Dingdong Pong Throng

Again, eBay is weird. After watching the price of EVERYTHING that is retro gaming or retro computing related absolutely sky-rocket, I still managed to bag a 70's pong clone for four quid.

To be fair, the seller advertised it as 'non-working' and that they'd tried to make it work and it did sort of work but then it decided it wasn't going to work so he wasn't going to spend any more time on it. His loss.

So we have a PrinzTronic Tournament IV something or other. It's a fairly generic pong clone from c.1977 produced for Dixons (a UK high street electrical retailer which is no longer on the high street but Dixons Group owns Currys and the soon to be re-named Carphone Warehouse). It's very silver. And very, very dirty.

Silvery Seventies

Time to get that top off.

There's not much in here...

It's powered by the TI TM1965 pong-on-a-chip chip which is pin compatible with the AY-3-8500 from General Instruments. The bulk of this unit is all the option switches and the game selection switch. And a TV modulator with attached RF cable. RF. Urgh.

The brains of the operation

The power socket is a standard 3.5mm socket which I would normally expect to see as a headphone or mic socket. But it's not out of place in a console of this age and type (looking at you Atari Jr). It's also got quite a bit of corrosion on it from a previously abandoned set of batteries. 

It's not easy being green...

Fortunately, none of this corrosion has made it to the main board. But there is a slight, minor, tiny little issue with the main board. It's got several, what might be described as, hoofin' great cracks in it. Oh dear. This may explain why the previous owner could not get it to work correctly.

Purple arrow - crack in the board
Red arrow - broken solder joint

This is Not Good(R).

So first things first, let's try to get the game selector switch off without causing any more damage. The de-solder station made light work of this and left all the pads in place (almost) which was good. Being from the 70's this is clearly constructed with proper, leaded solder. None of that ridiculous 'lead-free' nonsense here.

Get out o' there!

Next, try to fix the board. The repair here is only intended to try and keep the circuits correctly connected. The cracks are there forever, but I soldered a large pin across the ground plane to try and reduce the stress on the board once it's screwed back into the case. 

Can we fix it? Of course.

One pad did make a (successful) break for freedom and this required the installation of a bodge wire from the appropriate pin of the switch. The rest of the pins should give enough mechanical strength to hold the switch in.

Now this is done, time to test. For that, I needed two things, power and a TV output. I know that this needs 9v since it would have used six 1.5v 'C' batteries. All I had to work out whether the power socket was centre negative, or centre positive. Using my multimeter I checked which terminal on the power socket had continuity to the ground plane and confirmed that it was 'centre negative' just like the Speccy.

For TV, I had to plug it in via RF (urgh), for which I used the 6 inch Sony Trinitron. This was exciting as I had not had to tune it in before, but I managed without having to refer to the manual...

Is this a dagger I see before me? No, it's a telly.

Well, that works then. Note that the bats are missing as I had de-soldered the controllers (such as they are) to allow for easier working on the board. Now I knew it was working, the next job was to improve the picture. This unit has a TV modulator which means that one of the inputs into it is likely to be a composite signal. After a bit of trial and error (mostly error) I worked out which input to the modulator to cut, and which to connect directly to the centre pin of the modulator output. The results are mighty impressive (well, to me anyway) and a vast improvement over RF.

That's better!

Simple composite mod.

So, time to get it all back together. This required me to solder the cables for the 'controllers' back onto the board, juggle all of the cables for said controllers and then feel that I really needed three arms to get everything back into the right place. And then I hit a couple of problems.

1) The right bat would not appear on screen

2) The picture would go weird if anything so much as brushed against the game selector switch.

First job, clean the potentiometer that is the controller. This just needed me to open the case and spray a bit of contact cleaner into the body of the pot and then give it a damn good wiggling backwards and forwards. And this worked - once I soldered the controller back on to the board it re-appeared straight away. I did the same on the other one too since the bat was very jittery on screen. A good spray and wiggle sorted that out too.

Not a lot in these controllers.
DualShock4s they are not.

Next was the game switch problem. I took the board out of the case again and inspected the bottom. I couldn't be sure but it looked as if the solder blobs I had added to the board had broken along the line of the original cracks. Fortunately, the cracks zig zagged across just one track (from the ground plane) so I added another bodge wire.

New bodge wire.

Finally, I cleaned the selector switch in the same way as the controller pots. Spray and a good hard wiggle.

So, second attempt at re-assembly and I, again, wished I had three arms. But I got it back together without the top case and tried it again. This time, both bats appeared and were rock solid, and the game selector switch generated no interference. Every click firmly switched between the game modes with no glitches or stuttering. 

Nice.

After a good clean I re-installed the top case. I should also point out that this machine had a socket on the back for connecting a light gun. I removed this as it is never going to be used - the only CRT I have is the 6 inch Sony - and had already been disconnected from the board anyway. I can live with that.

Another 70's console saved from the e-waste bin. BEEP! BEEP!  BEEP BEEP!