Phoenix Freeplay and Scramble High Score Save Kit

This week I mustered up the courage to try replacing chips on game boards and soldering sockets. This was fairly new territory for me, but I’ve been watching Tim work (as well as many Youtube videos) and taking notes, so it was time to take the leap. I started small and easy with simply replacing a couple of ROMs on my Phoenix PCB game board to add the freeplay functionality thanks to Jeff’s Romhack.

ROM 48 replacement on Phoenix PCB

I have to admit this was fairly easy, I just had to carefully remove two socketed ROMs numbered 45 and 48, and then be sure to replace them with the modified ROMs making sure the notch was aligned the right way.

Align notches of replacement chips to ensure they are all facing the same way

One of the things you figure out (which is useful info) is these chips are stronger than you think, and they can take a bit of push and pull. That said, the fear of breaking off a leg is real. I did have to pull chip 48 back out gain given one of the legs did not align, but other than that it was quite painless given there was no soldering required, just pull out the old chips and insert the new ones.

ROM 45 replacement on Phoenix PCB

So with the Phoenix free play ROMs in, I was ready to return to the last bit for my Scramble restore, namely installing the high score save kit with free play I ordered this summer. This should have been simple like the Phoenix ROMs swap, but the snag with this one was the 40-pin Z80 processor on the Scramble board was soldered in and I couldn’t simply pop it out. I needed to desolder it, and then solder in a socket that the high score save kit could plug into. Trick was I needed to make sure the Z80 chip came out cleanly cause that was going to be seated in the mod chip set for the high score save kit.

My first desoldering and re-soldering job on a 40-pin Z80 socket. Not pretty, but it worked.

So I was a bit nervous, but I decided to bite the bullet yesterday and desolder the pins for the Z80 processor, which was a royal pain in the ass. It wouldn’t come out cleanly, and I was afraid to break it with too much force. I must have desoldered the pins five times. Eventually I got the chip out relatively clean and was able to solder in the socket:

Soldered 40-pin socket, you can see the signs of me trying to remove the z80 chip on the board 🙂

It felt pretty good to get this far, but now I had to seat the Z80 chip into the high score save kit, and then plug that into the socket:

Scramble High Score Save Kit Z80 chip plugged into mod kit

So the Z80 went in cleanly, and you can see on the other side of the high score save kit there is a 40 pin that sits in the socket I soldered:

Underside of high score save kit

With all that done, I was now ready to test the board. Moment of truth, and on the first go I got garbage on the monitor, and amongst the scrambled graphics I saw the term PLOOOP. I thought that might help with a search for a fix, but I got nothing. So I went back over the pins I soldered and turns out I missed one (I could tell because it was loose), so I re-soldered it and tried again. Not feeling all that optimistic I re-connected the PCB and BAM—the high score save kit was working!

Freeplay working in Scramble

High Scores saving in Scramble

This may have been the most rewarding arcade project yet, simply because I never thought it would work. If you would have told me I’d be desoldering and re-soldering 40-year old arcade circuit boards I would have laughed. But if you will it, it is no dream!