Assembled control board -
Board assembly to retainer -
Alteration of repeater LED wiring to thinwall 10/0.1 stranded cable to reduce wiring bulk -
The lamp lens can be parted from the base using a knife and then re-attached using polystyrene cement. A blob of 703 silicone on the back of the circuit board around the wires retains the board to the base and seals against water. Terminals for a KF2510 connector are crimped to the wire ends.
Polystyrene cement has to be allowed time to cure properly before repeaters can be attached to the mirror shells to avoid separation of the lens when the securing screws are tightened.
Addition of remote potentiometer (10/0.1 cables) and optic fibre indicators to mirror shell to avoid having to remove mirror glasses for setup and in service adjustment -
0.3mm diameter optic fibres used are cut from a £3 Lidl optic fibre lamp bundle as possibly the cheapest source compared to buying optic fibre by the metre. Larger diameter fibres and ferrules could be used but I've gone for small and unobtrusive.
Inset shows exterior view of optic fibres shaped to fit countersunk ends of the 1mm ferrules. Shaping is achieved by carefully melting the end of each optic fibre to form a crude lens; finished fibres are retained in the ferrules using 703 silicone.
The position of the indicators ensures that there is no direct view from the driver seat. Their main functions are to aid setup and service adjustments and provide means of fault finding should the system fail.
The 1x2mm silicone tubes are a tight push fit on the ferrules (outer diameter about 1.8mm) and need no adhesive to retain them.
The 1mm ferrules, the 3mm ferrule for screwdriver access to the potentiometer and the potentimeter board are retained using hot glue. Hot glue also is spread over the wires to the potentiometer board to provide mechanical support to prevent connection failure of surface soldered wire ends.
Short lengths of silicone tube and PVC sleeve are used to keep things tidy with heat shrink tubing covering the ends of the screws retaining the repeater lamp.
Control board installed in each mirror shell, all wires and optic fibres below the centre web of the mirror shell -
The remote potentimeter assembly is handed, the position being dictated by the mirror arm obstructing access to the lower edge of the mirror shell opposite the repeater lamp.
Optic fibres are cut flush with the ends of the 1x2mm tubes which require no adhesive to be retained by the 2x3mm tubes on the indicator LEDs.
Remote potentiometer wiring colours don't match circuit layout colours above: someone didn't check before gluing everything in place. Duh.
Upshot is reversal of the black and purple wires in the connector plug so that clockwise rotation of the adjustment screw increases temperature setting.
Mirror glass assembly connected to control board (right side) -
Trial fit -
The rubber seal has to be softened in hand hot water to ensure best fit all around the mirror assembly then held in place while it cools.
The fit of the glass in the mirror head shell isn't very good when new - hence the hot glue to cut through when dismantling new mirrors - and as a result the rubber seal barely covers the edge of the glass due to the mica sheets adding to the thickness of the heated glass assembly.
The simplest remedy is to resort to adhesive again once I'm happy with the installation wiring and can finally finish each mirror assembly. Clear silicone seems to be the best option because it will stick to the mica sheets surface and can be parted more easily than the original hot glue.
Meanwhile some burn-in is required so that I'm sure everything works as intended: lash up test rig -
The K-type digital thermometers are the older version of what's available on eBay. This type can be calibrated because the circuit board is provided with low and high range adjustment potentiometers (low range being closest to the display). Once a meter is taken apart two of the four holes beneath the label that align with the potentiometers can be punched through from the front and then covered with a date label after each calibration.
Calibration for the range 0-100°C is sufficient for present purposes, i.e. range between temperature of melting ice and boiling water, the latter adjusted to accommodate atmospheric pressure. Calibration of two meters so that they agree to ±0.5C is possible by ensuring that they respond together to small changes in temperature. Actually nice kit for not a lot of pennies; the later versions for much the same cost have no provision for any adjustment and can be adrift by more than 10°C but can be identified by the label being different.
The 14.5V supply is a 12V 30A unit maxed out on the voltage adjustment to simulate maximum voltage of the vehicle charging system. The control unit and switch are a story in themselves ...