Control Lab sensors, wire replacement

[alexGS]

This is probably only of possible interest to a few people - the name BatteryPoweredBricks comes to mind :) I nearly posted it on the Control Lab Software thread before remembering that it is hardware, not software.

Also, this isn’t a post asking for help. It’s just an opportunity to share solutions (and learn any additional techniques that work) :)

The ‘rotting wires’ problem will be familiar to anyone who collects Control Lab, RCX, Scout, or Cybermaster LEGO from 1998-ish. Interestingly the insulation disintegration happens even inside the sensor housings as you can see in the first photo…  … so it clearly has nothing to do with sunlight, handling, cleaning products, or anything else - I think it is an unavoidable problem of the rubber-based material breaking down.

The replacement wire I use comes from China as silicone-insulated 5-way ribbon cable with a generous number of tinned strands (I think it claims to be 26AWG) - nearly as much wire inside as the original. 24AWG would be even better, but make sure the outer diameter is the same - 1.4mm per wire - 3.05mm across two wires (original is slightly wider at 3.18mm).

Here you can see a rotation sensor, a touch sensor, and a temperature sensor opened, with the replacement wires fitted. The light sensor (not shown) is similar to the rotation sensor.

 

For all sensors, I find it best to slice the corners where the housing is glued into the grey base. You can see where the blue or yellow housing material is sliced off flush with the base. A sharp, new craft knife is best for this. The four or six tabs along the sides of the housings should usually come out of the base as you pry them carefully apart with a blunt kitchen knife (if you use a screwdriver, only insert it where the wire is, to avoid marking the sides).

 

If you are very lucky, the cable retaining tab will come out of the housing with the cable (as it did here for the rotation sensor), but usually it will break off. To replace that, a thick cable tie can be cut into a short ~4mm serrated section that will press into the slot and hold the new wire securely.

 

The new wire has to be soldered in. The silicone insulation helps, as it does not melt back when you heat the wire. It also helps to use desoldering braid (or a vacuum pump) to clear the holes in the tiny circuit board of the rotation/light sensors. For the temperature sensor, I don’t try to remove the soft grey potting compound, but instead tease out two pigtails of the original wires and solder the new wires to those. It’s neat enough, and the instructions say not to immerse the sensor anyway, even though the original construction was clearly designed to be waterproof.

 

When you glue things back together with the superglue, be sparing, as you don’t want to create a big mess. A dot on the previously-sliced corners should suffice. I find those welding clamp pliers - Vise Grips with wide flat plates for jaws - very useful for holding parts tightly together without damage. Woodworking clamps wood work, too :D

If I’ve missed anything obvious or could have done a tidier job, please add your suggestions to this thread :)

 

Thanks for reading!

Edited August 9, 2023 by alexGS

[Toastie]

18 hours ago, alexGS said:

If I’ve missed anything

Hi Alex,

no, as far as I am concerned, you did not, in contrast. Your method works on 9V 2x2 connectors as well; yes, some are using the cutting blades again - I just cut them down and then solder. Carefully, as you do.

Thank you very much for sharing!

All the best,
Thorsten

[alexGS]

37 minutes ago, Toastie said:

 Your method works on 9V 2x2 connectors as well; yes, some are using the cutting blades again - I just cut them down and then solder. Carefully, as you do.

Oh - I get what you mean, soldering wires in the 2x2 connectors :) That would be a reliable solution and a good idea.

I don’t actually do that for 2x2 connectors; I use the original crimp method, which works fairly reliably with this correct-size silicone cable. But even so, sometimes the fingers (cutting blades) in the connector top get bent over and don’t work - I just straighten them and try again.

I think the topic of connector wire replacements has been covered quite well elsewhere; but I reckoned it was worth noting how to repair the sensors, since all but the earliest (shiny) wire is failing by now. The first few I cut open were a bit of a mess, but I’ve got better and I’m now doing all my sensors to be rid of the flaking wire problem for good. Cheers for your thoughts!

