850 ABS-unit failure in hot weather after first resoldering?

Hi Franz,

I did the ABS module repair to my 1996 - 850 about 2 years ago and have not had any problems since. The two large pins were the source of the problem, I couldn't see any cracks in the soldering of the small pins. I have worked in electronics for many years so a reliable repair did not present a problem.

Your symptoms still sound like a broken solder joint. The cable hanging off the two big pins can put quite a large mechanical load on them if the cable vibrates at all, and they may have broken again if you didn't do a good job first time around.

As you didn't glue the lid back on (getting the lid off was is the hardest part of the repair), and the unit is reasonably easy to remove from the car, I suggest you have another look at it. Inspect the two big pins carefully with a magnifying lens and a strong light before you try to resolder to see if your previous soldering has failed. As the board has plated through holes, use a large enough soldering iron (60 watts or so) and take enough time to properly melt the solder right through the plated hole. If you haven't the expertise or tools, you should try to find someone who can do it for you. Make sure you remove the conformal coating from around the pins before you start (carefully scrape it off), and use the proper rosin cored (or similar) solder sold for electronics work. It wouldn't hurt to re-seal your work after you finish. I like nail polish (I steal it from my wife). Clean off any excess flux using alcohol or similar first.

Temperature cycling can effect broken soldered joints just as you describe, but the failure will eventually become "all the time".

I you do repair it successfully, I suggest you re-seal it properly after you're happy with it. Use a neutral-cure silicone sealer (read the label). Ordinary silicone sealers contain acetic acid which is not good for electronic circuits. Good luck

Barry

Franz

Just a footnote to your question and maybe related?

I had the same warning lights on my car (1997 850R) and it turned out to be the ignition switch contacts had worn. A new switch cured the problem. Quite an easy fix but you do need some of those new fangled 'Torx' gizmos to get the screws out.

ttfn.....Alistair

"Baz" schrieb im Newsbeitrag news:0218d923$0$20655$ snipped-for-privacy@news.astraweb.com...

I have done some home soldering which I learned from my father who was a hobby electronic fan until the advent of transistors.

I think I did not dare to use a 60 W iron, it was probably a 15 W iron. I was afraid to cause damage to the components by excessive heat.

I did it with a little Dremel - type tool, was actually not very difficult.

Did you take any precautions to prevent excess heat flow to the components? Or is it that the two big pins are the DC supply lines and there is no other connection than to the plug outside the box? Maybe I really give the job to an electronic shop, who has the proper equipment. Still cheaper than a refurbished unit or one of the repair services offered.

Good idea. I did not reseal it last fall.

I do already have a product Hylomar at home suggested by experts. I did not yet glue the box together since I wanted to see whether the soldering lasts - apparently not. I will do the job within the next weeks when I have time..

Regards Franz47

"Alistair Ross" schrieb im Newsbeitrag news:gue1s9$3u9$ snipped-for-privacy@gemini.csx.cam.ac.uk...

Thanks for the input. Sounds definitely more expensive than the soldering job, which helped last time - unfortunately only for some time. I have bought a set of those Torx-screwdrivers and the one nut necessary for removing the ABS-unit. Also elsewhere on the car there seems to be exclusively Torx-screws. Franz47

"Baz" schrieb im Newsbeitrag news:0218d923$0$20655$ snipped-for-privacy@news.astraweb.com...

Hi Franz

The two pins in your small circle are the two that needed re-soldering on my unit. I did resolder a couple of other suspect joints on the "long connector" but the two pins on the separate connector were definitely cracked.

I had no worries about this type of work as the last 45 years of my working life (yes, I'm and oldie) has been in electronics. This is what I'm familiar with.

As you do not have any electronic components really close to these pins, overheating semiconductor parts is not a problem, and quite a large amount of heat is needed to successsfully resolder them, due to the size of the pins. I'm talking about leaving a 60watt iron in contact with each pin for up to 5 or so seconds (depending on the iron), and making sure the solder melts on both sides of the PCB.

