exxos's Atari, Amiga & retro forum

Got my STF mostly fixed, got to do the DMA floppy problem still but it boots to desktop every time now.

What are the settings for jumpers 1 - 3.

Mine boots great into high res with the DAC fitted but is black screen in all other modes using the UBE.

Forgottenmyname wrote: 29 Nov 2018 13:26 What are the settings for jumpers 1 - 3.

https://www.exxosforum.co.uk/forum/viewt ... 1185#p9679

that took me to the STF jumpers, I meant on the video board.

exxos wrote: 29 Nov 2018 13:18 So my small PSU has gone wonky again.. so back to my mega psu..

IMG_3600.JPG


I tried the RED channel..

R2, R1, R0
000 = 1.68v
001 = 1.89v
010 = 2.10v
011 = 2.30v
100 = 2.51v
101 = 2.71v
110 = 2.92v
111 = 3.12v

So looks like 200mV each step.. which I assume is correct...

Interesting. Is it the same for Blue and Green. I tried Blue.

Looking more likely I have BAD DAC may be.

Icky wrote: 29 Nov 2018 13:38
Interesting. Is it the same for Blue and Green. I tried Blue.

Looking more likely I have BAD DAC may be.

I've not tried the other chans, just made room to setup the STF again and see what happens...

My first power up the bit planes were shifted... :shrug:



But it looks like I have the same problem as you Icky ...



The odd thing is as the colours change in the Atari logo, the purple background gets cleared away back to white then gets washed back into purple, then white again...

Really am confused.... :stars: :stars: :stars: :stars:

exxos wrote: 29 Nov 2018 14:15 The odd thing is as the colours change in the Atari logo, the purple background gets cleared away back to white then gets washed back into purple, then white again...

It's almost as if the DAC board causes some kind of feedback into the shifter-glue path. I mean, how else could colours on a certain part of the screen influence those in another part? The DAC doesn't have a frame buffer so somewhere else something must be crossing over...

sandord wrote: 29 Nov 2018 14:19 It's almost as if the DAC board causes some kind of feedback into the shifter-glue path. I mean, how else could colours on a certain part of the screen influence those in another part? The DAC doesn't have a frame buffer so somewhere else something must be crossing over...

I have no idea... Maybe the digital lines need series resistors in them or something..

I think that this observation is interesting: the problem appears to happen only vertically, horizontally the colours are often wrong but consistent. Just as if the palette changes per line...