Damaged DE-10, would like advice on finding and fixing damage

[toastboy]

I damaged my DE-10 by using the analogue 15khz output to test an arcade cabinet CRT+cabling that was not really ready to be tested.
Seems like a short on the VGA pins caused some minor damage to the DE-10.

The result is not a spectacular fail - it's caused a pattern of green artefacts on the HDMI output and slight banded interference on the IO board output.

I suspect the short has fried some component between the DE-10 and GPIO that's intended to defeat interference, and without it there's noise now.

I've got access to all the tools required to fix this - hot-air smd gun, good multimeter etc, but need some pointers on what to test for, before I get nasty on such a delicate board.

The CRT meanwhile is fixed, working great in an old Golden Tee cabinet, and running Mame until I can get the DE-10 Working right.

[caad]

Best case you can find some fried SMD component like a resistor or diode near the VGA port.

[toastboy]

Tested without the IO board and USB hub - interference is still present on HDMI out, so it's definitely the DE-10.
A fried diode or resistor would make sense tho - voltage now passing where previously it could not, hence the interference.

[toastboy]

Had an idea.

So far I've been testing the analogue output on a 14" TV with VGA to SCART, where the banded interference is pretty obvious, and via HDMI where the green speckles appear.

Instead retested on the arcade cabinet's Hantarex Polo2 CRT again, using VGA to HVRGB connector.
For whatever reason, the interference is not visible on that screen.

I'm not sure if it's the big chunky nature of the components in the CRT, or possibly the separate HV sync on that monitor, but there's no visible interference at all.

So there's a new plan. The fried DE-10 goes in the arcade cab, it works perfectly well in there.
I'll rebuild my desktop mister around a new DE-10 - I'd already grabbed one to use in the arcade cab anyway.

[held]

If you fried one of the components, why not measure components one by one. You should, if your theory is correct, find one that shorts. (smell the board, that would give you an indicator too where to start)

You could also watch some Adrian's Digital Basement, he restores a lot of stuff. And since he describes exactly what he's doing and why, this should be a gold mine of pointers.

[C-R-T]

It’s probably not fixable.

But try direct video and see what it looks like.