A1200 Wrong Colors

[FOL]

Well it was working before, so something you have has caused.
Retrace your steps checking all print to make none are damaged.

Is it the same on all outputs?

[Retrofan]

It is light blue with Comp.

EDIT: UUUF! I've given her an Isopropylic alcohol "bath"*, better than mines... , and it's working again... ... but just like before

Surely it had too much soldering paste and it must be conductive ?¿

It seems this board as I was thinking will take it's way to UK... but before I will wait for other leds to try the Anemos' Revenge, Lol.

*With a brush, of course.

[Retrofan]

Yesterday I tried the "Anemos' Revenge" (post 21) with different leds, but it doesn't work and they don't show any light.

Today I've changed these:

Originally Posted by Zetr0

...
Each Analog R.G and B component have a subtle +VIO pull ups before their output to the video port. each component of the R, G and B are Pulled up using a 1N914 Diode these are labled

D231A
D232A
D233A

of course there are VIO regulation Diodes as well for the Video Ground -VIO (again 1N914)

D231B
D232B
D233B

And also tried these (well, I changed all the electrolytic caps some weeks ago):

Originally Posted by Zetr0

...
Firstly we must ensure that the right voltages are correctly processed so the following list are capacitors responsible for filtering of specific voltages for the Amiga

Power Filter

Mono Ceramic

IDent. Value 

C801 0.1uf (+5v )
C802 .01uf (+12v)
c803 .01uf (-12v)
C804 .22uf (+5v )

Electrolytic

IDent. Value

C811 1000uf (+5v )
C821 47uf (+12v)
C822 47uf (-12v)

Now I was searching for this part:

Originally Posted by Zetr0

...

Thats an a lot to look at, for me I would pay most attention to the Video Decouping and the VREF pull ups C215 and C217

I've found C215 or C216, but I haven't found C217.

Where is it, please?

BTW I forgot to say that using Comp I get a flashing screen changing different colors (Edit: but that's just because of using NTSC now; with PAL it's like before). Using Video output (Amigakit scart) I see it normally with wrong colors, like always.

Edit: C215 changed. I don't see C217. Won't it be C30A, beside R217?
Edit: C30A changed. Did I say I don't find C217?

[rkauer]

Did you look in the other side of the board?

[Retrofan]

Originally Posted by rkauer

Did you look in the other side of the board?

Yep . I think I will have to use the Indi with this mobo if I can't fix it.

[gibs]

[Retrofan]

Originally Posted by gibs

... Today I've received a PM:

Originally Posted by Romps

Hi i have been searching for weeks on a fix for wrong colours on a1200

And came across your post many times on my search
I have seem to have fixed mine by removing the D125 chip and using the LED and 1uf cap on D125A
The colours are now really bright and vivid

Hope this may help you in fixing your colour problem


Regards
Romps

Ok, first I've just changed my D125 chip with a donnor, but it was more or less the same (well, now with Comp the screen wasn't flashing different colors, but the color was wrong), and the "Anemos' Revenge" trick, never has worked here and I had no light on the led.
Then Romps has confirmed that he didn't put another chip, as he hadn't, he just taked it off, and he told me that to have light on the led, the chip has to be off.

Originally Posted by Romps

You have to remove the chip for the led to light up as the chip is just a zenor diode anyways

i didnt have a new chip to try so i just removed it

IT WORKS NOW! No D125 chip and just a led (I have to search for the cap), and now the led turns on and the colors seem to be right...

Thanks Romps

[1time]

Really great to hear that you have fixed the problem. Maybe you could edit your first post with the solution?

[Retrofan]

Thanks, but I don't think this is a magical remedy. If any of the chips I've changed would have been wrong I would have fixed it before, so better to read all the thread for all the possibilities. And really the fix is already posted, it's the Anemos' trick, but without the chip D125. http://eab.abime.net/showthread.php?t=43207

[gibs]

Great to hear Solder Junky !!!

[Retrofan]

Lol thanks, great that now we are 2 to make a Club...

[TjLaZer]

Originally Posted by Zetr0

@retrofan,

Sadly my friend the fault you are having is a Bad (dying) DAC (Digital.Analog.Converter) its very common on the 1D1 board I have 3 of them that have suffered this fate in a box awaiting the day I can find the right revision of DAC.

There are 3 different DAC revisions used in the A1200, each with a subtle modification specific to the motherboard revision - I have a repaired one, but it has tearing on one side of the screen - as its not the right version for the board.

btw, U30 is the DAC =)

Sorry I wasn't here sooner to help.


Interestingly enough - any clip-on SCAN Doubler has its own DAC and by-passes this problem.

I have a 1D1 board and just developed a fault with the video, pink bright screen and some screen flashing. The DAC is hot to the touch. Sounds like what you described.