MXR Blue Box fourth transistor Q4 name?

[Benoitcarp]

Hi,
I have here a broken MXR blue bow with green pcb. Trasistor  (or regulator?) Q4 is broken and I can't seen what is written on it. Could anybody help me? This part doesn't show on classic blue box schematics...

Thank you fellars!

[Mark Hammer]

As far as I know, there are only 3 transistors in the circuit.

Is it possible someone decided to add a 4th one for some sort of buffering purpose?

[antonis]

Maybe it's some kind of Blue Fool version..
https://shop.pedalparts.co.uk/Blue_Fool_MXR_Blue_Box/p847124_12489300.aspx

[Mark Hammer]

If it IS that particular circuit, then the 4th transistor s apparently assigned to an added booster stage, in which case it can likely be any old NPN, assuming it conforms to the pinout.