Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hi everyone...
I have been look at some Marshall schematic and I recognize there is gnd symbol and 0V at the power supply section.
did they were different?
what does they mean?
thanks..

There is circuit common, often called ground informally.  There is earth ground, called earth in many places, but often called ground.

Most circuits have a common, but not all are grounded.  A transistor radio for example.  In many MArshall amps, the circuitry all has a common, the power supply "ground", but the chassis is not connected directly to that.  In those there is a low value resistor, like 10 ohms, a cap, and a pair of cross connected diodes, all those in parallel, between circuit common and chassis ground or earth.

it would be helpful to post the schematic you are looking at or at least linking us to it.

oh, my apologize. this is the schematic Im looking at
(http://www.drtube.com/schematics/marshall/3310pwr.gif)

Quote from: Enzo on December 18, 2016, 08:32:24 AMIn those there is a low value resistor, like 10 ohms, a cap, and a pair of cross connected diodes, all those in parallel, between circuit common and chassis ground or earth.

what does that circuit do?

Lower left on drawing is C7, it couples together 0v and chassis ground.  0v is the circuit common.  Across the center is a 0v line and on the left end it shows a chassis connection at the shield of the cable to the preamp.  Depending on the preamp circuit, this could mean various things.  But the basic difference is circuit common and the chassis ground.