ESD Safe soldering station loan - LCM fix

voxpop

Anyone have a lend of a ESD safe soldering station - ive the common LCM problem of blown transisters and need to solder in a new set. A lend of one would be much appreciated. In Dublin.

Onwardandupwar

If your on about the lcm on a BMW I don't think that's gona work as it does require coding there after if my memory serves me correctly

DublinDilbert

What size packages do you need to solder? Once you have a fine enough bit you'll be grand, may even get away with a heat gun.

If your stuck and around Dublin I'll solder it for ya.

voxpop

@ DublinDilbert: Its a transister or two. The guide I was reading said they were very sensetive to static and to use an esd safe soldering station. Ive always just used a cheap soldering iron,but I dont think its precise enough for electronics. If you're handy with a soldering iron, it would be a great help.

@ Onwardandupwar : you only need to code the lcm if its from another car. Replacing the transisters should repair the existing lcm

DublinDilbert

If the tip is fine enough on your existing soldering iron you should be fine. Depending on the design you might have to get a load of heat into them anyway to de-solder & re-solder them.

The solder joints just crack on these anyway right? Or are the transistors damaged.

Nearly every soldering iron will be Esd safe as the tip is earthed. You'll have more Esd than the soldering iron :-) do make sure to earth your self, handle the ecu by the ground connection initially. The person who wrote the how to is probably a little paranoid about Esd.

whizbang

do it on your kitchen sink, grounded steel worksurface is about the best you can get!

langdang

Don't wear a fleece shuffling round on carpets and you'll probably be fine.
Ground yourself off the sink as well before you touch anything to dissipate any static.

"Old style" lead solder is more flexible and is easier to get a good joint on than the newer lead free stuff. If the original issue is cracking of joints it would be worth using the lead stuff.

voxpop

Cheers lads - soldering iron is a standard draper yoke - probaby not good enough anyway for doing electronics.

Ive attached the guide I was going to follow

DublinDilbert

voxpop wrote: »

Cheers lads - soldering iron is a standard draper yoke - probaby not good enough anyway for doing electronics.

Ive attached the guide I was going to follow

It may just be cracked solder, in which case heating it up and adding some fresh solder will solve the problem. If you do need to replace the device the only tricky bit will be wicking/sucking the solder out of the holes.

If the part is gone, i've lots of the BTS441 high side drivers sitting around, they are just a more modern version of the same thing, should work the same.

cletus

DublinDilbert wrote: »

If you do need to replace the device the only tricky bit will be wicking/sucking the solder out of the holes.

http://www.amazon.com/Parts-Express-Solder-Sucker/dp/B0002KRAAG

voxpop

How do I know if the solder is cracked? I took the board out today, pic below. There is a bit of corrosion , would that be an issue?

DublinDilbert

It's some times hard to spot the cracked solder without a magnifier / microscope. Dry joints will be dull in colour and not shiny.

Definitely clean up the corrosion with ipa.

The solder typically cracks on large components that are mechanically attached to the pcb and something else too, a heat sink for example.

You can just apply some flux and reflow the joint, if you think its bad.

voxpop

Im guesing my soldering iron is way to clumsy for this sort of work ?

The transistors are pressed against the heatsink using some sort of spring clips - could that lead to solder cracking. Probably just replace the transistors , if I can get my hands on replacements.

When you say reflow - do you mean just heat up the solder and let it re-cool ?

DublinDilbert

voxpop wrote: »

Im guesing my soldering iron is way to clumsy for this sort of work ?

The transistors are pressed against the heatsink using some sort of spring clips - could that lead to solder cracking. Probably just replace the transistors , if I can get my hands on replacements.

When you say reflow - do you mean just heat up the solder and let it re-cool ?

Yea if the transistors are held against the heat sink, the solder going into the PCB can crack from vibration, expansion etc... I've seen this lots of times on car radio's where the amplifier chip is bolted to the case.

Yea re-flowing the joint, is just heating it up, usually with some solder flux added and allowing it to cool. This will generally fix a bad joint. if you've no flux, suck /wick some of the older solder off and add some fresh stuff.

I have lots of them BTS441 if you want a few of them. But I would re-flow the joints on the existing transistors before replacing them and test it in the car to see if it fixed the issue.

voxpop

is re-flowing something a novice could do - ive soldered a few things but nothing this precise

DublinDilbert

voxpop wrote: »

is re-flowing something a novice could do - ive soldered a few things but nothing this precise

Yea re flowing is a simple as it gets. If you have a flux pen just put a dab of flux on the joint, this will help remove the impurities and get the solder so stick better.

deandean

But beware Voxpop, you can damage components and even the PCB if you start cooking stuff. That soldering iron you are showing might be a 40-Watt; I'd be using a 15W iron there.

If you don't have good soldering experience and a suitable size tip on your iron, I suggest you beg a favour from someone who's good at soldering. Reflow is only a 15-minute job; replace transistor maybe 45 minutes.

Getting the LCM out of the car, and getting the PCB out of the casing is the hard & time-consuming part.

Is that corrosion on the PCB or is it heatsink paste?

Quite a few LCMs have failed 'cos of water ingress, water gets in, uh, bulkhead or door seal or somewhere and gets into the module. Check passenger-side footwell carpets are completely dry while you're in there.

Hope it all works out for ya

The LCM in mine failed on the input side; it was my first fault with the car & I went to a main dealer :eek: first they replaced the indicator stalk about €300, then the LCM another €600 (slight reduction after discussions). With hindsight, main dealers only replace stuff. With a car a few years old you want to be able to fix stuff, and that is where online forums & a good indy or two, really shine!

voxpop

yeah i was thinking I might head to maplins and get a smaller soldering iron and some flux and just try to reflow the solder - not sure it will work as this is a know problem with the LCM ( the bad transistors ) - but it seems the easiest option.

Its corrosion on hte PCB - the rest of the board looks in decent shape and there is no dampness in the car - getting the LCM out was the easy part for me

If anyone around dublin is decent with a soldering iron and has the time - there would be a few quid in it

whizbang

voxpop, where are u based. im mobile , maybe can help. BUT:
i have been repairing PCBs for years, but not with corrosion.
just doesnt last. even tiny currents will "grow" the corrosion right inside components .