Have a good look at your previous work before you touch it, to make sure it needs reworking. And as I said before, if you're not happy to do the work yourself, try and find someone else who can for you. It's not something you want to write off if you can help it :-(

Regards Barry

All of the ones that are circled are likely suspects. Notice the big heavy pins and the large ground plains surrounding them. It's difficult to wave solder a board that has a mixture of fine and heavy stuff like that, hot enough to really flow well on big heavy connections is hot enough to fry small sensitive parts.

Sucking up the old solder does hurt, but usually it's not really necessary unless it's really oxidized or contaminated. You just have to make sure you get the joint hot enough that the solder flows together completely.

You shouldn't suck up the old solder, it will burn your lips ;>

Use a solder sucker, it is a soldering iron with a suction bulb on it. There is also solder wick which is a stranded copper braid with rosin solder flux in it.

It is best to use an experienced technician to do solder> Make sure you suck up(the tool is cheap to buy) the old solder and clean up

Hi Glenn

Thanks for the offer to help. I found some screws at home with probably the same length and diameter with an Inbus head I have bought last year as a future replacement, when I had seen that the Torx heads were worn. I haven´t been successful finding the screws yet. When the originals are out and the unit at the electronic repair shop I will see whether my screws fit or not. In case not I will return to your offer. If your e-mail address is correct, I will contatct you through it. Regards Franz47

Dull or shinny is not a deal breaker. The trick is that the solder must WET both surfaces it is soldering together. When the solder doesn't wet one surface, you get what is called a cold solder joint. It is a mechanical joint but not a metallurgical joint like you get when the solder wets a surface. Most cold joints have a nice shinny surface. The factors that determine success and failure include:

Tools:

The right size solder tip for the job and the right surface on the tip for the solder you are using. Don't use a 1000 watt gun when you need a

The right solder for the metals you are joining. Use the right amount of tin.

The right flux for the solder and the metals and the size job you have. It must be a non-corrosive flux.

The right tip temperature for the job. Too hot or too cold won't work.

The right heat sinking for parts that need to be protected from excess heat. Soldering one thing can make something else fail.

Technique:

The knowledge to know how to prepare the surfaces.

The knowledge to know how to prepare the tip on the soldering iron.

The knowledge to know where to apply the heat.

The knowledge of how much solder to apply and where to apply it.

The knowledge to know when both surfaces have been wetted properly.

It is not a trivial thing. Many people are lucky and get by. I few people know what they are doing and get it right every time. I worked for AT&T Bell Labs and our technicians could tell when an engineer did a solder job. I was an engineer and usually got it right. The technicians got it right every time.

I had the unit repaired now at one of the very few still existing electronic repair shops in a city of 1,6 millions for a reasonably price. The guy said it was quite a job to clean and resolder the indicated connections but it seems to be ok now. After installing it and turning on the ignition, the ABS- and TRACS-lights went out quite quickly. After dysfunction before the repair often the lights stayed on until having driven about 10-20 meters, first then they went out. Tempomat and speedometer work. I have not hat a chance to test the ABS-function here in the city but will test tomorrow in the countryside on a gravel road but if the unit survived my soldering work last year, it must have survived the work of a craftsman. If that works I will take it out and seal the surface of the circuit and the box. I was not successful to find definitely acetateless clear high temperature silicone so I will use a spray sold in an electronics market meant to cover circuits with a film against moistness etc. For sealing the lid I have something appropriate. Hopefully this will be the last work on the unit for ever!! Franz47

"Stephen Henning" schrieb im Newsbeitrag news: snipped-for-privacy@news.isp.giganews.com...

It´s done now. I went to a local electronics repair shop, yes very few of them are still around nowadays here, chatted quite a time with the guy there. He resoldered it for a reasonable price, told me that it was a nasty job to get the contacts cleaned. He suggested to istall it first preliminarily to check function and heat tolerance, all ok now, so today I sprayed the electronic-circuit-sealant onto the circuit, sealed the lid with a silicone like high temperature resistant sealant, changed the screws and hopefully will never never have to bother about the unit. Thanks again for any input Franz47, Vienna, Austria