So I decided to rescue two Elks picked up from ebay and gumtree some time ago.
The first one was pretty straight forward with the usual dodgy RAM and a few dry joints here and there.
The other is a whole different ballgame. My god she's had a hard life!
It would appear that the last person to open her up decided a sledge hammer and chisel was far more efficient than a soldering iron. I've attached a pic of some of the (missing) CPU vias. Thankfully the vias don't appear to go anywhere on the underside so hopefully it will be straightforward. I have a Rockwell on order as a replacement but these will need repairing first. The picture below is just a snapshot from my microscope. Once I have a full compliment of IC's, I'll fire up the oscilloscope and get to work on her.
The board is in tatters but I'm determined she'll live again
I've also noticed that LK2 seems to be set to NTSC (top two pads bridged)? Is that correct? The service manual I have says the bottom pad (south) should be bridged for PAL. Am I reading it wrong?
Elk from the ashes
Re: Elk from the ashes
For PAL, LK2 should be bridged so that it connects IC12 (74LS74) with IC14 (74LS86), as opposed to connecting IC14 with 0V. At least according to the Electron Advanced User Guide and the circuit diagram I converted to KiCad.