Edited August 9, 2023 by alexGS

[alexGS]

The early 9701 sets came with sensors having 104-stud wires (106 studs for the temperature sensor; the measurement includes the sensor body) and rather nice blue or yellow 2x2 connectors.

Later 9701 sets had much shorter wires, I think because the light sensor and rotation sensor were shared with Mindstorms RCX. Later 9701 sets also included 5x 69-stud wires to extend the sensor wires. Occasionally it’s a nuisance to incorporate the extra 2x2x4/3rd-height connection in moving parts of the builds.

I think from now on, I’ll make all the sensors with 104-stud long wires, even though I don’t have the coloured connectors. I suppose this will confuse historians like myself when sorting the sets, but the wire is not original anyway (original wires flaking apart are a real nuisance). What do we think?

[1974]

A link to the wire?

[Fyredog]

@1974 - Go here for wire.

I have repaired many 9V wires with GREAT success thanks to @BatteryPoweredBricks.  I haven't had to repair sensors yet - But Thank you @alexGS for your demonstration - I feel less apprehensive toward repairing the sensor wires using your method.

[Toastie]

12 hours ago, alexGS said:

What do we think?

@alexGS Your approach is 100% the way to go!!!

We should praise TLGs research department: They actually managed to use smart wire insulation material that - exposed to light or not, just not used at all or heavily bent back and forth - degrades terminally after 10+ years into slimy shreds of something. Even carefully heating this super smart material up makes things only worse. Congratulations on this one! Too bad, that the metal wires don't oxidize into some rusty crap - someone did not pay attention here!!! 

In conclusion: The historians will certainly cope with "wrongly" colored 9V terminals connected to new wires.

All the best,
Thorsten

[alexGS]

7 hours ago, Fyredog said:

I feel less apprehensive toward repairing the sensor wires using your method.

Perfect - thank you - that was my objective with this thread :) I wanted to help people make a neat job of cutting them open; my first efforts were a bit rough and I’d seen a video somewhere showing the use of a Dremel etc.

My own need for repairing sensors became apparent when the rotation sensors became flaky during a LEGO show and stopped working reliably. It’s very satisfying to restore proper function, and I think they will all need repairing at some point.

I really appreciate that you completed the information as requested by ‘1974’ with not just a link to the wire but a link to a guide for fixing the standard connector wires. That’s the strength of a forum!

8 hours ago, 1974 said:

A link to the wire?

Sorry for leaving out that information - here is the wire that I use. I order the 26AWG 5-core (make sure size is correct and also choose Color ‘5p 10m’) so the wire with the white stripe can be removed - yields 20m of 2-way cable. It’s wasteful throwing away the unwanted wire, but there isn’t a way to order the cable without the white stripe on one of the wires.

https://a.aliexpress.com/_mMnpxd8

 

 

Edited August 10, 2023 by alexGS

[Fyredog]

On 8/10/2023 at 2:36 PM, alexGS said:

Perfect - thank you - that was my objective with this thread :) I wanted to help people make a neat job of cutting them open; my first efforts were a bit rough and I’d seen a video somewhere showing the use of a Dremel etc.

My own need for repairing sensors became apparent when the rotation sensors became flaky during a LEGO show and stopped working reliably. It’s very satisfying to restore proper function, and I think they will all need repairing at some point.

I really appreciate that you completed the information as requested by ‘1974’ with not just a link to the wire but a link to a guide for fixing the standard connector wires. That’s the strength of a forum!

Sorry for leaving out that information - here is the wire that I use. I order the 26AWG 5-core (make sure size is correct and also choose Color ‘5p 10m’) so the wire with the white stripe can be removed - yields 20m of 2-way cable. It’s wasteful throwing away the unwanted wire, but there isn’t a way to order the cable without the white stripe on one of the wires.

https://a.aliexpress.com/_mMnpxd8

 

 

You can use the white stripe for hidden wires......