From: jrr@flippers.com   
      
   On 2024/03/14 1:56 p.m., 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 !!!   
   >   
      
   Can digital ohm-meters be fooled by ESR?   
      
   It does sound like a leaky cap mind you - and interesting that the   
   leakage matches the stamped uf value!   
      
   John :-#)#   
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