Ok. Ofter looking at the datasheet for the 7805 regulator, I can measure 4.95v at the output and 11.9v at the input. I was probing the wrong leads before. I can't get a voltage across anything else,though. I'm going to flow a bit more solder in the regulator leads and see what that does. I also noticed that the wire coming from the output lead of the regulator does not seem to be connected to anything. There are two holes in it for component mounting, but there are not components there. As soon as I find my good digital camera, I will post a picture of what I am talking about.
edit:Ok,here's the picture. The output of the regulator is in the bottom right. There is one big green line going from it, and then two holes with nothing in them. I'm not sure if something is supposed to go there, the manual does not mention anything. If anyone else has a zx81 and could post pictures of the same area, that could be helpful.
Picture
Update: I probed it a bit more, using the ground of the regulator as a reference for the voltage. I am detecting 3-4v throughout different parts of the pcb, I have been able to get a voltage on a least one pin of every ic socket, so the pcb is getting power throughout, at least in some parts. I'm thinking it's either me not knowing how to tune the tv or I wired the rf modulator. I've got an old tv circa 1987 that I'm going to try. The instructions indicate that I should be getting a signal on channels 30-40. I don't think it's like a timex 1000 where the tuning is done to channel 2 or 3. I believe the jumper wire just selects 60hz. If anyone has any additional info, that would be appreciated. I wish I had a scope to see if I'm getting output.
Update 2: When I plug in the zx81, the picture on the old tv goes from solid white static to a rolling/wav pattern, so I think some sort of signal is being produced. However, I cannot see any hint of a k prompt.
Update 3: Possibly more good news. My multimeter can measure frequency. When I put it in the video port, I get a solid 60hz measurement. So, at this point it would appear that the computer is possibly functioning ok. however, I still can't seem to get a picture. If it was outputting a pal signal, should I stilll be able to see a k prompt?
Update 4: Ok,I discovered that I had managed to solder the rf output in the wrong spot. I redid it to the correct spot, but I still don't get a picture. However, the ULA gets hot after only 30 sec or so of running..is my ULA shot? That would explain why I'm getting no video signal.
Final update: The person I bought the kit from sent me a new ULA free of charge as they have experienced a failure with about 5% of the kit ULAs. I received it today and swapped it out with my old one. I now own a working ZX81!