TrRob Posted April 16, 2014 Report Share Posted April 16, 2014 From the TR4 workshop manual: Illumination of the tachometer and speedometer is controlled by a switch at the left side of the tachometer. Is that the same for a TR4A and where is that switch located? (i only have the TR4 workshop). The gauge illumination lamps are not connected by mine TR4A and according the wiring diagram I have these are connected to the gauge lamp dimmer control. regards Rob Quote Link to post Share on other sites
Geko Posted April 16, 2014 Report Share Posted April 16, 2014 on 4As all instruments lamps including tacho and speedo are connected to the dimmer switch Quote Link to post Share on other sites
peejay4A Posted April 16, 2014 Report Share Posted April 16, 2014 ...and the dimmer is located in the switch plinth. Quote Link to post Share on other sites
RogerH Posted April 16, 2014 Report Share Posted April 16, 2014 ....and the dimmer switch goes from - dim to dimmer to off. Not the best device after 50 years of iffy wires and dicky contacts. Roger Quote Link to post Share on other sites
Grahamgl Posted April 16, 2014 Report Share Posted April 16, 2014 I dismantled the one in my car,cleaned the contacts and, now it works perfectly. Graham Quote Link to post Share on other sites
peejay4A Posted April 16, 2014 Report Share Posted April 16, 2014 ....and the dimmer switch goes from - dim to dimmer to off. Not the best device after 50 years of iffy wires and dicky contacts. Roger Mine's shiny and new with new wires and works. Sort of. Quote Link to post Share on other sites
TrRob Posted April 17, 2014 Author Report Share Posted April 17, 2014 Thanks Quote Link to post Share on other sites
Geko Posted March 14, 2016 Report Share Posted March 14, 2016 (edited) Not sure if I'm opening a can of worms in resuscitating an old thread but mine never worked properly, not even the brand new one. It's always been the "0/1" sort of thing but no real progressive dim. The next mission is to see what's inside and try to make this work. 1/ The threaded part is bent so I'm going to straighten it and put it back perpendicular to the housing (2) 2/ The hexagonal rod (3) is coming off just as if there's nothing to retain it inside. Surely it must be sealed somewhere either with a circlip or sealed to one of the parts i.e. (5) ? Part missing? 3/ Shall I remove the resistance (1) to clean it or just brush it gently in situ? 4/ How do I test the resistance to see if the dim effect is the expected one - while the switch is dismantled? Thanks for your advice Edited March 14, 2016 by Geko Quote Link to post Share on other sites
AlanT Posted March 14, 2016 Report Share Posted March 14, 2016 You a want Scotch-brite pad. Look on ebay. Made in UK by Mirka I think. This will quickly brighten all the metal bits. I would not mess with the resistance winding unless its not joining up to the teminals. Just buff the tops where the contact hits. Quote Link to post Share on other sites
Geko Posted March 14, 2016 Report Share Posted March 14, 2016 Scotch brite I have, so that's one done... Quote Link to post Share on other sites
RogerH Posted March 14, 2016 Report Share Posted March 14, 2016 Hi Stef, the centre contact area needs to be cleaned thoroughly as does the brass sweeper that sits on it. As Alan stated do not remove the resistance coil - simply clean the area where the sweeper arm makes contact. Make sure the external contacts are clean. If you put a resistance meter on the external contact and the end of the of the coil then you will get zero at one end and the full resistance at the other. If you run the lead along the coil the resistance will vary in a uniform manner. Having spent ages doing a deep clean your lights will now be enthusiastically dim. What is required is a brightener. Roger Quote Link to post Share on other sites
Geko Posted March 14, 2016 Report Share Posted March 14, 2016 (edited) Thanks Roger, I think i found the fault: With the wear the arm of the sweeper tend to bend upwards hence not providing a frank and steady contact with the resistance. I bent it downwards so that the contact is frank throughout. I guess the spring (4) will need to be strengthened. Edited March 14, 2016 by Geko Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.