Early Mark 1

[DC3 Gridlock]

I noticed that it doesn’t have the resistor on the plate of one of the output valves and the wire being wrapped around shielded cable wires.

Regards

Mark

Thanks, PM sent on my conversation with Mesa.

Should I be worried about the missing resistor and take it to my tech?

Thanks again.
Grid

 

[DavidMenke]

Thanks, PM sent on my conversation with Mesa.

Should I be worried about the missing resistor and take it to my tech?

Thanks again.
Grid

Best person to speak to at Mesa is Mike Bendinelli who has been there almost since the beginning. You could also send the amp to them, just the chassis, for cost, and they can go through and restore it to it's original state. The Mark series of amps may even be able to retro fit your amp into a new cabinet. (worth checking out) Or even a solid wood cabinet could be a choice. Those Mark one series are a keeper! Fix it up and play it for the next 50years.

 

[mark1406]

Thanks, PM sent on my conversation with Mesa.

Should I be worried about the missing resistor and take it to my tech?

Thanks again.
Grid

No I wouldn’t worry about it at all. Some amps had it and some amps didn’t.

Regards

Mark

 

[Don]

What does the Boost switch do?

 

[mark1406]

What does the Boost switch do?

The boost lifts the earth off the mid pot or in this case the mid resistor in the tone stack which removes the load presented by the tone stack and changes the tone of the amp.

 

[DC3 Gridlock]

The boost lifts the earth off the mid pot or in this case the mid resistor in the tone stack which removes the load presented by the tone stack and changes the tone of the amp.

I thought that the boost took the amp from 60 watts to 100 watts. I does sound better to my ears with it on.

 

[Don]

The boost lifts the earth off the mid pot or in this case the mid resistor in the tone stack which removes the load presented by the tone stack and changes the tone of the amp.

That's what I assumed, but I couldn't quite follow the wire.

 

[mark1406]

That's what I assumed, but I couldn't quite follow the wire.

Okay, I was talking with reference to my original Mark 1 amp. Given the position of the switch on your amp, I would agree that it is the 60/100 watt switch. This works by open circuiting the cathode to ground connection of two of the output valves.

Regards

Mark