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Portable radio problem

pewe

New Member
My wifes favourite portable radio has started to play up.
First, a few days ago it would take a little while after switching on before the radio played. Then it stopped and would not play at all.
After checking the fuse I took the back off to check if any components had overheated etc - nothing.
So I put it back together and tried it - it turned on and played immediately - for a good 6 hours or more.
Today we are back to square one and it won't play.

Attached is a photo of the inside - can anyone suggest which components may be causing the problem?

radio.jpeg
 

pewe

New Member
Thanks,
I'll have a look at the on/off switch.
Would a dry joint have been good for at least 2 years before giving up.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
The "click" of the volume/switch can crack a joint after many uses.

The other thing to try with that is just operate each of the push switches a dozen or so times - the contacts in those can tarnish if they are not used for a long time & operating them cleans the contacts.
 

pewe

New Member
It turns out it IS the spring on the on/off switch. Thanks for the suggestion.
If I turn on the switch there is a gap between the contacts, and when I push it over with a screw driver the radio comes on.
If it is turned off it does not reconnect when turned on again as the gap reappears.
The contacts are too small and fiddly to bend to compensate, and I'm not sure where to start in an effort to find a replacement, so I have told TOH that she will need to use the wall switch to turn it on and off for the time being.
I may solder the contacts together and fit an external light switch if I can't find a replacement.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
It turns out it IS the spring on the on/off switch. Thanks for the suggestion.
If I turn on the switch there is a gap between the contacts, and when I push it over with a screw driver the radio comes on.
If it is turned off it does not reconnect when turned on again as the gap reappears.
The contacts are too small and fiddly to bend to compensate, and I'm not sure where to start in an effort to find a replacement, so I have told TOH that she will need to use the wall switch to turn it on and off for the time being.
I may solder the contacts together and fit an external light switch if I can't find a replacement.
It looks a pretty standard small radio control - but most companies selling spares have long since gone bust, and it's not easy to source such items these days. We use a similar looking control at work, but with a splined shaft, and we import them from the USA.

However, you might have a look here:

 

pewe

New Member
It looks a pretty standard small radio control - but most companies selling spares have long since gone bust, and it's not easy to source such items these days. We use a similar looking control at work, but with a splined shaft, and we import them from the USA.

However, you might have a look here:

At that price I'll try them. Thanks
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
You could look for a volume control. e.g. https://www.ebay.com/itm/264890256042?chn=ps&mkevt=1&mkcid=28

the value may be stamped on the side, e.g. 5K, 10k, 50K. Volume is a log taper. You can also measure the end to end resistance, At 1/2 rotation, it won't be half the resistance because of the taper.

Retrofitting an external switch might be your best option because you won;t be wearing out the volume control. Looks like plenty of room to mount it on the case.

Here https://www.digikey.com/en/products/detail/nkk-switches/M2011SS1W03/1049529 is a typical miniature toggle switch. There is a little plate with a small protrusion. You drill a hole and then drill a tiny hole for the small protrusion. It prevents the switch from rotating, Generally, you tighten the switch from the rear nut.

they make them in a locking version too. You have to pull the handle and then move it.

A rocker switch https://www.digikey.com/en/products/detail/switch-components/RF1-1A-DC-2-B-1/11492654 is a possibility as well.
You may need a a Dremel tool, file or nibbler to install.

Personally, I'd probably go for the rocker.

Hint: Post-it tape is good to write the outline on. You can also use a coping saw. Drill the 4 corners. Thread the blade through the hole and cut.

Pilot point drill bits will drill a round hole. You can get them at www.mscdirec.com under the dewalt brand. Automatic center punches are nice. but that's an extra $20.00 USD. Drill a pilot hole first,
 

Nigel Goodwin

Super Moderator
Most Helpful Member
You could look for a volume control. e.g. https://www.ebay.com/itm/264890256042?chn=ps&mkevt=1&mkcid=28

the value may be stamped on the side, e.g. 5K, 10k, 50K. Volume is a log taper. You can also measure the end to end resistance, At 1/2 rotation, it won't be half the resistance because of the taper.
If you're measuring end to end, why would the value vary when you moved the pot?.

It's not critical anyway - and typical usual values were 5K or 10K - if you can find apot that fits, don't worry about the value.

You can also use a coping saw.
Have we entered a time warp? - I've not seen a coping saw since I left school a VERY long time ago :D

You mentioned Dremel above, easier to use a Dremel, and more likely that people would have one (or more) in the 21st Century.
 

Les Jones

Well-Known Member
Most Helpful Member
I also have one. I use to use it to cut rectangular holes in aluminium front panels before I had a milling machine. Woodworkers would probably not approve it's use on metal.

Les.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
I also have one. I use to use it to cut rectangular holes in aluminium front panels before I had a milling machine.
That to me would have been a job for an "Abrafile" or rat tail file, which was an essential tool for chassis bashing in the 70s - but apparently long extinct.

The originals were about 1/8" diameter and 8 - 10" long from memory, set in a normal wood file handle.
They were a formable iron rod with hardened teeth all around that could cut in any direction, brilliant for cutting profiled holes or slots.

You can still buy tension files that fit a hacksaw or coping saw style frame, but the single handle version no longer exists other than occasional mentions of the name.

This is the nearest I can find, which looks something like but is actually a tiny dentists tool..

 

Les Jones

Well-Known Member
Most Helpful Member
I still have a few Abrafiles and the adapters to use them in a hacksaw frame. I also still have chassis punches for B7G and B9A valve bases from the days when the first part of a project was making the chassis. I don't think I still have a chassis punch for octal valve bases.

Les.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I still have a few Abrafiles and the adapters to use them in a hacksaw frame. I also still have chassis punches for B7G and B9A valve bases from the days when the first part of a project was making the chassis. I don't think I still have a chassis punch for octal valve bases.
I've recently bought a couple of larger chassis punches at work, I've never had any valve ones :(
 

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