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Triumph TR6 - Rheostat replacement

I am restoring the facia and instruments of my 1974 TR6. The variable resistor used to dim the dash lights is of the famous Lucas brand. Mine is the printed circuit type and I consider it behond repair. Parts of the printed tracks is missing. New ones are expensive, difficult to get and most probably not reliable anyway. I consider to install a true wired variable resistor like installed in TR4's but taken of the shelve of my local electronics supplier. Does anyone know the value in Ohms and Watts for this rheostat.
regards, Erik
E. Creyghton

Hi Erik

Remember outdoor weather and 12 volts. Your not drawing much current with the bulbs but at 12 volts its high compared to a housing voltage circuit.

I have used one designed as a tractor replacement for 10 years. $4 Canadian compared to $86.00 for original at that time. Had to file a flat on stem and shorten a bit.

Don't know original values but anything 12V auto rated should work fine as long as it fits. Find the bulb wattage add them all up and divide by 12 will give you amp load required. Not real critical as most are way over rated for safety.

Watch that nice wood :)

Bill
Bill Brayford

Bill,

I followed your advise, at present the newly veneered dash is with the paint shop of a ship yard to be sprayed. The panel looks great and I will send you som pictures when I have it back.

I was also not prepared to spend $80,- on a variable resistor of doubtfull quality.

Erik
E. Creyghton

I never understood why anyone would want to use the rheostat to dim already dim gauge lighting. When I have to pull my fascia, I'll bypass the rheostat entirely but leave it installed for appearance sake.

Rick O.
Rick Orthen

Rick
Smart move. IMHO, it is a waste of time and money replacing the Potentiometer with even a modern version (sorry Bill).
Even with a modern version installed one will still have it set to maximum illumination( pot set to zero ohms) which is exactly the same as the by-pass method (zero ohms). The by-pass method also eliminates a potential fire hazzard. I have said before...anyone with the original dimmer rheostat installed and connected should by-pass it totally and immediately.

If one wants to have the "original" capability of dimable dash lights then I totally agree...replace the old unit with a new modern one with suitable specs. ( 12 Volt..minimum 4 AMP... and if possible single turn).
Rick C
Rick Crawford

Rick,

I understand your arguing, non the less it bugs me to have a knob on the dash with no function whatsoever, so I still go for an alternative potentiometer. All the instrument lights take about 25 watt so your 4 amps example is safe enough to avoid fire hazard. As you indicated most probably the potmeter will not dissipate any heat because it will be turned to 0 ohms
E. Creyghton

This thread was discussed between 05/04/2003 and 07/04/2003

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