Motorcycle dash button failed - Page 1
Forum section: electronics / beginners

author: Various
author_rank: Contributor
timestamp: November 10, 2019, 07:30:07 pm
content: Hi,I am new to electronics, so please excuse any errors and feel free to point me in the right direction!I have a 7 year old motorcycle with an electronic (LCD?) speedometer and buttons for switching between displays, but one button has stopped working. This is a known failure for this dash but it seems that no owners have been able to fix the problem and manufacturer replacements also fail. I am trying to understand the failure and then see whether a repair can be made, the part is very expensive to replace!There is a theory among some owners that UK bikes suffer the failure more than American bikes, maybe the problem is associated with climate and therefore corrosion?I have removed the dash from the bike and removed the workings from the outer casing for inspection.I carried out a continuity test on the switch to see whether it works, and it seems OK.I can see what looks like corrosion on the PCB trace, but I would like any feedback on whether this looks like the problem.The PCB is printed with 'NS 06901'.I will try to attach some photos to show you what I can see.So...Do you agree the problem seems to be corrosion of the PCB trace?Is it realistic to make a repair to the trace?To get access to the trace, I think I need to remove the PCD display, but this seems to mean removing the solder for all of the pins (see photo), am I correct?ThanksMatt

author: ataradov
author_rank: Super Contributor
timestamp: November 10, 2019, 07:59:30 pm
content: It is corrosion, and the repair is very possible. But it looks like the corrosion is around something that was not soldered before. Where is the actual button? Where do those holes go to?

author: Various
author_rank: Contributor
timestamp: November 10, 2019, 08:10:54 pm
content: Quote from: ataradov on November 10, 2019, 07:59:30 pmThat is good news!Photos attached showing both sides of the PCB to help give an idea of what goes where.Thanks

author: ataradov
author_rank: Super Contributor
timestamp: November 10, 2019, 08:17:11 pm
content: Ah, ok, this is (was) a plated through hole. This is a trivial repair for someone moderately skilled with a soldering iron.All you need to do is scrape the green solder mask from the trace on one side and on the other side after the corroded part. Then run a wire though the hole and solder it on both sides.Alternatively you may trace where the trace goes after it goes under the plastic. It is likely that it goes to the big black chip, so it must jump sides one more time. If you trace where it appears on the same side as the button solder points, you can just solder the jumper wire there right from the button.It is a good idea to clean the corrosion in either case.Find literally any electronics repair shop and they will fix this in 10 minutes.

author: Various
author_rank: Contributor
timestamp: November 10, 2019, 08:45:53 pm
content: Thanks!I will try to trace where it goes; the position of the corrosion makes it very awkward to reach because it is almost behind the plastic and I think that removing it would be quite difficult (for me!).I will look for an electronic repair shop to make the repair, but I would like to be able to repair it myself too. I might go and practise the repair on an old PCB to see whether my skill is as high as 'moderate'.Thanks again.

author: techman-001
author_rank: Frequent Contributor
timestamp: November 10, 2019, 11:42:48 pm
content: Quote from: Various on November 10, 2019, 08:45:53 pmTake your time and remember to NEVER FORCE ANYTHING or you'll just wreck the pcb. If you're stuck at some point, walk away from it until you have a clear new approach to try.Use "solder wick" to try and get the LCD pins free of the pcb but it won't be easy. If you can't wiggle each pin easily in the hole when you've removed the solder but you prise up the display anyway you'll probably pull the VIA guts out of the board and lift copper tracks ... don't ask me how I know this.Once you have repaired the board and it all works, then you have to figure out a solution to stop the water getting into the display in the first place. Is it condensation or rain ?If it's rain, it may be a good idea to make up a sensor to detect water in the display while you try your solution out because this will probably be the really hard part to monitor over a period of time.

author: ataradov
author_rank: Super Contributor
timestamp: November 10, 2019, 11:59:06 pm
content: I would not remove the LCD. There is no need to. Everything you need for a fix is accessible with LCD in place.

