Vh4: red tube fault not ligting

[bronz79]

Hi to all,
I've got my first Diezel a vh4.
I use my vh4 with a G-system..yesterday making levels on the G-system
i saw (in the back of the vh4) v4 tube fault lighted on.
Today i've token off the v3 fuse and tested it on the v4..the red light shout
down and the el34 glows normally but,strange, v3 red light don't lit on.
I've checked the other and all without fuse (step by step) are lighting.
Now why v3 red light tube fault dont light on whitout fuse?
How can i solve?
Is only the light or can be the v3 tube fault system?
Thanks

Filippo.

 

[duesentrieb]

Unhook from mains and check the LED with a 9V battery.

 

[bronz79]

Unhook from mains and check the LED with a 9V battery.

Yes,but to do that should i extract the amp from the chassis?

 

[duesentrieb]

Yes.