Pong! What more could a young child want in 1978? Despite my formative years, I was already hooked on my friend’s magic-filled box of delights he described as a ‘TV Game’ (for ‘console’ was a word of the future). We would Pong, Pong and Pong some more. Then, in a rare moment of wish-fulfilment for a working-class lad from Liverpool, Santa brought me my very own TV Game, a Binatone no less!
Ah yes, Binatone, that stalwart of the “well, it does the job but it’s nothing special” area of the electronics market. Binatone, like many of its contemporaries, had bought into the AY-3-8500 integrated circuit. This little beauty from GI packed a handful of Pong-a-likes onto a single chip that handled input, switches and all video and audio output. Just a stick a few basic components around it to make sure it behaves itself and boom, you have a games console. Yes, 1977 and GI already had SoC nailed. This led to an avalanche of over 200 near-identical looking products that all played the exact same games.
I loved my Binatone and played it for hours, happily destroying my social life and any incidental exercise it may have brought me. Still, times move on and soon I was basking in the glory that was the flickery screen of my ZX81, my poor old Binatone left in the cupboard. One day, Dad took it to the farm so it could live out its days grazing in a sunlit field. At least I think that’s what he said.
Anyway, nostalgia got the better of me a few weeks ago and I located a lost and lonely TV Master Mark IV (for that was its model name – despite the fact there was never a Mark I, II or III) for the princely sum of 99p. Delightfully, following a clean-up, it sprang to life and challenged me to a game or forty.
There was only one problem, the picture. As I spend a frankly irresponsible amount of time cleaning up and repairing old computers, I have a couple of old CRTs that don’t mind creaky old signals from the 20th century. This allowed me to confirm that it was indeed working, but the analogue tuner on my usual LCD TV was barely able to lock on to the signal and if it did it looked terrible.
This would not do.
A lot of Internet searching later and to my surprise I found you could modify most AY-3-8500-based consoles to provide a composite output. This took a lot of looking around and experimentation, so I thought I would take the time to write up the procedure here. Best of all, you can perform this mod without disabling the RF output, so if you want to ‘keep it real’, you can.
- You know which end of a soldering iron to hold
- You won’t blame me for anything
- 1 x 9V – 5V Voltage Regulator (7805)
- 2 x Resistor – 75 ohms (metal film resistors preferred)
- 1 x Resistor – 750 ohms
- 1 x Transistor 2N3904 (or comparable)
- 1 x Low voltage diode 1N914 (or comparable)
- 1 x 100uF Electrolytic Capacitor / 16V
You’ll need some wires, stripboard and (if you like) phono connectors as well.
The AY-3-5800 works by generating three TV signals: The ‘field of play and scoreboard’ and the left and right bats. These need to be combined to produce the final signal. You also get a ‘sync’ pulse from one of the pins that the composite signal will need.
So, we’re interested in Pins 6, 9, 10 & 24 for the screen, 16 for the sync and 3 for the sound.
We’ll find a point on the board where the signals are combined and tap off it. Also, we can get a feed from the 9V power and ground. However, as composite standard is 5V, we’ll need to step down the voltage accordingly. We can also get the audio output from the unit (it normally uses a built-in speaker) and create outputs for that as well.
Using your impressive stripboarding and soldering skills, create this circuit, designed by Manuel van Dyck:
I identified a point where all the signals were combined and took a line from that. I also took a line from the ‘sync’ pin.
A quick test showed a great (if slightly dim) composite signal. Time to do it properly. After an audio test, I got the drill out (gulp). I also took the opportunity to cut short the built-in coaxial cable and replace it with a phono plug in the front.
Carefully installing the stripboard, I soldered the phono plugs in (which was a real pain) and reassembled the unit. Audio requires nothing special, just connection to a phono plug and the ground.
My lovely little Binatone TV Master Mark IV has a new lease of life with a rock solid video picture (well, it’s no 4K but you get my meaning) and audio through the TV speakers as well. This will guarantee its operation for the foreseeable future as even upscaling to HDMI is trivial. Not bad for 1977’s finest.
Circuitry aside, it’s interesting that its analogue nature means the responsiveness of the games is amazing. Still very, very playable all these years later.
Inspiration (and good cold hard data) for this mod came from:
My thanks to them both.