Mesa Bass 400+ Wiring Issue - please help!

[bw1985]

Hi all,

I recently recapped a Mesa Bass 400+ head, and have screwed something up. I'm not sure where the black and white wires should be connected to.
I thought I took ample photos of the wiring before removing the board, but I'm not sure what is going on here! These resistors also blew again, so I need to replace them.
When I received the amp, they were already blown and there was a bad hum present. I haven't been able to get it going since.

Any insight would be greatly appreciated!

Thanks!
-B

[Jon Snell]

The resistor IDs will tell you instantly what their function is.
Do your spare wires connect to them?
Could they be the heater centre tap point?

[bw1985]

The resistor IDs will tell you instantly what their function is.
Do your spare wires connect to them?
Could they be the heater centre tap point?

Yes they do, but I'm having trouble finding a good schematic as well for the 400+ (plenty for the 400).
This is what I have:

[Jon Snell]

OK, what is the value of them?
Wouldn't be these would it?
If they are, one wire on pin 7 and the other on pin 2 of the nearest Octal valve socket.

[bw1985]

OK, what is the value of them?
Wouldn't be these would it?
If they are, one wire on pin 7 and the other on pin 2 of the nearest Octal valve socket.

Thank you! So I have connected the 2 wires to pin 7 and 2 and everything seems happy. Checked voltages throughout and it looks healthy. However, now I'm back to where I was before.
The amp currently has zero output! I'm not even sure where to start. Any advice on this?

[Helmholtz]

Also see this other thread: https://music-electronics-forum.com/...-tube-question

The heater balancing resistor were most likely killed by a shorting tube.
Does your amp have the zener in the screen supply?