I used all the listed values on the spreadsheet. No mods just C10 on offboard wiring (in anticipaton of the tone switch)
I am getting a blast of sound when guitar strings are plucked then it decays to nothing. Transistors are BC550cbu so pinouts are reversed. trannies and diodes are socketed. checked all diodes and cap C14 for polarity issues.
I reflowed solder on all the pads hoping to remedy a cold joint. Voltage from a 9 volt battery reads 8.91 at the board. Here are the transistor measurements:
Q1 E 28.3 mv
B .60 mv
C 3.71 V
Q2 E 27.7 mv
B .595 mv
C 5.78 V
Q3 E 26.8 mv
B .593 V
C 3.60V
Q4 E .274 V
B .81 V
C .273 V
Hope someone can point me in the right direction. I populated the board carefully and slowly, so I would be surprised if parts are switched somewhere.
Thanks all!
No sound? You didn't describe what is happening or not happening
Quote from: rcz53 on March 22, 2014, 12:38:40 AM
I used all the listed values on the spreadsheet. No mods just C10 on offboard wiring (in anticipaton of the tone switch)
I am getting a blast of sound when guitar strings are plucked then it decays to nothing. Transistors are BC550cbu so pinouts are reversed. trannies and diodes are socketed. checked all diodes and cap C14 for polarity issues.
I reflowed solder on all the pads hoping to remedy a cold joint. Voltage from a 9 volt battery reads 8.91 at the board. Here are the transistor measurements:
Q1 E 28.3 mv
B .60 mv
C 3.71 V
Q2 E 27.7 mv
B .595 mv
C 5.78 V
Q3 E 26.8 mv
B .593 V
C 3.60V
Q4 E .274 V
B .81 V
C .273 V
Hope someone can point me in the right direction. I populated the board carefully and slowly, so I would be surprised if parts are switched somewhere.
Thanks all!
Q4 is insanely low on the collector. You've got something wrong there. That low voltage is also causing your gating. It's possible you've mixed up R21 and R22 since they're right next to each other, and mixing them up would actually probably get that voltage.
Also, it's a good idea to stick to one tech help thread per build so that people don't post conflicting advice or duplicate efforts to help.
Mr Patton, you nailed it. R22 was 100k not 10k as intended. Although I used a DM on all resistors during assembly I obviously took a wrong reading. So much for populating the board slowly and carefully! The circuit works like a champ now. Many many thanks for your expertise.
Quote from: rcz53 on March 22, 2014, 05:15:38 PM
Mr Patton, you nailed it. R22 was 100k not 10k as intended. Although I used a DM on all resistors during assembly I obviously took a wrong reading. So much for populating the board slowly and carefully! The circuit works like a champ now. Many many thanks for your expertise.
woohoo! Glad you got it working. It's certainly an awesome muff variant.