How To Repair Circuit Ribbon

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I demand assistance to repair this ribbon cable

• Thread starter Trevor Rymell
• Start date May twenty, 2022

• #1

Can anyone suggest what solvent I might use to remove the shellac or varnish or whatever the coating is, from this busted ribbon cable? Information technology's out of an HP Elite x2 1012 G2 tablet and is the "bear on cablevision" which enables the bear on screen. The main display cable is fine and I can continue to apply the tablet with a mouse and keyboard.

But I'd like to attempt to repair it if I can. Equally can exist seen from the photograph, I managed to bridge the get-go ii tracks but had little success with the 5 thinner ones. The soldering iron kept melting the coating which contaminated the joint. I figured I'd have better luck if I could make clean the blanket off more effectively with a solvent (rather than trying to scrape information technology off with a bract). I might demand to cut the cleaved ends dorsum a bit and endeavour to span the gap with $.25 of fine insulated copper wire. I accept a expert demote microscope for SMT work then it shouldn't exist incommunicable equally long as I can get a few mm or then of clean copper on each runway.

Needless to say, if anyone can propose a better alternative method for a repair like this, I'chiliad all ears.

In case anyone is wondering, my first idea was to try to buy a replacement cablevision which is listed as p/northward 924453-001, Cablevision Kit in the Maintenance and Service manual which I assume means both cables. My local HP can't or won't sell me the cable(s) proverb I have to pay them to replace the unabridged LCD display screen with the cables. This would cost the best part of a $1000/-. I've searched all over for a supplier and can see the Cablevision Kit listed on many web sites with the toll merely so far haven't found one either with the part in stock or who tin ship to Singapore.
Cheers for reading
Trevor

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• #2

Endeavor an ebay search. There are flex cables for many products listed.

• #3

I've seen them but don't run into the one I demand. I tried every combination of search terms I could think of simply haven't had any luck and then far.

• #iv

But use very fine abrasive, eg. 600 or thou course, to carefully accept the top insulation off the flex PCB traces for a centimetre or so either side of the damage.

Then employ single strands of wire from a normal multi-strand cable, laid along each trace and soldered down so in that location is at least 5mm overlap each side of the harm.

For each trace, solder at one side while holding the end of a well over-length bit of shaped wire in place, and then cut the free end to length, concord that down with a jewellers screwdriver and solder that side.

If you start out with the strands of wire are 2 - 3 inches long yous tin easily hold them past manus to position the start end without the part you are belongings getting too hot. Bend the end y'all are gripping or make a small loop in information technology, so you lot can control the bending.

• #5

Thanks for this, rjenkinsgb. Information technology's gonna be a challenge for my 74 years old fingers, simply with the trivial Chinese Andonstar microscope I bought, I might go away with it.

I bought the scope and so I could exercise SMT soldering for the first time. All my feel prior to this had been with .1" through-hole PCBs using a normal x10 magifier but this is totally inadequate for SMT.

In that location were one or two .5mm pitch ICs to mount but with the scope and some really helpful YouTube videos virtually draw-soldering I managed to make a decent job of it.

• #vi

One thing that is really helpful with SMT soldering is LIGHT – the more, the better.

• #7

I had success recently scraping the insulation off the full general purpose course of this kind of cable (ie, patently ribbon) by scraping beyond the conductors with the tip of a precipitous craft knife. It was easier and quicker and more authentic than using abrasive. I suppose there's an increased take chances of causing more impairment yet.

I was going to advise 0.1mm magnet wire (cheap on eBay) for the repair, just rjenkins' suggestion is arguably easier. Magnet wire is neat if y'all're used to it...

Hot tip! When y'all finally get to really soldering the wires on, tape everything down before soldering. Kapton (or the cheap version, Koptan) tape is ideal, but you could use maskng tape. Sellotape/Scotch tape is stable, but melts as well easily (unless you take the very sometime cellulose stuff). I wouldn't use electrical tape, it has as well much adhesive on it and is too stretchy. Tape the ribbon to the bench, tape your repair wires to the ribbon. When you've soldered one stop, tape down the end you soldered before soldering the other finish (because the solder volition melt again and the wire will move and your beautiful craftsmanship instantly turns into a botched mess. I speak from experience!). If you experience you tin safely cut the wires later on they''re soldered in place, it'southward easier to apply long strands and trim them after soldering. (Only it's more important to not exercise more damage, obviously)

At that place are at least a couple of YouTube videos showing repair of these cables, might be worth a look.

• #8

Thanks again, throbscottle for the smashing tips. I've got the cable taped to a slice of fibre glass PCB and that's taped to the base of my scope so zippo moves.

I managed to become a couple of mm of the ends of each broken track tinned and and so soldered in ii bridging wires successfully. I was able to utilize regular Cellotape to anchor one stop of the wire with the other end cutting to correct length then I only had the spare wire at the anchored end to remove. In practise I found in that location was no trouble caused past the heated wire melting or softening the adhesive. Speed soldering the articulation is central.

I've never seen or used "magnet wire" only the all-time wire I could find was a single strand from the centre core of some RG-174 coax which is .15mm dia, blank copper. It worked fine one time anchored adequately and didn't need to exist pre-tinned.

Only 3 more to go! I'll postal service a shot of it if I tin can complete it successfully without getting over confident and botching the whole matter.
Thanks again
Trevor

• #9

Well information technology ain't pretty but it's electrically OK. I encapsulated it with some epoxy resin which should assistance keep the damaged department rigid. One time information technology has fully cured, I'll re-install the cablevision and keep my fingers crossed information technology works. Information technology was pretty much a nightmare working at such farthermost manification just as I've said, the biggest problem was the conformal coating that kept melting into a chemical sludge all over the joint. Acetone blast varnish remover had no effect. Gentle scraping works fine for cleaning the copper but the coating betwixt the tracks need to exist cleaned away. If I'm ever clumsy enough to damage a flex cable again and try to repair it myself, I'll put more attempt into tracking down the right solvent to go rid of that coating completely before trying to solder.

Still can't figure why it's so difficult to buy a new replacement. As I said in my first postal service, HP insisted on replacing the LCD display with the two cables attached and doggedly refused to accept that the cables are listed as a spare part with a part number despite me pointing this out in the very same maintenance manual they sent me. After all, the tablet is out of warranty and has been out of production for about 4 years.

My guess is they just don't want to release parts to retail end users for self repair. That could well be just local policy. HP Partsurfer in the Us/UK lists the cable kit and fifty-fifty quoted the price in Sing dollars simply will only ship to their home land. That would be fine but they have no stock and seem reluctant or unable to say when they will have them in again. There seem to be no shortage of like cables for other models on eBay and elswhere only not for this 1.

Many thanks to you and rjenkinsgb for all the helpful advice.
Trevor

EDIT: Happy to report my repair worked! My affect screen is working once again. Phew!

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Last edited: May 23, 2022

• #ten

Prissy looking repair. It's at least every bit good equally anything I could e'er exercise - well done!

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How To Repair Circuit Ribbon,

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