Valve Identfycation - Gibson Bass Combo

[Geoffb]

Hi Folks.

My friend a asked me the fix his Gibson Bass Head and has also supplied a circuit diagram for a GA-100.  Although the tube layout looks the same as the circuit diagram ( see attachment ), the valve in V1 position is NOT a 6EU7 as shown on the circuit,  a genuine 6EU7 to too large to fit in the valve base and the datasheet of a 6EU7 does not match the voltage reading I'm getting ( see attachments of amp and valve ). These are:

Pin 1 = 258v (suspect Anode)
Pin 2 =35.4v (suspect cathode)
Pin 3 = 72v ( suspect Cathode)
Pin 3&4 = 0v ( joined Heater)
Pin 5 =0v
Pin 6 = 334v (suspect cathode)
Pin 7 = 0v ( audio input from jack sockets)
Pin 8 =2v  ( suspect Cathode)
Pin 9 = (heater)

The above pin out is similar to an ECC83
The fault is reported a hum on the output and checking V1 is as far as I've got..
Can anyone identify this valve, or indeed if this amp is a GA-100?
Regards
Geoff.

[shooter]

V1 on almost every Gibs amp I fixed got replaced, socket included, I used  12AU7A.  from surfing looks like a GA100, schematics do show the eu7.  Good luck, they are a different beast but I like 'em hands down to ANY fender 

[sluckey]

The tube in your pic is a 7 pin tube. Maybe it is a 6AV6 or 6AT6?

[kagliostro]

If the tube in the photo comes from the amp, it may be one of the two V2 - V3 6BD6 tubes


Franco