Thursday, February 07, 2019

Replace the word 'Song' with 'Pong' in any film title...

Some classics there. The controversial 'Pong of the South', the obscure 'My Pong goes Around the World' or the immortal 'The Pong Remains the Same' from Led Zeppelin.


The old Interstate console has been sat waiting patiently for some attention. Well, the donor Interstate machine has now arrived and, despite being in great condition, will soon be giving up its parts for the collective good. Comrade.

And kudos to the eBay seller who provided the best packaging I think I've seen from anyone on eBay.

Great Packaging

Super Clean Donor Unit

My console works without any issue other than the joystick and so the first thing to do is remove the right stick from the donor machine. On these 'cheaper' models the sticks are wired directly into the console rather than having a handy DIN plug so there's no other option than to remove the top.

First, pull off that giant knob. (No sniggering at the back.)

Insert Schoolboy Joke Here.

It should come as no surprise that the case of the donor machine is suspiciously like the case on mine, even down to the holes that are drilled in the back, but covered by a stick on plate on the donor machine.

Holy moley Batman!

It did come as a surprise at how 'cost reduced' this unit actually was. The video cable was soldered straight into the back and the 'modulator' for RF is basically a tiny circuit board with a few resistors on it...

Nothing Fancy Here

There are also large gaps in this circuit board where components could have been installed, presumably for other models.

What would go here I wonder?

Donor Unit Top case - spot the speaker...
There's no speaker in this one, or rather, there is, but it's a tiny piezo thing in the top case rather than a proper speaker in the bottom of my soon to be repaired unit.

My unit for comparison - it's still not exactly an XBox..
My unit, in comparison, has a proper speaker and an attempt at a separate RF modulator unit. Note the green wire which is the composite mod. Also note that the front 'dome' type buttons are identical between the units.

Looking left and right, the joysticks are connected to each far end of the board and I just cut the wires for the right stick and removed it. I did leave the grommet in the case, just in case this one ever gets put back to its original condition (unlikely, but possible).

It's very, erm, basic?
So now I have a joystick with a cable. What I planned to do was to desolder the cable at the potentiometers by disassembling the joystick. Then the block with the potentiometers will be soldered to the end of my cable which has the DIN plug on the end. At this point, I noticed something I hadn't expected. My joysticks had connections to all three lugs on each potentiometer. However, the donor unit only has two lugs connected on each pot.

One, two...oh, where's three?

Hmmmm. If I have time I may investigate further. I suspect that the donor console games may not have the complete range of movement that mine have. For now, I shall just swap the donor stick to my console.

This was easier said than done...

The wires in the original cable are quite short and the thick 'Vcc' cable was actually badly corroded when I opened it up originally. As a result of re-soldering, the wires are a VERY tight fit now. The end result was that the joystick worked perfectly. Almost.

For some reason, there was a noticeable 'jitter' from left to right on the repaired stick. Sometimes this would make the 'bat' jump from one side of the screen to the other then back again. Opening it up I realised that a strand of the 'Vcc' wire was loose and flexible and was probably making contact with one of the other potentiometer contacts. I removed it from the centre leg and re-soldered it to the other cable connected to that point. After another squash and a squeeze to get the thing back together, the bat was rock solid. But now it won't move left or right. Arse.

Pass me the screwdriver. Again. This time, I will solder longer wires to the pots then solder the original cable to them, making sure I use heatshrink to prevent any shorts. There's not a lot of room in them sticks!

This is taking longer than I thought...