Many thanks to SWLing Post contributor, Gabry Rizzi (IV3MIR), who writes:
Hi, I’m an Italian radio amateur IV3MIR and I have a YouTube channel entirely dedicated to the radio “GabryMir Radio”. I’m sending you the link of one of my latest videos. If you like it I would be happy to see it on your blog.
I hope the automatic youtube translator does a good job.
Cordially 73 and Happy New Year!
Gabry Rizzi IV3MIR
Click here to watch via YouTube.
Note that Closed Captions can be translated into English and other languages.
Thank you for sharing your video with us! I’m happy you were able to sort out the issue with your ‘660 encoder!
Replace failed switches. These are called tactile switches, dome switches or tactile keyboard dome switches. Dome switches are rated by switch cycles. To avoid early failure order quality dome switches with the highest cycle rating. I have ordered dome switches for other electronics gear rated up to 1,000,000 cycles. Example: https://www.digikey.com/en/products/detail/e-switch/TL3315NF100Q/1870394 . I’ve never had to replace dome switches on my Sangean radios and some are nearly 30 years old.
This also makes me want to ask others – I have a Tecsun PL-380 and the keypad quite early on developed rather ‘sticky’ buttons, or rather that some buttons on the numpad are very hard to press. Not actually sticky, they just require a lot of pressure to make them operate. Others are a simple ‘click’ and it registers.
Has anyone else had this issue? And more broadly, if anyone has a suggestion of how these types of buttons can be cleaned or repaired I’d be grateful. I’m not actually sure what they’re even called to be able to google it! They are the metal domed variety underneath the actual plastic button and they sort of click when pressed.
Are they traditional metal dome switches taped to the circuit board? Oftentimes the “tape” is more like a sticker layer applied over the keyboard PCB. I never used it, but Deoxit D100L is apparently used for dome switches. You peel back an edge of the tape or sticker, carefully pply the D100L to the metal surfaces, and stick it back down. I found a page showing the basic cleaning idea:
If needing replacements, you can buy traditional SMD/SMT metal dome switches at Digikey, Mouser, eBay, etc. You will need to know the size, number of legs, etc. Remove the defective key, cut ECD pressure tape (like Kapton) to size, and apply the new switch. I found a YouTube video showing the basic replacement idea:
Cheers, Robert! They are just the type you describe… I haven’t opened it up to check for a while but I got the impression they were a sealed unit and I didn’t want to try and peel anything away. But maybe I can to get in and clean them on the underside…
Time to open it up and have a closer look. Thanks very much for your tips.
BTW, I took a quick about the Deoxit formulas, D100 has no solvents, thus is supposedly more gentle. Typical D5 in a spray can does have solvents, which would likely not be good for the tape layer.
I tend to use CRC QD since it is often locally available at auto parts and hardware stores. It does not have “chlorinated solvents,” but it does have alcohol in the formulation, so again probably not something to use around sticky tapes.
Just to add to the above helpful info, I have found a video online which deals with this exact problem and on this exact radio:
The speaker is Portuguese but thankfully the Youtube auto-translated subtitles work nicely, and the video is really clear and easy to see what has gone wrong and what is happening. Looks like I know what I’ll be doing today!