Fuzz Face issues

Choivert

I bought an older Dunlop fuzz face but the sound cuts in and out when engaged, it's worse on higher pitches and when i roll back the volume at 9 there is no sound at all. 

Choivert

There is a video at the bottom of this Imgur post along with a few more photos: https://imgur.com/gallery/mG6Is0E

The NKT275s in these are known to be General Manufacturing fakes. 

Kurtis

Battery OK?

Or could it be temperature? Germanium can be very sensitive. 

roberty

Yeah sounds battery-ish, or improper bias

Choivert

Tried two batteries, both tested with volt meter reading 8.5v and 8.9v, both power my homemade fuzz face and other pedals fine. 

These models don't have bias trim pots unfortunately. To test bias I need to check voltage at the third leg of transistor 1 and transistor 2? 

Our house is not crazy warm at the moment. I thought that germanium transistors mainly sounded better cooler and worse when warm? But I could try it again once we have had the fire on for a while. 

Kurtis

I'd be tempted to try a fresh battery, these kinds of circuit can be a bit fussy.

I don't think it's that it sounds better cold just that extremes (not even that extreme) can shift the bias. An internal trim is handy. 

Choivert

I managed to track this down to a poor solder joint on a resistor (the voltage at the collector of T2 was only -1.5v!). I've now managed to fix it and the voltage is -5.1v which is technically .1v under reccommended parameters but it sounds great. This resistor seems to be an extra compared with a traditional fuzz face circuit and I'm hoping to replace it with a trim point so I can bias the voltage there. 
Thanks for the help!