anything as will go to the mod pcb later)


VIEW FROM ABOVE OF THE LINK WIRE (R923 TO R911)
(I highlighted the wire with a thick red line)

STEP 5

Lift the ends of the resistors as shown.

The free end of R905 needs 2 wires.. 3" and 10" approx.



R905 3" wire solders to the free end of R903 as highlighted in red..



The 10" wire on R905 will solder to the mod pcb later..


(I am not at home again until Monday now.. so will start on the PCB then)

STEP 6

Remove IC900 & R910.

Wire link left pad of R910 to left pad of R914.

5" wire from the above wire link (or left pad of R910). This wire will go to the mod PCB later.

STEP 7

All resistors on the PCB are 0805 33R unless otherwise stated.

The 68R is a regulator 1/8w resistor which solders to the 8MHz mod pad. The free end goes to the long wire which links up the 1772 etc.

8MHz points shown in the image below.

STEP 8

47pF from the 16MHz pad to GND.. There seems to be a lot of under and overshoot on the 16MHz. So the capacitor helps smooth the signal out. I do not believe this is actually necessary for operation, but I do recommend fitting it..

I highlighted in red the link wire between the blitter and CPU wire ( of course this wire should have already been done in the above steps anyway)




STEP 9

Wire 5V and 0V to the PCB.

The support wire is there is something to anchor the PCB down a little bit.




STEP 10

2MHz white wire link..

STEP 11


RED arrows show one wire. From the mod PCB to near the SIL array (GLUE DE from step 1)

The BLUE arrow is the wire which goes under the RAM board (MMU DE from step 2)



STEP 12

32MHz wire (done from step 6)

So off you all go now then! :lol: The race is on...

I think my guide seriously sucks, and I think it looks way more complicated than it actually is :roll:

If anyone needs any more images, or clarifications, then post below and I will take some more images will explain anything any better if needs be....


EDIT:

Due to issues found here https://www.exxosforum.co.uk/forum/viewt ... 941#p22938

Likely the power will have to be cycled a couple of times to get it in a wake up state which works (must leave 10 seconds off before turning back on again).

Holy cheesy nachos Batman!!

exxos wrote: 03 Jun 2019 14:12 So off you all go now then! :lol: The race is on...

I think my guide seriously sucks, and I think it looks way more complicated than it actually is :roll:

If anyone needs any more images, or clarifications, then post below and I will take some more images will explain anything any better if needs be....

Great work exxos.

It is a simple design but to get there takes a lot of wires. It's essentially re-creating new bus lines with wires and circumventing the original lines. I should have my ocd header / jumper wire version working later tonight - fingers crossed.

Only observation I have is be careful soldering to the vias for the DE lines. In moving my board yesterday I caught the wire and it pulled up the track on the top side of the board. Fortunately that track is not needed as we cut it.

Icky wrote: 03 Jun 2019 18:46 It is a simple design but to get there takes a lot of wires. It's essentially re-creating new bus lines with wires and circumventing the original lines. I should have my ocd header / jumper wire version working later tonight - fingers crossed.

Yeah, but even so, its a whole lot easier than the STFM, as the remake has all clock lines going via resistors to allow this mod to be done "easily". On a real STFM.. it be a whole epic of track cutting and patching.

Icky wrote: 03 Jun 2019 18:46 Only observation I have is be careful soldering to the vias for the DE lines. In moving my board yesterday I caught the wire and it pulled up the track on the top side of the board. Fortunately that track is not needed as we cut it.

If your soldering to the top of the pad then yes, the tracks are tiny and can rip off easily. Though I use tiny wire which solders into the via, so its pretty solid really.