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DIY For Audio
Power amp diagnostics / earthing advice: help needed
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<blockquote data-quote="LAV" data-source="post: 73483" data-attributes="member: 1123"><p>OK, on both channels I measure a resistance of 1k Ohms between the input (unbal.) and gnd, which is effectively R601 and R602. </p><p></p><p>I see 100 Ohms when I measure directly across the 33k input resistors (R603 and R604) on both channels, so there is something else effectively in parallel. Due to the position of the resistors I have not tried desoldering one of the legs, but it is unlikely that both of these would be OC.</p><p></p><p>The 10 Ohm resistors R664 and R663 are also fine...</p><p></p><p>All works fine until I put the mains earth back onto the power amp, which is when the hum returns and the voltage appears between the audio gnds. of the power amp and AVR ???</p></blockquote><p></p>
[QUOTE="LAV, post: 73483, member: 1123"] OK, on both channels I measure a resistance of 1k Ohms between the input (unbal.) and gnd, which is effectively R601 and R602. I see 100 Ohms when I measure directly across the 33k input resistors (R603 and R604) on both channels, so there is something else effectively in parallel. Due to the position of the resistors I have not tried desoldering one of the legs, but it is unlikely that both of these would be OC. The 10 Ohm resistors R664 and R663 are also fine... All works fine until I put the mains earth back onto the power amp, which is when the hum returns and the voltage appears between the audio gnds. of the power amp and AVR ??? [/QUOTE]
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DIY For Audio
Power amp diagnostics / earthing advice: help needed
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