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how sensitive are germanium trannies?

Started by jtn191, September 07, 2011, 10:00:29 PM

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jtn191

My zombii stopped working after I carried it around in my backback for a couple days and since I got a dehumidifier. Are germs that sensitive to humidity?!?

dwstanford

Not usually, but i have seen them fail for apparently no reason.  Have you tried swapping transistors to see if thats the problem?  It may not be the trannies.  If you dont have another pair, I would probe the circuit first to see exactly where the problem is before purchasing another pair.

jtn191

I guess I should clarify and say that it's still kinda working but there isn't much fuzz anymore. I have to turn the fuzz/gain knob all the way up to hear any signal and then it's kinda just a germanium sounding boost...only with fuzzyness when I play loud

mgwhit

If you carried it around in your backpack for a few days, I would assume that it might be a physical/mechanical issue before I suspected humidity.  Have you tested voltages or taken a signal tester to the board yet?

dwstanford

Yeah, you could also have a bad solder joint, wiring issue, etc.  You should not have to turn the gain past about 10:00.  Turning it all the way up should be blowing your face off.  If the transistors are socketed, take them out and put them back in.  Check the board and wiring for any cold joints, shorts, etc.  If there were a bad joint, it may have been making a partial connection and then broken loose from the movement of carrying it around.  Is it run on a battery or on a power supply? 

slimtriggers

I would add that if they are in sockets, make sure they are still securely in the sockets.  Maybe one of the legs popped out.  I've had sockets that don't seem to want to hold on even in the best conditions :-\

dwstanford

Yeah, some transistor leads are actually smaller than the socket holes.  They can make a good connection at first and then disconnect after some use

jtn191

this was probably better suited for the tech help section but I'm good now...

I wobbled the transistors around a bit and turns out Q2 wasn't making sturdy contact.
thanks guys, this pedal has been the most finicky for me

mgwhit

In my experience, transistor leads never stay secure in socket holes.  I've got a Slambox, where the transistor will not stay secure in the socket no matter how I wedge it or tweak the leads.  Not really sure why I socketed it in the first place.  I've kinda given up on socketing unless I really think I want to monkey with the transistors later.  I just use one or two heat sinks and get in and off with the heat as fast as possible.  I've never damaged one.

It's been suggested to me on another board to put a dollop of solder on at least one of the socketed leads once I decide I'm happy with it.

I've noticed some transistors on Mouser are noted as having kinked leads.  Are those intended for socketing?

raulduke

The dollop of solder on one leg of the socket is a good idea.

I'll remember that one.