LaVache blowing transistors - need some help

[sonicboom]

Hi everyone,

New to the forum - first post.  I've built several MB pedals and they all sound really fantastic.  Thanks, Brian.

My LaVache build turned out great, but I've blown two transistors in it so far.  Anyone else had a similar problem?

I'm using a 2N3565.  The pedal seems to work fine for few hours and then it blows, usually when I engaging it (not after I engage it and am using it).  Is there a protection ckt. that I can use (e.g. a diode from collector to base)?

Signal path is from guitar to fuzz to Voodoo Labs amp switcher to LaVache.  The switcher has a buffer in it that does give it a small boost - nothing big though like a SHO.  How hot of a signal can it handle coming in? 

Thanks for any help.

[sonicboom]

Anyone?  Do you use a boost before your LaVache?  That would tell me that it's not a problem with the input signal.

Thanks.

[nzCdog]

I've built the Lavache and never had any problems like that. 

Read through this first
http://www.madbeanpedals.com/forum/index.php?topic=902.0

[Parra]

hi, i've built the Lavache with the 2n5088 and i run it with a Kingslayer (sometimes cranked) before and it works well, so i think that there is no problem on running boosts before it.
I don't know if the 2n3565 is more sensitive but you should check your board for wrong component values, also check the power that is going into the circuit.
It's a good chance to practice debuging on a small circuit like this, don't wait to do it on the bigger ones...good luck

[alanp]

What power supply are you using with it?

[sonicboom]

Thanks, guys.  I'm using a PP2+, and there are with no other pedals on except the amp switcher.

I'm pretty certain that everything is okay on the board and wiring, but it can't hurt to check again.  It sounds phenomenal as long as I don't really push the input too hard.

[midwayfair]

Given that the switching device you're using is made to switch amps, there could very well be an issue there. However, anything that would blow a transistor would probably also blow an amp, so I'd look in the Lavache for solder bridges and such, stick a multimeter on the input and see if there's something funky happening while switching, and post voltages to make sure there isn't something else bad going on.

It is excessively rare to have an effect put out even 10v peak-to-peak (and most are much lower ... the Lavache puts out less than 2v peak-to-peak). Even 25v is unlikely to kill a transistor.

[mgwhit]

Is this an etch or a fabbed board?  If you'd like to post transistor voltages or good pictures of both sides of your board, I'd be happy to check them out.