Troubleshooting

[StratDudeDan]

i am attempting to create a fetzer valve boost pedal.

schematics:

(the arrow going off to the left from the lower left pin on the switch connects to the 68k resistor below)

i've gone over the wiring and soldering many a time so far. the switch is an on/on. i'm using a stereo input jack for battery cutoff. all of the grouds are soldered to a single bus bar on the PC board i'm using. the battery polarity IS correct.

situation:

while the effect is switched "off," i get no sound, a hum if the volume of the pedal is about midway up.

when on, there's no boost or tone change, just some noise added.

question:

what's going on and how do i fix it?

[lovekraft]

First of all, get rid of the switch until you get the booster working - no reason to complicate the process. My first guess would be that you've got the FET leads mixed up (been there, done that! ). Check the DC voltage at each one of the FETs leads, and go over the layout one more time to check for miswiring, shorts, and opens. If you don't find anything obvious, post those voltages, and maybe a photo of your layout, and we'll work on it some more.

[javacody]

After the FET pinout, my second guess would be that you are missing a ground or have a bad connection to ground.

Also, how is the trim set? Have you tried messing with it?

[StratDudeDan]

First of all, get rid of the switch until you get the booster working - no reason to complicate the process. My first guess would be that you've got the FET leads mixed up (been there, done that! ). Check the DC voltage at each one of the FETs leads, and go over the layout one more time to check for miswiring, shorts, and opens. If you don't find anything obvious, post those voltages, and maybe a photo of your layout, and we'll work on it some more.

been over the FET pinout over and over again. i've gone through seven different mpf102's making sure it was right, putting them in every possible position, this one twice ('cause i'm 99% sure this is right). i don't have a VU meter, so it'll take some time to get that. a good friend of mine has all the crap and i just borrow it from him when i need it, so i'll post the voltages once i get ahold of him on monday. my layout is a little weird. i just made a bus bar out of a piece of wire for the ground, then soldered everything that went to ground directly to that, and then i used another bus bar coming out of the transistor in order to put the electrolytic cap and the 1k5 resistor on (it was easier than trying to put three leads all connecting at the same point).

as for the trim, it seems as though it does nothing. seriously...i don't get it...both while it's "on" and "off," the trim is just a little knob i turn...which is strange, because it's the same thing with the volume knob. it doesn't affect the volume...

ah...there must be a short somewhere. yes...i'll play with it, then return here on monday with my results.

and uh...you don't want to see pics of my layout on the board...alien spaghetti i believe is the term used often...