POST 17: The orange bike- BALLAST RESISTOR

The Ballast Resistor 

I have already started to reconnect the electrics on this orange bike. This process was very similar to that on the blue bike. However I needed to make a new retainer for the front basket carrier which carries the front indicators and headlight. I also needed to refit the rear indicator bar (including ballast resistor) which holds the rear indicators, as well as the number-plate holder which carries the rear tail light/brake light combination. I also changed the ignition switch and fitted a new battery (AGM type). The wiring seems to be functional for both parking brake lights and indicators.  

The ballast resistor was missing from the rear indicator bar and although I had acquired a spare, it didn't look to be in good condition; the wiring insulation had broken and the ceramic  insulator was cracked. I measured the resistance and found values of 1-10Mega ohms - far too high as the cited value is only 3 ohms! New resistors are a silly price, so I thought I'd investigate further. The resistor matrix seems to be held in by a folded crimp so I tapped that back progressively.

Opening the resistor by bending back the retaining tab

Once released the resistor matrix came out up to the crack- but surprisingly the resistance element was just a coiled wire and this was unbroken despite the crack in the ceramic.

I could gradually scrape the ceramic back and push the damaged wire up into the resistor exposing the break in the insulation and heat resistant sleeve.

Resistor matrix moved upwards as wire was pushed through

I'd expected to find a break in the resistance coil - but to my surprise as more became visible I could see that there was no break.

Progressively exposing the coiled resistor wire.

There was some internal corrosion that might have contacted the wire, but the wire itself was unbroken and uncorroded.

Testing the resistance coil itself showed that its resistance when measured directly across the wire (not contacting the case at all) was the expected value of 2.7- 3.2 ohm.

However when measured along the resistor and to the case itself, I again got values in the mega-ohm range. It seems therefore that the resistance element is undamaged but the mega high resistance is generated by its poor connection to the metal case. This connection is achieved through an aluminium rivet and I suspect this may have corroded at the steel/aluminium junction resulting in a poor connection. However, if this is so then it should be possible to repair the connection and hopefully salvage the resistor.

The wire also needs a new heat resistant sleeve. I cleaned out the remainder of the solidified insulation material so I could get at the rivet connection

Insulation removed exposing the rivet contact to the resistance coil.

I could then drill the rivet out...

...to release the end of the resistor which terminated in a wire loop.

Resistance wire coil detached from the aluminium rivet

I pulled the wire through the other end to release the resistance coil completely. I removed the damaged sections of insulation and slipped the remainder up to cover the core. I used heat shrink to mask and insulate any joints. However I needed a wider hole to feed the repaired wire back into position. Sadly attempts to enlarge the hole fractured the insulation and the plastic insulating grommet. I fashioned a new one from part of a crimp wire connector and pushed that into place.

Replaced insulation grommet

Having removed the rivet I fashioned a connection post for the other end from a  small brass bolt and 2 nuts. I used the first nut to fix the bolt into the resistor case.

... and used the second nut to fix the resistance wire to the post.

Resistance wire fitted in position- note new insulation emerging from plastic grommet.

Finally, I replaced the ceramic using wall filler (Tetrion) ensuring it flowed under the wire as well as around and over it to prevent the coil from shorting directly to the case. 

I rechecked the resistance from the connection lead to the resistor case and it now read 3.2 ohm. I left the filler to set before slipping a heat resistant sleeve over the flex to complete the fix.

Ballast resistor was then refitted to the indicator bar and connected to the bike wiring loom.