Truxton II Graphics Issue (Resolved)

[quarkstarmuffin]

I have a Truxton II board that's exhibiting graphics glitches and constant sprite flickering.

I booted it up in test mode and the RAM and ROM checks look good. No visible damage on the board but there's evidence that the chip at position U30 was previously soldered.

Packaging on the board was very thin so I wonder if there's something that could have been damaged during shipping that might not be immediately evident from a visual inspection. I heard the hk-1000 chip is fragile and prone to issues but as I understand it that seems to mostly deal with input logic, and it doesn't obviously seem like it would be related to this.

Any thoughts on what could potentially cause this type of issue or what else I should check?

 

[nnap]

I had a Fixeight that had some sprite/colour issues with a cracked hk-1000. replacing it also fixed the graphics glitches but that might just have been luck.

 

[ShootTheCore]

Agree that you should check the hk-1000 custom for cracks - @caius sells reproductions if you need one.

It's also common for the large SMD custom sprite generator chips on those boards to come loose. Carefully reflow the solder joints on it and see if that helps.

 

[caius]

Check the GP9001 ASIC and eventually reflow it.Check also the dynamic RAMs connected to it, they often fail.

 

[quarkstarmuffin]

Ok, so I found that if I push down on the GP9001 ASIC in just the right way it seems to fix the graphics so it seems like reflowing that will probably do the trick. I've never done this for an SMD chip though. . .what would be the best way to reflow it?

 

[rewrite]

I've never done this for an SMD chip though.

Find a friend who has done it. Or pay someone who does it professionally.

 

[ShootTheCore]

Find a friend who has done it. Or pay someone who does it professionally.

^ this. You don’t want to attempt this yourself without a temperature controlled soldering iron, a small tip, plenty of flux and magnification.

 

[quarkstarmuffin]

^ this. You don’t want to attempt this yourself without a temperature controlled soldering iron, a small tip, plenty of flux and magnification.

All of which I do have, but I definitely wouldn’t want to put a soldering iron anywhere near that smd without plenty of practice on inexpensive chips first.

What I did feel confident in trying though was using a hot air gun to just reflow the existing solder and fortunately that was enough to get it working

 

[ShootTheCore]

Glad it’s fixed!