A3000 Scan Doubler problem.

[x56h34]

I wasn't happy with the display quality of the A3000 scan doubler output to my VGA monitor (picture was jumpy on 640x400) and I've decided to fine-tune it by rotating the little tuning screw a bit with a screwdriver (the hole next to the VGA port in the back of A3000) and to my misfortune the screen is now royaly #%*$!! up. I just touched it a little, that's all, and I can't get any normal display anymore, just garbage on screen. I've tried to tune it back but it just won't work anymore. What happened here? How do I fix it?


Thanks.

[x56h34]

Well it seems that the screw is turning. I have a small screwdriver that fits ok. I pointed a flash-light towards the hole so that I could see what's happening and I saw the screw turn alright.

I was really gentle while tuning, too. Can't believe that I damaged something by force, or similar.

[x56h34]

I've just learned that A3000 came with a plastic screwdriver for the VGA tuner. I was tuning mine with a standard metal one. Perhaps that's why the display always gets corrupted as something non-conductive must touch it. Should I try looking for a plastic one?

[x56h34]

I figured that it could be that the pot was simply too old and once I moveid it from the default position, it died. Upon closer inspection, the screw looks rusty too. Good thing that it can be replaced though. ;-)

I guess I'll play around with it a little more and if I fail to get any results I'll simply buy a new pot and replace it.


Thanks for your help. Much appreciated.

[x56h34]

Thanks dude. I am though 90% sure that the pot itself is damaged. The display is simply terrible. There is no picture at all, just interference. If I am lucky, I can tune it back to 40% usable picture, but it's still garbage. The display looks like those locked out cable TV channels.

I'll try and look for a pot which fits nicely and is of higher quality.

[x56h34]

OK, I am now positive on what is wrong. The pot is damaged. If I try to move the whole pot box as right as it can go without breaking it off from the motherboard, the picture magically comes back. As soon as I touch the screw with a screwdriver, the pot moves and loses contact with the motherboard and I get crappy picture again. In conclusion, it seems that I need to either get a new pot or possibly fix the solder points on the old one. It's possibly best to try and get a replacement which would work but would sit in there firmly.

[x56h34]

@shaf:

Thanks for your suggestions. I usually shop for these kind of parts in the Steeles/Victoria Park area. There are a bunch of stores there that sell components, and it's closer to where I live.

[x56h34]

Shaf,

The only source of Amiga hardware left in Canada are individuals like you and me. There is one active dealer that I know of, which is LiveWireSystems, however their stock is rather limited (only Amiga One and Elbox offerings...nothing like accelerators, or rare/fancy stuff).

BTW, are you still able to repair Amigas? Maybe you could fix this scan-doubler pot trouble for me? I have a friend who usually does these kind of repairs for me, but he's been rather busy lately and hard to get ahold of. I know how to solder and all, but only basic connections. I wouldn't dare touch a motherboard yet with my Walmart Soldering Iron (if you get my drift). :-)

[x56h34]

shaf,

This can certainly wait. I'm in no rush. Let me know when you are ready, if you're interested that is.

[x56h34]

@voxel:

Thanks for your suggestion. There's no doubt that this A3000's pot has bad solder connections underneath it, but I was thinking since I will be taking the whole unit apart maybe it would be smart to look for a better pot altogether. One with a knob which would stick out through the screw hole and be reachable outside of the case. Worst case scenario, I'll fix the solder connections and keep the original pot. :-)

[x56h34]

Thanks Voxel! I will try and fix the solder joints and see what happens.