I have cleaned, and cleaned, and cleaned the selector switch using Servisol contact cleaner (UK's equivalent of Deoxit). I have also disconnected as many plug in connectors - single and multi-way - that I can see, and cleaned those. I have removed eight fuses on the 'middle' PCB and cleaned and checked them. And FWIW, basically because its wafers are easily accessible, I have cleaned the tape switch too. I have looked at the underside of most of the PCBs for poor or dry joints and nothing found. The result of all that cleaning and checking? no change; still a flashing red protection LED and just the power meter bulbs lit. Oh, I pulled and checked the signal strength and centre tuning meter bulbs and they are good, but like I say, they're not lighting up. I realise that they should only light up when the selector switch is set to FM.
I decided to perform bias and quiescent current checks. It soon became apparent that the page of the Sansui service manual covering this is erroneous. That is to say, the words, the diagrams and the silk screened legends on the PCBs do not tally. Can someone who has dealt with this please clarify what pot adjusts what and exactly where the relevant pots and fuses physically are? Oh, and the fuse ID silk screens are hidden under the fuse holders. And to add insult to injury it says adjust the left hand bias current to 50mV.. So, by now I'm not very trusting of this service data!
Also, those driver circuit board adjustment instructions are pretty vague re which speaker outputs to use, where to set the speaker switch, loads etc. I'm assuming that you use speaker output terminals 'A' (for example) and then set the speaker switch to match, ie 'A'. Any load connected or not?
