TylerEss said:

Dana, I adore your loving photography of these old Macs. Grats on getting 'er out of the closet and running!

What do you reckon is the cause of the flickering green channel?

My Mystic's red channel does that sometimes. A quick lookover of the analogue board revealed nothing, so I'm afraid the electron gun is just getting lazy. I'd love to hear a more-hopeful theory!

Click to expand...

Ta! The flickering green was a cracked pad-trace point on the video amplifier. I tested continuity over traces that should be connected, and while the traces were fine the solder blobs didn't contact. I added a wire to manually connect the pins and all was well.

https://dl.dropboxusercontent.com/s/rzgqfat0z3kk2bi/Q1rpu0h.jpg?dl=0has the amplifier IC labeled in red near the bottom. It was one of the joints underneath it. Nothing remotely *looked* dry or cracked of course!