From: liz@poppyrecords.invalid.invalid   
      
   Chuck  wrote:   
      
   > On Thu, 14 Mar 2024 20:56:32 +0000, liz@poppyrecords.invalid.invalid   
   > (Liz Tuddenham) wrote:   
   >   
   > >I was asked to repair a Pioneer QX-949 quadraphonic tuner/amplifier.  It   
   > >is a complex beast and one channel had gone down to almost nothing.   
   > >Luckily the service sheet was available and I traced the fault to the   
   > >board which houses the tone controls and filters.   
   > >   
   > >The gain is in two stages with the tone controls around the second   
   > >stage.  On one of the channels, the voltages on the single transistor   
   > >for that stage were all wrong.  After lifting the transistor off the   
   > >board, it became apparent that the base bias was far too high and the   
   > >finger of suspicion pointed to the inter-stage coupling capacitor   
   > >feeding in leakage current from the preceding stage.   
   > >   
   > >I tested the capacitor, which was marked "4.7".  It read exactly 4.7k in   
   > >both directions on an ohm-meter !!!   
   >   
   > Was it a light blue Sanyo?   
      
   It was indeed!   
      
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
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