exxos's Atari, Amiga & retro forum

exxos wrote: 28 Nov 2018 17:15 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:

Nice job !

:bravo:

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)

• 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.

Icky wrote: 28 Nov 2018 22:17 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 ?

exxos wrote: 28 Nov 2018 22:20

Icky wrote: 28 Nov 2018 22:17 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.

Icky wrote: 28 Nov 2018 22:21

exxos wrote: 28 Nov 2018 22:20

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.

Icky wrote: 28 Nov 2018 22:17 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.

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

Icky wrote: 28 Nov 2018 22:24 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)

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.