author: techman-001
author_rank: Frequent Contributor
timestamp: November 11, 2019, 12:27:44 am
content: Quote from: ataradov on November 10, 2019, 11:59:06 pmI think it may have to come off because:1) The corroded area is under the plastic LCD mount and is much smaller than the magnified view in the pictures. Access may be very hard and promote pcb damage.2) The button is within the plastic LCD mount and may not come off (if damaged by water) without the LCD being removed.3) If water is getting inside the cluster there could be more corrosion under the LCD. Of course if the OP can clearly see there is no problem under the LCD then as you say, there may be no need to remove it.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 11, 2019, 12:33:58 am
content: I am surprised that the board is not conformally coated.The motorcycle environment is harsh. Is not only plain moisture ingress, but that the road may still contain salts used during the winter season.Plus many owners pressure-wash their bikes, and you'll have soaps and other chemicals.

author: Various
author_rank: Contributor
timestamp: November 11, 2019, 10:39:56 am
content: Having looked at it carefully, I can see no other corrosion at all. I have contacted a Tech Repair company to see whether they can repair it. I'd rather practise my skills on something an awful lot cheaper to replace!Other owners with the same problem have also expressed surprise and disappointment that the unit is not better protected.

author: techman-001
author_rank: Frequent Contributor
timestamp: November 11, 2019, 11:07:48 am
content: Quote from: schmitt trigger on November 11, 2019, 12:33:58 amConformal coating isn't all win-win. For instance if there is a electronics failure, the board can be virtually un-repairable depending on how tough that coating is.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: November 11, 2019, 11:18:36 am
content: You can fix that with a piece of 30 AWG wire wrapping wire (google "ok 30 awg kynar").

author: AndyC_772
author_rank: Super Contributor
timestamp: November 11, 2019, 11:41:53 am
content: Don't touch the LCD pins; I can virtually guarantee that you'll do more harm than good unless you're already experienced in this type of PCB rework.Personally I'd start with an abrasive fibreglass pencil. Use it to remove the corrosion and the solder mask on the affected trace(s), so you can clearly see where any breaks are. It'll also leave a clean, oxide free surface that you can solder too.Bridge any breaks with solid core wire as advised above. Even if it's just a hairline crack, using copper wire (which is ductile and not brittle) will give a longer lasting repair than just a solder bridge, which can easily fracture under vibration.Test before reassembly, obviously. Once you're happy that it's working, it would do no harm to coat the area with a protective layer - though it could be argued that the problem is water getting inat all, not that there's any particular issue with that specific part of the PCB.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 11, 2019, 08:11:29 pm
content: Quote from: techman-001 on November 11, 2019, 11:07:48 amEngineering is the art and science of compromise of conflicting requirements.It is true that a conformally coated board may become un-repairable, but it would be better that the board does not become defective due to environmental factors.Clearly a motorcycle environment qualifies as a challenging enviroment.But again, when one is designing a product, and a business case is being made, these decisions are made.

author: m3vuv
author_rank: Super Contributor
timestamp: November 11, 2019, 08:41:47 pm
content: what make and model bike is it?

author: Various
author_rank: Contributor
timestamp: November 17, 2019, 09:13:53 am
content: Quote from: AndyC_772 on November 11, 2019, 11:41:53 am

author: Various
author_rank: Contributor
timestamp: November 17, 2019, 10:40:45 am
content: Now that I have re-read the advice given to me previously, it is starting to make sense.I have now found where the trace runs to (by using a continuity test) and proved it by inserting a wire between the two points as shown in the photo. I have tested this on the bike and it works!1. Should I now be looking to solder a wire permanently in place to make the same link as the temporary wire shown?2. Is the information in this video by Manchester University good?4. Is it likely that this connection could affect another function? The bike obviously has other functions, an alarm, immobiliser etc so should I test the different functions before making the repair permanent?Thanks for your help.

author: AndyC_772
author_rank: Super Contributor
timestamp: November 17, 2019, 10:45:51 am
content: The feature you've circled looks like a through via, ie. a plated-through hole which forms a connection from one side of the board to the other. If it's a multi-layer board, it could connect to internal layers too.If you don't measure continuity from one side of the board to the other, then that's good insofar as it means you've located an electrical fault that can be fixed. It may not be the only one, but you have to start somewhere.Clean up both sides of it with a mild abrasive - emphasis on the "mild" - so you have clean, shiny copper exposed. Poke a short length of solid core wire through the hole and solder it on both sides, job done.

