Blue/red speckled problems flickerfixer on A3000

[Overmann]

Hi there,

I'm just wondering if anyone has any thoughts on where to start to fix my graphical distortion.

I just got my first ever A3000 in the mail and while the machine works it has a couple of issues. Most noticable is the graphical problems when using the flickerfixer. High Res Interlaced get's this kind of distortion:

https://imgur.com/yr0INut

I've tried tuning the little knob by the 15pin port with a screwdriver, but it does nothing that effects this. I've seen much more severe, and different, disrtion being caused by faulty FRAM and PAL's. Is that what I'm seeing here as well, or could this be something else?

dblPAL looks fine except for some distortion at the very top of the screen:

https://imgur.com/2yQvZZm

[matt3k]

My first guess would be a flakey denise, especially if the battery leaked. Check the legs on denise and look for green corrosion. If you thoroughly clean the socket and chip, you may get lucky although doubtful. Try swapping another denise to see if that fixes it.

You could try adjusting the blue video pot on the mb.

My advice is pick up one of the new 3000D motherboard offerings and start fresh.

[Overmann]

Originally Posted by matt3k

My first guess would be a flakey denise, especially if the battery leaked. Check the legs on denise and look for green corrosion. If you thoroughly clean the socket and chip, you may get lucky although doubtful. Try swapping another denise to see if that fixes it.

You could try adjusting the blue video pot on the mb.

My advice is pick up one of the new 3000D motherboard offerings and start fresh.

Buy a new PCB, and build a brand new motherboard? That sound extremely difficult/expensive..

[matt3k]

Originally Posted by Overmann

Buy a new PCB, and build a brand new motherboard? That sound extremely difficult/expensive..

Agreed, it would be pricey.

For now just look for green on the legs and slot, and try another denise.

Sadly original systems seem to be failing these days as they were never engineered to last this long. So that is why a new build is tempting. In the end you send a system out to repair and chase gremlins, where if you would have just started fresh it may have been a better path.

Good luck!

[Stedy]

Hi,

Check the solder joints around the flicker fixer VRAM devices, U470-U475 and U479.

Looking at the pattern, you've got a faulty address pin, one one of the sets of RAM as the disturbance in the video is at regular intervals.