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Marantz 7C noise

J

JCraig

New Member
I have a Marantz 7C preamp that recently made a sound like a car engine revving up. Quickly shut it down. After looking inside the preamp I noticed some stray voltage when using the high line input selected. When I switch to low line level it zero's out. Not sure where to look for bad resistors or capacitors or switch in that high line input circuit. Any help would be greatly appreciated.
thanks
 
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stray voltage where exactly?

I'm assuming by "low level" you mean the phono and tape head, vs high level aux, tuner, etc ? Just making sure I'm understanding the issue properly.
 
so the problem is only in high level then? That doesn't make a bunch of sense. The phono stage feeds through the line stage, but the line stage is in use for all inputs. Normally you'd see problems only in phono mode, or in all modes, not just in stuff going through the line stage.

Where and how much stray voltage are you seeing?

would also be useful to know what condition the unit is in. All original, fully restored, something in between?
 
gadget73 said:
so the problem is only in high level then? That doesn't make a bunch of sense. The phono stage feeds through the line stage, but the line stage is in use for all inputs. Normally you'd see problems only in phono mode, or in all modes, not just in stuff going through the line stage.

Where and how much stray voltage are you seeing?

would also be useful to know what condition the unit is in. All original, fully restored, something in between?
Click to expand...

Stray voltage= 0.35 ac volts measured on main preamp out to amplifier

the voltage will change if I lower the bass tone control to 0.1 ac volts, likewise if I use the high or low filter a slight variation in voltage.

the preamp is close to original the only changes were a new rectifier and volume control.
 
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