Thought I'd post a few pictures to show that the F18A can indeed be fitted neatly into the console:
This first pic shows the F18A VGA connector fitted into the case of the console. It is necessary to remove the steel support from the VGA connector that is supplied with the F18A, and also the black plastic shroud around the VGA connector pins. Use a sharp knife to cut away the plastic to make a snug fit, then drill two holes for the VGA connector screws to hold the connector in place on the case. De-solder the original analogue video out connector from the mother board. You can also see the cartridge cover has been removed to expose the grille in the top of the console. A 45mm Mylar speaker fits just great. Use two little spots of Uhu glue to glue it in place:
This picture shows the VGA connector in-situ. Note that the UPPER case is cut and drilled, not lower case!
Make sure to use washers and a split washer to hold the nut tight; it's a pain in the ass when they come loose and you have to open the console up to tighten them again:
Cartridge cover back in place. Solder the cables to the speaker before you put the cover back on!
I took the power supply for the internal amplifier (a kit from Velleman) from the mother board. As can be seen, I've tapped into the +12V supply:
Here's the F18A taking pride of place. Obviously the 9929 has been removed! Take care to fold the video cable so that it exits towards the back of the circuit board.
Re-assembling the motherboard case. The F18A fits inside the steel case just fine. You can see the amplifier, which as yet to be stuck down. It's very small, measuring about 35mm by 45mm.
The amplifier is stuck to the 'roof' of the console, just to the side of the joystick port. It fits in there just perfect, the steel case on the mother board doesn't foul it!
All re-assembled - all fits together just fine!
The VGA connector looks quite neat and is the only clue that something different lurks within!
Oh, and the speaker! If you have some thin black plastic anti-static gauze (the type that is supplied with ICs sometimes) then you put that between the grille and the speaker to cover the speaker up.
The final test: Beautiful crisp display on my 1024x768 LCD VGA monitor:
The amplifier works fine too, and is as loud as hell! It's rather noisy though; there is an awful lot of noise picked up - you can 'hear' the 9900 processing. Of course, speech also comes from the internal speaker now, too. I'm going to add a rotary volume control to the side of the console next.
I took the audio output from the original audio out at the video connector. I understand that at this point, the audio signal has already been amplified a little for sending on to the UHF modulator. I'm open to suggestions as to alternative locations that I could pick up the audio signal from (somewhere less "noisy" I hope). Maybe I can just connect directly to the audio out pin on the sound chip?
My next little project is to add a two-stage flip-flop to the clock input on the sound chip to drop the sound by two octaves to give proper bass notes, giving a much more usable audio range.