Nancy Drew and the case of the missing W2 link

[towmater]

 I was going to add the jumper to make the external STF Rev C. floppy to boot as drive zero, but that circuit board trace seems nowhere to be found. Does anyone have experience or can suggest an alternative?

 

Edited April 9, 2020 by towmater

[ParanoidLittleMan]

To work it properly you need to swap lines Drive 0 and Drive 1 (select lines).  They start at PSG chip:  pin 19 is drive 1 and 20 is drive 0 .

So, single jumper will be not enough. If can not find circuit layout for your concrete board revision need to trace lines with ohmmeter, using schematic - what can find online for sure. 

And easiest, for some tastes maybe not so good solution would be to cut those 2 pins of PSG chip near to board and put there something with what can swap those 2 lines - what can be 2x alternate switch for instance, what can mount in ST case, so will be accessible from outside.

 

[Umberto]

As stated above on a STF its the Yamaha 2149 (U19) pins 19 and 20

 

https://rdemming.home.xs4all.nl/Atari/DriveSwapAtariST/

 

 

Edited April 10, 2020 by Umberto

[towmater]

3 hours ago, Umberto said:

As stated above on a STF its the Yamaha 2149 (U19) pins 19 and 20

So where it says "drive select A on the motherboard" it's just wherever pin 20 was going before I bend it up and out of the socket?

 

[Umberto]

7 hours ago, towmater said:

So where it says "drive select A on the motherboard" it's just wherever pin 20 was going before I bend it up and out of the socket?

 

Yes

Edited April 11, 2020 by Umberto