Ideas for how to clean and reassemble an extremely complex busbar assembly - Page 1
Forum section: electronics / general

author: arsenix
author_rank: Contributor
timestamp: March 03, 2024, 09:31:20 pm
content: I am rebuilding the fuse/relay box from my Porsche 944. This is quite a complex design. I theorize that in the 1980's Porsche hired some engineers who escaped from a nearby asylum!It is a plastic enclosure with 7 "sheets" of plastic inside it. On each of these sheets is around 20 copper buss bars that have connections to fuse, relay, or spade connectors. When assembled you plug the fuses and relays into the top. Various chassis power wires plug into the bottom. The one in my car has a few flaky terminals so I'm digging in and seeing how to rebuild this. I have a few of these to play with.Although complex it isn't too difficult to take apart. I have now completely disassembled one of them. I cleaned all the plastic bits and I'm left with somewhere from 100-200 copper "bus traces" which I'd like to clean somehow before reinstalling. I believe they are pure, unplated copper, but I'm open to opinions on that topic. The lower connections (the spades) are all pretty clean since they were covered from weather. The top connections are a bit more worn and are pretty dirty. I'd obviously like to avoid hand scrubbing each one! I'm wondering what suggestions the community here has for cleaning this sort of thing up. They may have a small amount of dielectric grease on them but are otherwise just "dirty". I could use something like QD Electronics cleaner to spray them. I could soak them in vinegar (or something stronger?). There isn't a LOT of corrosion on them but there is some where it matters (at the fuse/relay terminals). I have an ultrasonic cleaner although it isn't large enough for some of the bigger ones.I'm also wondering if I should put anything on them when reassembling. A dielectric lubricant or grease etc? After disassembling one of these I'm hoping to only reassemble once!Some photos of the "layers" are attached as well as it assembled. There are 7 layers! I can't imagine how much time it took to design and manufacture these back in the 80's likely without any CAD.

author: coppercone2
author_rank: Super Contributor
timestamp: March 04, 2024, 09:52:53 am
content: it looks like a good design to me just missing fiber glass. no solder joints seems niceyou could clean them in a ultrasonic cleaner with copper safe cleaning solution (important). obviously try on one.for something like that probobly re-ultrasonic cleaner it for a few seconds in DI water, then rinse with fresh DI water from a squirter, blow dry as much as possible and then let it dry in a chamber with desiccant (non corrosive, like the clay kind). I noticed if you just throw them in the oven sometimes it tarnishes a bit randomlywith regular cleaners I saw some metals rapidly tarnish.short duration. I recommend you pull the dirtier ones for more controldielectric grease will be good. from the sound of things silicone based anything will be fine with the plastic. the danger is using a grease that can damage the plastic.I recommend doing it on one piece to make sure its OK, then work in small batches. don't dump everything in anything unless you are really sure.you might hear citric acid but be careful. I left something in the Ultrasonic cleaner for like 10 min with citric acid (it was not meant for this, I thought it was soap) and it actually started plating the wall of the cleaner ! don't ask me how, I assume it made a battery!it is very much on duration. it will be clean enough in short order, its not a magical repolishing machine BTW. The copper looks nice because it was mechanically stamped or polished or some shit. you can get rid of the oxides but it won't look quite right unless its repolished. electropolishing if you wanna fuck with that, IMO hard.the mistake you can do is over-do. a quick clean for 30 seconds should be enough.but the maintake is do gradual experiments and there is no magic bullet (maybe plasmaelectrolytic polishing is, but good luck with that setup! normal electropolishing is not that hard compared to plasma version). there is also electrocleaning, which is different then electropolishing. all the electro process are hard to execute compared to a quick ultrasonic dip BTW. I have some threads on electrocleaning and polishing (the brush process though is different and that is for nasty ass weld stuff). I consider it fun and even did a quick electroclean of a VNA test fixture before lol, but that shit is very technical. the problem is often that you don't have uniform field. with plasma you do but complex geometries = harder to electroanything. you are talking masking etcjust renember very good rinsing and soaking etc in distilled deionized water at the end unless you want spots to appear when dry when working with copper and chemicals! tap water can make it go off.

author: indeterminate
author_rank: Regular Contributor
timestamp: March 04, 2024, 10:30:09 am
content: Isopropanol & a tooth brush for a general wash.use a glass fiber pen for cleaning the contactsand finally clean the contacts with DeoxIT Contact Cleanerwitch will leave a film that protects the contact fase from corrosion.

author: jonpaul
author_rank: Super Contributor
timestamp: March 04, 2024, 10:55:45 am
content: that epoch of German cars used horrible Bosch electricn fule inhj and other controls.All the realsy get oxidized contacts.In 1970s used to see the Porches and similar lined up by side of highway wioth every rain.Remove relays, ise ISO alchols on all contacts, open relays if piossble.Then contact cleaner.Unless copper (NOT busbars) is completely corroded, no need to clean every conductor, only the contact surfaces.j

author: arsenix
author_rank: Contributor
timestamp: March 05, 2024, 06:14:16 pm
content: I ordered up some deoxit and a fiberglass scratch pen. This first one really isn't too bad. I know the one that is installed in the car has some known bad connections I will have to inspect. As usual it is a few of the "higher powered" ones that are the biggest problem areas.

author: coppercone2
author_rank: Super Contributor
timestamp: March 05, 2024, 08:35:51 pm
content: the surface finish gets destroyed by fiberglass. Its OK for spot cleaning corrosion but that even scratches up nickelIMO its a good tool to make something solderable but IDK about a contact

author: arsenix
author_rank: Contributor
timestamp: March 05, 2024, 09:14:17 pm
content: Hmm. Interesting.I'm still unsure about the finish on these contacts. I wonder if they are brass plated copper? I thought they might be pure copper but I can't imagine they would be this clean in that case given their age.

author: coppercone2
author_rank: Super Contributor
timestamp: March 05, 2024, 09:57:23 pm
content: it might be oxygen free its very possible their cleaned, also greased slightly.