[tech] Asteroids graphics fault

[karlcdoe]

Hello all and happy Easter...

Just trying to sort out an annoying graphics fault on my Asteroids and wondering if anyone had any suggestions on what IC(s) to replace?

It's in the X axis and I'm kind-of assuming its a digital fault rather than the AVG circuitry but I could be wrong. I've uploaded a set of pictures to the link below:

http://www25.brinkster.com/pingupgrade/asteroids

Any suggestions welcome.

Cheers

Karl.

 

[P-Man]

You have a bad bit output on your X DAC, this can be one of two things:

- a bad DAC.. to find out, swap it with the one next to it (if you
can) to see if the problem travels.

- a missing DACXx signal, it goes in and out of a 374 before it
reaches the DAC. Get your scope on every pin in and out of the 374,
and measure every input to the DAC, on the dac in case of bad
tracks/sockets. One of them should be bad, if you can identify the bad
one (it will be absent, or look very different to the rest) then we
can go further back if needs be.

I think its more likely to be the latter of the two diagnoses.

--
Andrew Welburn
http://www.andys-arcade.com/

Quoting Karl Doe <karlcdoe@yahoo.co.uk>:

> Hello all and happy Easter...
>
> Just trying to sort out an annoying graphics fault on my
> Asteroids and wondering if anyone had any suggestions on what IC(s)
> to replace?
>
> It's in the X axis and I'm kind-of assuming its a digital
> fault rather than the AVG circuitry but I could be wrong. I've
> uploaded a set of pictures to the link below:
>
> http://www25.brinkster.com/pingupgrade/asteroids
>
>
> Any suggestions welcome.
>
> Cheers
>
> Karl.

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