I can't seem to get this one going.......I Went through about 40 Transisitors and matched sets up and i have a perfect matched set of 1.604v ( Kudos to Bill Bergman for sending me a Jfet Matcher :) ). I have signal in and out of bypass mode. I tried switching around the Transisitors and tweaking the Trimpot but still have no sound. Anyone got any ideas of what to check ? any voltages i should take? Thanks for any help in advance!
The first thing I look for is shorts and bad solder joints. Flip the board vertically and check the continuity b/w resistor leads and solder joints. Sorry I can't help much more but if it's not spitting then it's not a bias issue...
Quote. Anyone got any ideas of what to check ? any voltages i should take?
First, read the section of the Guitar Effects Debugging Page at GEO about starting up new effects. Lots of ideas there about what might be wrong and good first guesses.
Second, to cut it a bit short, read the DC voltages on every pin of every opamp and transistor and list them back. We can compare them to what they should be. The "should be" values are listed, at least in part, in the debugging page. Every amplifying opamp must have the +, - and output pins within a few millivolts of each other, and that level should be within millivolts of the reference voltage. The power supply pins should be ... at the power supply voltages by actual measurement.
Thanks guys. I have power getting to where it should be. Here are some readings :
Q 1:
S- 3.156
G- 3.152
D- 3.152
Q2:
S- 3.162
G- 3.136
D- 3.14
IC1:
1- 3.148
2- 3.154
3- 3.147
4- 0
8- 6.70
7- 3.157
6- 3.154
5- 3.015
IC2:
1-
2-
3-
4- 0
8- 6.64
7- 3.117
6- 3.125
5- 3.118
Pins 1-3 jump between O.L. and a reading .could this be the problem? I have to re-check my resistor values. Thanks for the help!
Q1 and q2 Voltages are almost identical from each ones DS And G pins...
Pin 8's of the OA's [dual ?] should be at V+ of battery? or very close to that...the battery looks to be very low..around shutoff for that OA?
I assume only the second half of IC2 is being used.
The other IC voltages ... I'm interested to hear others thoughts.
If the OA input responds to a source [I use my finger and a 'poking' conductor] louder than the OA output, it must be amplifying.
I'm with pete here. It looks like you have an extremely dead battery on your hands. According to the tonepad schem, your pin 8's should be connected directly to +9.
You may want to replace it and try again. If it still doesn't work, give us new readings.
Thanks for the replys guys.....MY tongue tells me its not dead though :) ......I'll try a fresh battery and check my resistors and report back. Thanks!