Repairing Battery Op Robots

BACK

Repairing Robots - (Battery Operated)

Warning: you proceed at your own risk!

Unlike many battery op toys robots lack sophisticated mechanisms, and some faults are relatively simple to remedy. Beware though, if you lack confidence or manual skills then leave it alone! Dealers don't really mind buying non-working robots but they hate buying those that have been badly repaired. It's a policy you should also adopt when buying: if it's been hacked about then leave it. If you have a robot that refuses to work then I suggest that you do no more than attempt a repair from the outside.
Rule 1: Don't open the robot if you can possibly avoid it!
The moment you open a robot you begin to devalue it. No matter how careful you are, the process will leave signs behind that will warn off a potential buyer. Usually you'll leave scratches behind. Sometimes you'll discover that you're not the first to open the robot, AND THE TABS WILL DROP OFF. When you reassemble the toy you risk doing so inaccurately, and you'll have to dismantle it a second time to put things right. So don't do it. It's far better to have a non-working robot that is capable of being repaired when your better-off than to have a botched and valueless lump of tin looking at you for the rest of its life.
The usual problem is that the robot is a victim of lengthy storage. Try switching on and giving the toy good firm pat on the back. That is sometimes all that is needed. Clean up the battery contacts with fine abrasive. Ensure that the contacts press firmly against the batteries (you can often see a gap between battery and terminal, so the robot hasn't got a chance of working!) Put in strong, fresh batteries. Rechargables are ideal because they guarantee a good current. Cheap modern batteries have a concave base which makes them unsuitable.
Fiddle with the switch; you'll be surprised how often a toy burst in to life when the switch is in an in-between position. Now try to see if you can get at the pinion gear on the motor. A finger sometimes works (Attacking Martians are EASY!). If that fails try a long thin screwdriver blade. Use any orifice that will let you give that little brass or plastic gear a twitch, and I guarantee that you will have a high success rate. If you can't get at the gear then try for one of the gears close by. Ease it gently, you can damage the toy if you are too rough. Still not working? Some people wire an extra battery, to give the robot that additional kick. (And some people blow the light bulbs by wiring up too strong a battery)
At this point you need to consider the value of your robot. I've seen so many botched robots that I now suggest that you think hard, then LEAVE IT ALONE.
OK, well you were warned, but you're an obstinate devil. Time to go in for open heart surgery. Dismantle as little as possible. Open the key areas: usually the back panel or the panel that holds on the head. Don't use metal to lever the tabs or you will inevitably scratch the bodywork. Use a wooden spatula or a piece of thin firm plastic.
Rule 2: Make a note of how it goes together.
Look carefully at the robot. Make a written note of the wiring. You have no idea how difficult it can be to work out where a loose wire belongs! You'll find that more wires come loose as you repair a toy and you'll soon forget where they go. The information will also come in useful at a later date. Remember that many of the robots have bodies which act as the return wire: don't expect two wires running to each component. This can be a source of considerable confusion if you don't study the circuit carefully. You want access to a number of places. These are the areas I go for:

The motor: now you can reach it give the pinion gear a good clean up and spin it round.

The connections to the battery box. These frequently break loose, or the solder joints dry up with age. Repairs here are simple: a good clean up of the contacts and a light touch with the soldering iron.

Loose wires elsewhere. You can have hours of fun finding out where they belong! Look for traces of solder.

The switch. First check by bypassing the switch, otherwise you'll spend ages repairing something that isn't broken. Wires might be loose, but more likely is the problem of poor a contact between the switch components. A careful cleaning of accessible contacts can solve things, but It is tricky to repair a faulty switch mechanism and you may leave the robot in an unreliable condition. Switches are usually held together by tiny tags. It may rely on the springiness of the phosphor bronze components to ensure a good connection and you can easily damage the delicate set up.. If you have to replace the switch then find an identical one rather than a makeshift one.

Connections to the motor. Careful, these are delicate contacts. In my experience, the motors rarely fail. If they do fail then you have a much more complex repair on your hands and it is better left alone. Don't reassemble the toy if further repair is required.

If the motor runs but the toy does nothing the likeliest cause is the pinion gear again. In the late sixties the manufacturers started introducing plastic gears. The pinion gear just isn't up to it, and it splits. Replacing the gear with a plastic part is simple enough. You'll have to cannibalise a Japanese toy to get something suitable. There is rarely a compatibility problem. Brass gears don't split; they wear out. You'll see that the gears have a clear groove worn all round, and this prevents contact with the next cog in the engine assembly. If you have the right equipment you can ease the old pinion off and replace it with a new part. You should not try to remove a brass gear - you'll probably end up ruining the whole motor. Rule 3: Robot + Water = Disaster
Above all, don't immerse a robot in water, no matter how dirty it may be and how thoroughly you may intend to dry it. Water ruins the card insulators that hold the battery contacts and various internal switching devices. In addition sounding-box mechanisms and smoke-blowing bellows are often constructed from nothing more than paper or thin card. Water will distort and wreck these parts. You'd be amazed at how many people dunk the whole robot in bowl of hot soapy water.

SMOKE MECHANISMS
Many robots have a smoke mechanism which might need some attention to get it running. The smoke unit is a small enclosed metal cannister. The bulk of it contains wadding which has been soaked in light oil. There is usually a wick which is in close proximity to a heater coil, very similar to the element in a light bulb. When a current is applied the heater glows and vapourises the oil. A crude paper or plastic bellows blows a gentle current of air through the unit, and smoke emerges. Before you even consider a repair, try this drill.

Use strong batteries. The mechanism often won't work with weak ones.

Replenish the oil. Add only a drop or two of light oil, preferably the smoke oil sold by model train stockists. This oil needs to make its way into the smoke unit. Place it in the aperture where the smoke should emerge and give it time to seep along. I speed up the process by blowing down the tube, but it tastes horrible. Do not soak it! Too much oil is worse than too little.

Check the bellows. These often work loose or perish. Sometimes you just need to reseat the tube in the bellows unit. Holes can be repaired but the job is better left to an expert.

Dismantling a smoke mechanism is a job for an expert. You will almost certainly destroy the delicate element if you attempt your own repair.

© Brian Hayes 1996