{"id":841,"date":"2016-12-17T16:59:24","date_gmt":"2016-12-17T15:59:24","guid":{"rendered":"http:\/\/storycase.co.uk\/radio\/?p=841"},"modified":"2019-02-13T20:16:53","modified_gmt":"2019-02-13T20:16:53","slug":"roberts-r250-r550-volume-control-fault","status":"publish","type":"post","link":"https:\/\/storycase.co.uk\/radio\/common-faults\/roberts-r250-r550-volume-control-fault\/","title":{"rendered":"Roberts R250 \/ R550 \u2013 Volume Control Fault"},"content":{"rendered":"

Do you have a Roberts Revival R250 or R550 radio with no sound or crackles when the volume is turned? It’s a common problem with these radios after a few years use. The on\/off switch attached to the volume control can break causing no sound so the control needs replacement. Or if the speaker makes a crackling sound all you need some switch cleaner or if that fails a soldering iron and some spare parts and it’s a fairly easy fix.<\/p>\n

Warning – this gets technical but it’s really not difficult and you can have your radio working again in an hour or so.\u00a0Please take take when using soldering irons.<\/p><\/blockquote>\n

Crackly or noisy controls may be fixed using some switch cleaner which is available from outlets like Maplin for under \u00a35 look for aerosol Switch Cleaner<\/a>. Make sure it has a small flexible tube with the can so you can direct the cleaner inside the volume control. It works best if you place the end of the tube in the small slot by each of the three wired connections (see below) and turn the control back and forth fully after squirting in the cleaner. No need to use too much – just a quick press is all it should need. You don’t need to remove the volume control as in the picture below.<\/p>\n

\"Roberts

Roberts R250 \/ R550 volume control<\/p><\/div>\n

If there’s no sound at all (see Roberts R250 \/ R550 – No Sound Faults<\/a>) and the on\/off switch has broken or the crackle remains after cleaning you will need to replace the volume control.<\/p>\n

Finding replacement volume controls is not too difficult however getting one the right size is. You need a 10K\u03a9 (kilo ohm) logarithmic potentiometer with a switch. You may notice the original one fitted is in fact a 20K pot or rather two 20K (stereo) pots wired in parallel to make 10K. The shaft length needs to be at least 15mm with a flat area to fit the volume knob. Most parts I’ve found have a 6mm splined shaft (see below the 2 on the right) so need filing or grinding flat. If the shaft is too short you may need to shorten the daughter board fixing studs (see later).<\/p>\n

\"Roberts

Roberts radio R250 \/ R550 volume controls<\/p><\/div>\n

Replacing the volume control requires removal of the main radio PCB (see other\u00a0post for how to do this) to gain access to the daughter board that contains the volume control. Remove\u00a0the two daughter board mountain screws (they may be held with\u00a0red lock paint that will crack and free). Next unsolder the grey ribbon cable that attaches the daughter board to the main board.<\/p>\n

The volume control can then be removed from the daughter board by unsoldering the small board that connects the potentiometer or removing the wires if there’s no additional board. Solder braid or solder suckers helps the unsoldering process along with small pliers to avoid burning fingers! Please take care when using soldering irons they do get hot enough to melt tin.<\/p>\n

If you have found replacement pots like those shown you need some small lengths of wire to connect the pot and switch to the daughter board. There are five connections the two outer ones are for the on\/off switch and the inner three and the volume potentiometer. An example of fitting a shorter replacement is shown below.<\/p>\n\n\t\t