Tag: computer control

I refer you to the post I wrote earlier in June 24: Teenage jealousies revisited

Here I purchased the toy I most wanted back in my teenage years. Unfortunately I wasn’t available to get the original MB version produced in 1979 so I had to settle for the latter “improved” version made by Zeon Ltd that was made in 2010.

It’s arrived and to be honest dosen’t look too shabby, needs a bit of a clean up and maybe some new transfers applying but we’ll get to that at another time, for now we need to try and get the machine up and running.

I’ve eventually managed to get the lid off. This unit was built to ensure that it was difficult to get into so repairs couldn’t be carried out. Some of the screws are buried under fascia dressings, and if you aren’t careful you could end up snapping some of the body shell.

With the two halves of the body shell detached it’s obvious there are some detached wires. One was a battery wire, one was a speaker wire. Oh if this was the issue wouldn’t it be great? But it wasn’t. I soldered these wires back into place, put the three D types in place and it was still dead.

I’ve now desoldered all connections from the circuit board to assist in carrying out checks for continuity and tracing voltage. I can also check the board under the microscope. I may change all the capacitors for SMD ones.

I started checking continuity and tracing voltages and was doing really well until I got to a large section of the main board where everything seemed dead and unresponsive. What the heck was going on here? And then I noticed the wire had detached from the positive probe of my multimeter thus ending any further testing for today. I need to order some new probes. Well, I’ve ordered some nice new probes and croc clip connectors as well, so as soon as they arrive I’ll get back on with the testing. They arrived and were damaged on arrival, so back to the drawing board.

I took the drive train to pieces and here it became apparent that a number of the cogs are damaged. I believe there is also some issues with the motion detector but I can’t confirm that until I get some power into the motors. I can’t find spare cogs online so I have ordered myself a second damaged unit to use as salvage. To be honest this new unit has all the transfers in place so I will probably use that shell and the guts of my original unit to form one complete Big Trak.

The donor unit has arrived and boy I’m impressed. It’s in far better condition than my original one, so as expected this one will become the working unit and my original one will be come the donor. Any parts left over will be sold on as spares or even used on another damaged one if I can source it.

If you look at the video above you will see the new Big Trak going through the motions. However the one thing it dosen’t do is turn. Could be a wheel sensor issue who knows. Good thing is that the cogs haven’t broken as the drive wheels are both solid and not free wheeling.

There are only two real issues with the donor here. Firstly it will not do the turn command and secondly, one of the drive wheels is damaged. Luckily I have a spare wheel so this was swapped over, some decals were missing but I coaxed these off my old truck with a hot air gun and reapplied them with no issues.

Looking into the drive issue meant opening the gear box. In here we have two magnetic independent gear controls that should have a gap between them, these two were stuck together thus rendering independent motor operations of the turning control useless.

I removed the two motors and repositioned them and the cogs holding the magnetic gear, this gave a gap of about 3mm that now allows the wheels to turn in opposite directions allowing the unit to turn.

Whilst in this gear box I was able to confirm the issue with my old gear box and it really is all down to two damaged drive cogs that I need to obtain. I’m pleased with that as I could now get two good working units for just a small outlay once I can source some cogs. I will have to repair the wheel I removed to replace the one on my new unit however I have an idea how I’m going to remedy this and again it’s a low cost option. But that’s a job for another day.

So if you look at the video above, it’s the full fix that I posted on YouTube. Really pleased with this fix, again I’ve learned quite a bit about these units and I’m going to have immense fun programming it. My wife dosen’t understand my excitement over this toy, but all my old buddies and colleagues understand it as they grew up in the same era. Maybe it’s the male menopause, reliving the past and all that.

But hey, it keeps me occupied and out of mischief so who should worry about that

This one is going on my shelf so when the kids visit I can show them the joys of basic programming we experienced back in the day.

Job done.