quick LaVache Troubleshoot

[jtn191]

so I fired up my new 'lil baby documented here http://www.madbeanpedals.com/forum/index.php?topic=3476.0

and nada...well almost nada. LEDs work fine and it seemed to initially just make noise--
but
when gain and volume are cranked, I get a quiet, weird underbiased fuzz kinda sound.

I audio probed it and found: on lug 3 of the Gain pot (when it's on full), I'm getting a loud, distorted signal and nothing on pins 1 & 2

Two and a half theories:
-I mixed up the pots--500k for Vol, 100k for gain?
-transistor is bad?
-a 2N3565's pinout is different from the 2N5088's

any insight is appreciated before I take this thing apart tomorrow

[jtn191]

anyone?

[jkokura]

There's an easy way to check if you're pots are backwards... Unmount the pots from the enclosure and check!

There's an easy way to check if your transistor is bad... Switch it for another!

There's an easy way to check if your pinot is wrong... Look up the datasheet!

I don't know otherwise. You can work all the regular debuggind steps if you want, but it sounds like you've done so already with the audio probing. Good work, nothing I can really add.

Jacob

[jtn191]

ok, well it was a very tight build and I was lucky to get the pots past the DC jack the first time...
I pried off each cap just enough to fit a shiny knife underneath to use as a mirror to read the pot values

<--100kB      and     500kB-->


so that should be right...
Pinout is right...
Maybe the culprit is grounded tops of caps...
I will audio probe some more...

must be a bad transistor  : http://www.madbeanpedals.com/forum/index.php?topic=1022.0

I used NOS fairchild 2n3565 from smallbear, I recommend testing them or socketing because I did get one bad one so far