jayartibee Posted March 5, 2016 Share Posted March 5, 2016 Hi - I have a hardly-used Beltpack BP111 and the Mic switch is misbehaving. When the button is IN, you can hear yourself talk in the earmuffs but the rest of the network cannot. I have checked the Mic switch on the circuit board for dry joints but this hasn’t helped. The Mic gain adjustment isn’t the cause. Any ideas? Return to Canford? Link to comment Share on other sites More sharing options...
timsabre Posted March 5, 2016 Share Posted March 5, 2016 If you can hear yourself then the mic switch is ok, it is a problem with the line hybrid circuit, assuming you can hear everyone else ok. If you can't hear anyone other than yourself it's a line wiring problem. I'd return to Canford. p.s. the little adjuster is not mic gain, it is sidetone - the amount of yourself you hear in your headset. Mic gain can't be adjusted. Link to comment Share on other sites More sharing options...
jayartibee Posted March 5, 2016 Author Share Posted March 5, 2016 Ah OK - but there is a poor connection in the switch as, if you persevere and push the button hard it starts broadcasting to the network.. Link to comment Share on other sites More sharing options...
timsabre Posted March 5, 2016 Share Posted March 5, 2016 Look elsewhere on the board, when you press hard you will be flexing other joints too. As far as I remember the mic switch just shorts the mic which would affect both the local sound and comms line sound. Link to comment Share on other sites More sharing options...
Brian Posted March 6, 2016 Share Posted March 6, 2016 On the tecpro the mic on/off switch is a DPDT part. One section switches the output from the mic amp into the line drive/hybrid stage. In the off position it grounds that signal, along with the feedback path to keep the hybrid gain constant. The other pole switches the sidetone. In the off position the wiper from the sidetone pot is disconnected and the route it normally takes is grounded. So, if you can here yourself, but the network can't, then it's one section of the switch. I'd start by doing continuity checks of the switch in each position. Link to comment Share on other sites More sharing options...
jayartibee Posted April 1, 2016 Author Share Posted April 1, 2016 Replacement switches from Canford are... wait for it... £35 (owing to their minimum order policy) Where can I source a switch such as this from a more reasonable supplier? Link to comment Share on other sites More sharing options...
Brian Posted April 1, 2016 Share Posted April 1, 2016 Where can I source a switch such as this from a more reasonable supplier? 50p any better... http://www.rapidonline.com/electronic-components/toneluck-pbn-s2a1-5-aag-standard-2-pole-changeover-switch-white-78-0500 The photo is wrong, click on the datasheet PDF for a proper picture. P&P for small orders is £3.99 + vat Link to comment Share on other sites More sharing options...
jayartibee Posted April 1, 2016 Author Share Posted April 1, 2016 Bit better thanks - I tend to use RS or CPC and I'll try and cross-reference. Are PCB latching switches fairly standard then? Link to comment Share on other sites More sharing options...
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