author: AndyC_772
author_rank: Super Contributor
timestamp: November 17, 2019, 10:51:28 am
content: ps. the photo you've attached of a wire link ishorrible.Hanging a wire that fat and heavy off a couple of tiny vias is just asking for them to be ripped off the board under vibration, and that'll leave the board in a state which is much harder to repair. All those spare copper strands waving about in the breeze won't do any good if they touch anything else either; at the very, very least they should have been trimmed back to the insulation.If that's the repair you need to do, use 30AWG solid core wire as advised above, and tack it to the PCB with superglue so it doesn't flap about. A couple of tiny dots are all you need, don't go mad with the glue, and don't get any on the solder joints just in case you ever need to repair them.

author: Various
author_rank: Contributor
timestamp: November 17, 2019, 11:26:26 am
content: Quote from: AndyC_772 on November 17, 2019, 10:51:28 amHa ha, sorry, that was just a bit of wire I had laying around and used it to test that I had found the correct parts. It is going in the bin soon!So I can just superglue the new wire in place??? Brilliant!I have read that the areas where I removed the mask should be re-coated with epoxy, is this correct?Thanks again

author: Various
author_rank: Contributor
timestamp: November 17, 2019, 11:37:59 am
content: Quote from: Various on November 17, 2019, 11:26:26 amYou didn't mean I could replace the solder with glue did you?! You meant glue it to the PCB to stop it flapping about after it has been soldered at the ends.Sorry, this is in the 'Beginners' section for a reason!

author: Rerouter
author_rank: Super Contributor
timestamp: November 17, 2019, 11:43:58 am
content: correct, superglue to support the wire after it is normally soldered (soldering near superglue will sting your eyes and nose worse than you can imagine)To prevent the weak vias from possibly being damaged by the weight of the wire as the bike will go over bumps etc,

author: Various
author_rank: Contributor
timestamp: November 19, 2019, 03:52:20 pm
content: Well, it's fixed!No doubt the experts would have done a lot better job, but for me it has been interesting and rewarding. It has also saved a whole lot of money and prevented a usable component form being thrown away.The photo shows the wire I soldered between the two points.Thank you to everybody who helped me.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 19, 2019, 04:19:30 pm
content: Quote from: Various on November 19, 2019, 03:52:20 pmThanks for reporting back. That's definitely not a terrible repair. It looks like it may be a bit susceptible to vibration in its current form but now you know what to do! Maybe you could fixate the wire with some hot glue. That would also allow you to remove it all later on.

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: November 19, 2019, 04:36:04 pm
content: It's not horrible but it isn't perfect either: You should have left less exposed wire at the ends... I would put a bit of kapton tape under the exposed wires at both ends. That, or a drop of thermoplastic just to be sure it can't touch the pcb traces underneath.

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 19, 2019, 04:52:31 pm
content: Quote from: GeorgeOfTheJungle on November 19, 2019, 04:36:04 pmHot glue!

author: GeorgeOfTheJungle
author_rank: Super Contributor
timestamp: November 19, 2019, 04:58:23 pm
content: I mean... hot glue!

author: AndyC_772
author_rank: Super Contributor
timestamp: November 19, 2019, 08:47:29 pm
content: I see the recommended dot of super glue at the bottom end, so no issues there.I can't see one at the other end, and if there really isn't one, it would do no harm to add it even if it gets onto other components.That aside, I'd call it a perfectly serviceable repair, and I've seen much, much worse. Nice job!

author: Various
author_rank: Contributor
timestamp: November 19, 2019, 11:15:59 pm
content: Quote from: AndyC_772 on November 19, 2019, 08:47:29 pmThe superglue is indeed there at one end. I didn't put it elsewhere because I would have been gluing directly onto a solder joint or a trace - is it OK to glue to those?But thanks for the feedback anyway, much appreciated. There's so much bare wire at the ends because I wasn't sure how close it could be without melting and causing solder problems. So definitely a 'beginner' thing on my part.

author: ataradov
author_rank: Super Contributor
timestamp: November 19, 2019, 11:43:32 pm
content: Quote from: Various on November 19, 2019, 11:15:59 pmYes, it is fine. Superglue is not conductive.But I would also put a few glue dots along the wire as well. Vibrations will break the cantilevered mass. They may not seem like much, but there are a lot of them and they are consistentIt does not have to be superglue. Hot glue would work as well.