Video driver thoughts

All information relating to the Alpha plus all the WIP threads etc.
User avatar
sandord
Posts: 678
Joined: Mon Aug 13, 2018 10:08 pm
Location: The Netherlands
Contact:

Re: Video driver thoughts

Post by sandord »

exxos wrote: Wed Nov 28, 2018 5:15 pm Well, you should do which you find best yourself... I would probably suggest coating the pads with solder first, keeping it to a minimum, then flux the pads, then solder the IC.
That went pretty well, for a first time I must say! Luckily, I've been paying a lot of attention to soldering tips lately, confidence is rising :lol:


IMG_20181128_223415.jpg
IMG_20181128_223415.jpg (156.57 KiB) Viewed 3813 times
User avatar
rpineau
Posts: 534
Joined: Thu Aug 17, 2017 6:08 pm
Location: USA
Contact:

Re: Video driver thoughts

Post by rpineau »

Nice job !
Working ones : MegaSTE (68020) / TT030 / Falcon with AB040 & Eclipse / 1040STF
Need testing : Falcon with CT2
User avatar
exxos
Site Admin
Site Admin
Posts: 24081
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Video driver thoughts

Post by exxos »

:bravo:
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
Icky
Site Admin
Site Admin
Posts: 4004
Joined: Sun Sep 03, 2017 10:57 am
Location: UK

Re: Video driver thoughts

Post by Icky »

Eagerly awaiting your outcome sandord.

I have been checking the data sheets, schematic, PCB layout all day and can not see anything obvious. It all looks as expected.

My soldering has been triple, quadruple checked and all looks ok.

Main conundrum is why games like Gold Runner, Magic Pockets work fine but the dark background at boot has small white on the TOS message and purple dark themed desktop.

Looking at the RGB Diag Cart test screen - Left jumper set to 5V, Middle jumper set to GND, Right original circuit (no Video DAC board)
Screenshot 2018-11-28 at 22.14.28.png
Screenshot 2018-11-28 at 22.14.28.png (161.38 KiB) Viewed 3806 times
  • Cyan band has a greenish tinge in the darker part
  • Yellow band has a reddish tinge in the darker part
  • Magenta has a blueish tinge in the darker part
  • White has a greenish tinge in the darker part
At first I was wondering if the RGB bits were mixed up somehow on the board but they are correct.
User avatar
exxos
Site Admin
Site Admin
Posts: 24081
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Video driver thoughts

Post by exxos »

Icky wrote: Wed Nov 28, 2018 10:17 pm At first I was wondering if the RGB bits were mixed up somehow on the board but they are correct.
Did you see my earlier post about trying RGB on a breadboard to see if all is as expected ?
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
Icky
Site Admin
Site Admin
Posts: 4004
Joined: Sun Sep 03, 2017 10:57 am
Location: UK

Re: Video driver thoughts

Post by Icky »

exxos wrote: Wed Nov 28, 2018 10:20 pm
Icky wrote: Wed Nov 28, 2018 10:17 pm At first I was wondering if the RGB bits were mixed up somehow on the board but they are correct.
Did you see my earlier post about trying RGB on a breadboard to see if all is as expected ?
Oh no - I missed that. Looking now.
User avatar
Icky
Site Admin
Site Admin
Posts: 4004
Joined: Sun Sep 03, 2017 10:57 am
Location: UK

Re: Video driver thoughts

Post by Icky »

Icky wrote: Wed Nov 28, 2018 10:21 pm
exxos wrote: Wed Nov 28, 2018 10:20 pm

Did you see my earlier post about trying RGB on a breadboard to see if all is as expected ?
Oh no - I missed that. Looking now.
Don't know how I missed that one. I'll have a look at trying that out.
User avatar
sandord
Posts: 678
Joined: Mon Aug 13, 2018 10:08 pm
Location: The Netherlands
Contact:

Re: Video driver thoughts

Post by sandord »

Icky wrote: Wed Nov 28, 2018 10:17 pm Eagerly awaiting your outcome sandord.
I'm afraid I still haven't finished all fixes so I have yet to power up the board. My biggest fear is that I have fried one or more donor chips, but only time will tell.
User avatar
sandord
Posts: 678
Joined: Mon Aug 13, 2018 10:08 pm
Location: The Netherlands
Contact:

Re: Video driver thoughts

Post by sandord »

Apart from the obvious need to IPA the flux off, I think the caps went well as well.

IMG_20181128_232402.jpg
IMG_20181128_232402.jpg (135.59 KiB) Viewed 3797 times
User avatar
exxos
Site Admin
Site Admin
Posts: 24081
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Video driver thoughts

Post by exxos »

Icky wrote: Wed Nov 28, 2018 10:24 pm Don't know how I missed that one. I'll have a look at trying that out.
I think with a binary input, you should see voltage steps like this on the output (before the big cap on the video board)

1.jpg
1.jpg (27.71 KiB) Viewed 3797 times
So try RED inputs first, 0000 should give for example 1.787V output, and 1111 should give 3.178V... probably about 0.1V per step.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Post Reply

Return to “ALPHA DEVELOPMENT INFO”