Path: ...!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: liz@poppyrecords.invalid.invalid (Liz Tuddenham) Newsgroups: sci.electronics.repair Subject: Re: Is it a capacitor, is it a resistor? Date: Sat, 16 Mar 2024 20:44:58 +0000 Organization: Poppy Records Lines: 29 Message-ID: <1qqj5m7.1k6ersdjyfwhsN%liz@poppyrecords.invalid.invalid> References: <1qqfgdv.1y9tmdayl1lntN%liz@poppyrecords.invalid.invalid> X-Trace: individual.net mU6SiIw7Kzje5viXkIeyuwrK/9/n2gfHCpnQmCdgcMNCVP09TD X-Orig-Path: liz Cancel-Lock: sha1:lLLjSr0gnCKUPEVto6Dpy0fmv20= sha256:RQZ6hMCqpjxOcZNmOFHtNvw+vBqQFDo6AfboU9Moo1M= User-Agent: MacSOUP/2.4.6 Bytes: 1855 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