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From: John Robertson <jrr@flippers.com>
Newsgroups: sci.electronics.repair
Subject: Re: Is it a capacitor, is it a resistor?
Date: Thu, 14 Mar 2024 23:23:12 -0700
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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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