Makingtrax Posted May 26, 2023 Share Posted May 26, 2023 My 2016 Knaus Sun Ti is having problems with the light switches. Each switch can switch on 4 lighting banks. See photo. They are pressure switches with a printed circuit board behind the plastic cover with a ribbon cable attached to the PCB. Unfortunately they’re not all working no matter how hard you press them. I suspect I need a new PCBs, unless someone knows how I can fix them. Knaus say you can only order parts from a dealer, but my nearest dealer (Derby) says they’re not selling parts to the public anymore. I originally bought the van from Lowdhams, but they are no longer a Knaus dealer. Any help much appreciated. Link to comment Share on other sites More sharing options...
Alanb Posted May 26, 2023 Share Posted May 26, 2023 You state that the switches are "pressure" switches. I interpret this as membrane switches similar to those used on some TV remote controls rather than something like a touch screen. If you can non destructively gain access to the synthetic rubber membrane, and clean the inner surface with methylated spirits, you may be able to make an inexpensive cure. I have used this technique on TV remote controls. Alan Link to comment Share on other sites More sharing options...
Makingtrax Posted May 26, 2023 Author Share Posted May 26, 2023 5 minutes ago, Alanb said: You state that the switches are "pressure" switches. I interpret this as membrane switches similar to those used on some TV remote controls rather than something like a touch screen. If you can non destructively gain access to the synthetic rubber membrane, and clean the inner surface with methylated spirits, you may be able to make an inexpensive cure. I have used this technique on TV remote controls. Alan Thanks. Yes they’re membrane switches. The outer plastic cover sits over a metal dome that squashes flat. I didn’t know they could be cleaned. I assumed the metal dome had somehow lost it’s springiness and therefore it’s connection when flattened. As the metal domes are part of the PCB I assumed it would need a new pcb. They’re only small, but getting hold of parts seems very difficult. Link to comment Share on other sites More sharing options...
onecal Posted May 26, 2023 Share Posted May 26, 2023 Hi Disconnect from the power source.Take the switch off , mark the wiring or take a photo of it Try some gentle heat from a hairdryer and replace , it make take a few tries to work, If that does not work , you could try taking it apart and clean (not really recommended) Otherwise you may just have to go to a dealer , or replace with ones similer to same Regards Link to comment Share on other sites More sharing options...
Makingtrax Posted May 26, 2023 Author Share Posted May 26, 2023 Thanks. Willing to give that a go.You think there might be moisture in there from the winter storage? To get parts I’ll have to find a dealer willing to send for them, which could be easier said than done. Link to comment Share on other sites More sharing options...
Keithl Posted May 26, 2023 Share Posted May 26, 2023 If it could be moisture then try putting the switch unit in a plastic bag with either desiccant or dry rice. Both should draw out any moisture. Or maybe just leave it in the sun for a few hours 🌞 Link to comment Share on other sites More sharing options...
Makingtrax Posted May 26, 2023 Author Share Posted May 26, 2023 8 minutes ago, Keithl said: If it could be moisture then try putting the switch unit in a plastic bag with either desiccant or dry rice. Both should draw out any moisture. Or maybe just leave it in the sun for a few hours 🌞 Thanks very much. I’ll see if I can disconnect them and give it go. It’s strange that 3 of the 4 banks of 4 switches have gone the same way. Each of them has one or two not working. Link to comment Share on other sites More sharing options...
onecal Posted May 26, 2023 Share Posted May 26, 2023 Be very carful of the sun as it is known to cause damage The phone trick with the rice and plastic bag may also do the trick Gentle heat is all that is needed and you may need to do it quite a few times Regards Link to comment Share on other sites More sharing options...
Makingtrax Posted May 26, 2023 Author Share Posted May 26, 2023 1 hour ago, onecal said: Be very carful of the sun as it is known to cause damage The phone trick with the rice and plastic bag may also do the trick Gentle heat is all that is needed and you may need to do it quite a few times Regards OK thanks. Going to take them apart tomorrow and dry them out thoroughly to see if that’s the cause. I notice I have a slight problem with the membrane switches on the Alde control panel too. Damp could well be the problem even though we put lots of moisture absorbing crystal containers around the van in the winter. Link to comment Share on other sites More sharing options...
onecal Posted May 26, 2023 Share Posted May 26, 2023 Hi Just be careful and apply very gentle heat , Take your time Regards Link to comment Share on other sites More sharing options...
Makingtrax Posted May 27, 2023 Author Share Posted May 27, 2023 I’ve now managed to take the whole switch assembly apart and they’re not membrane switches, but tactile push switches on a PCB covered in a layer of plastic. One of the switches has just stop working when you push it. May have to contact Knaus to get the make and serial number of the exact switch in order to get a replacement, and then brush up on my soldering. Link to comment Share on other sites More sharing options...
Keithl Posted May 27, 2023 Share Posted May 27, 2023 Try a squirt of electrical contact cleaner then exercise the switch a few times, it may dislodge any crud and get you back in action. Link to comment Share on other sites More sharing options...
MikeF Posted May 27, 2023 Share Posted May 27, 2023 Replacement switches are available, try eBay, https://www.ebay.co.uk/sch/i.html?_nkw=momentory+tactile+piush+switch+pcb+mount Or RS uk, https://uk.rs-online.com/web/c/switches/keyboard-keypad-switches/tactile-switches/ Mike Link to comment Share on other sites More sharing options...
Makingtrax Posted May 27, 2023 Author Share Posted May 27, 2023 1 hour ago, Keithl said: Try a squirt of electrical contact cleaner then exercise the switch a few times, it may dislodge any crud and get you back in action. I’ll try that first thanks. Link to comment Share on other sites More sharing options...
Makingtrax Posted May 27, 2023 Author Share Posted May 27, 2023 1 hour ago, MikeF said: Replacement switches are available, try eBay, https://www.ebay.co.uk/sch/i.html?_nkw=momentory+tactile+piush+switch+pcb+mount Or RS uk, https://uk.rs-online.com/web/c/switches/keyboard-keypad-switches/tactile-switches/ Mike If the contact cleaner doesn’t work I’ll order a few of these. The tactile switch looks like. 6mm x 6mm x 10mm high. Have to work on my soldering iron skills. 😂 Link to comment Share on other sites More sharing options...
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