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Hi all,

I sometimes have a problem with lowering one or two light pods on my 1990 Turbo SE.

I should add first, that I have already some time ago changed the nylon bits to delrin ones, and the gear to cnc aluminium gears, in both light motors. Really smooth operation.

If I raise the pods on the main beam on the stalk switch, they always come up. Rarely they don't go down, but it happens.

If I drive with say position lights on, and "blip" the overtaking light (quick raising and lowering of high beam), they tend to stay up, not lowering again, in an increasingly mode of operation. So, sometimes they don't lower again.

 

Fuse 25 and 26 are fine, and besides they raise (and sometimes lower).

Any movement the pods do, up or Down, is silent, speedy and smooth in operation, with no change in speed, like for example if gears were crushed, smoething stuck inside etc. No worries there.

I've been looking for the relay - pod delay module, green, and changing that did not produce any change.

I read about some transistors burning off of excessive heat, and even burning of the circuitry board.

I took off the module, which is super easy with just two philips screws on the rearside of the left hand light pod (I drive a lhd car).

From outside there are no indications of problems, like melted wires, Black connector pins etc. No worries.

I opened teh module, which is held together with 4 small tabs and a think line of waterproofing sticky Black gum (to be reused). Easy peasy.

So, I took a look at the transistors, which I understand are mosfets. Correct?

I also think they are enhancement mode N-channel versions. Correct?

There are no visible Brown look around the transistors, no bad solderings anywhere to be seen or touched. That is not leaving out a bad soldering anyway, but no visible traces.

Usually these mosfets go Brown, leak a bit, melt or miscolour the surrounding area a bit, but no traces of that.

How do I test them on the board or should I solder them out and then test?

What is the switch voltage?

Is the voltage on my Fluke 179 enough to flip them in operation?

Any other components known to fail, which I should test?

Anything else I should do?

I google the writing, say M839 (type) and get loads of results, but clicking on those, I get other types. So, where can I get two new or two similar ones (types)?

I see that Lotus Marques in the USA have a repair kit ready, but I'd like to do it myself if possible, and besides the price go up 400% before landing here on my desk ;)

As there is ample toom for enhancements, I's also like to add two small heatsinks with a dab of heatpaste, to keep them cooler in the future.

 

So, any input as to testing, operation, solutions etc?

All inputs greatly appreciated.

Kind regards,

Jacques

 

module off.JPG

opening module.JPG

module open.JPG

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All that unit does is pulse 12v on the motors to lower or raise - it changes polarity from memory.

is it both affected or just one ?

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Sometimes one, sometimes both.

I should add, that I cannot feel any point that pods need to pass, like something holding them in aany given position, when I turn both pods knobs. They both seem super smooth in operation. But of course, one never knows. Any good idea on how to figure that out, or test?

Maybe the realy inside the module sticking?

Jacques

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I had a mare with my S - are you absolutely sure the motors aren’t packed with cruddy old solid grease ?

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1 hour ago, Jacques said:

So, I took a look at the transistors, which I understand are mosfets. Correct?

Here is the datasheet for them http://uk.rs-online.com/webdocs/0026/0900766b80026b3e.pdf

1 hour ago, Jacques said:

Any other components known to fail, which I should test?

IC1 is known to sometimes fail.

1 hour ago, Barrykearley said:

All that unit does is pulse 12v on the motors to lower or raise - it changes polarity from memory.

It also uses current sensing to cut the power when the motors stall due to the pod hitting the stops.

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4 minutes ago, sailorbob said:

It also uses current sensing to cut the power when the motors stall due to the pod hitting the stops.

And that would explain the utter randomness of the issues I experienced until I stripped and cleaned both motors

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Thanks for the datasheet.

When I redid the rollers and the gearing in mine, they were of course totally spotless, cleaned, greased up with special grease for the purpose of exactly those headlamp motors. They still run very smooth and light both.

Kind regards,

Jacques

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When I stripped and did mine - I removed all the specialist grease - cleaned and washed everything through and reassembled with very little grease. They are nylon cogs and as such need very little in the way of lubricant. 

Its worth checking. I do remember many hours of cursing and swearing with these motors. I wish you the very best of luck and will watch with interest for when mine break next time

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I greased the gears, not the rollers. They are delrin and don't need grease. There's probably a tiny bit anyway. They are supersmooth. The grease came with the kit.

I think it would be great id we could establish a sort of rest and repair procedure for everyone to benefit from, if at all possible.

Kind regards,

jacques

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Definitely - it nearly mentally broke me. 

At one point I even fitted mx5 motors - and found them to stick. I ended up resoldering every joint in that pcb, buzzed out everywire and cleaned every contact. Cleaned and fettled with both motors.

it drove me to drink - really badly. 

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I contacted them recently, they have the repair kit to replace the mosfets

https://lotusmarques.com/info/technical/30/689-esprit-head-lamp-lift-module-part-number-a082m6363f-repairs-part-1

they informed me they have stock but when I tried to place an order they did not reply me.. maybe you want to try contacting them?

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You can buy the BUZ102S mosfet still, or a more modern equivalent like this one.

http://www.weisd.com/test/GenericParts_WEISD_view.php?editid1=BUZ10S2

I would then just make a heatsink myself with a thin piece of aluminium. They probably don't get that hot I would imagine, although those linear regulators are not very efficient. I try and use switching regulators in anything I do.

If mine were to fail, I would slightly modify the case so that the heatsink would go through the case to the outside, so it will be able to cool properly in the air. Otherwise it could heat up inside a closed case. You could still seal it with silicon afterwards to stop water ingress. The heatsinks would not be damaged by the water if it was sealed.

Edited by Glyn Harper

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