I'm having an issue getting any sound (besides noise) out of an etched Rump Roast board that I purchased from Madbean. I've triple checked the wiring, solder joints and orientation of components. Q1 biases correctly to 4.5V at the drain. However, the drain of Q2 is at 9.5V and doesn't move when I turn the trimmer (T2). Any thoughts as to what would cause this problem? I didn't substitute any parts (using J201s) and I checked all the values of the resistors & caps with a DMM before soldering them on the board.
Thank you in advance!
Quote from: gtg975n on March 10, 2012, 05:36:18 PM
I'm having an issue getting any sound (besides noise) out of an etched Rump Roast board that I purchased from Madbean. I've triple checked the wiring, solder joints and orientation of components. Q1 biases correctly to 4.5V at the drain. However, the drain of Q2 is at 9.5V and doesn't move when I turn the trimmer (T2). Any thoughts as to what would cause this problem? I didn't substitute any parts (using J201s) and I checked all the values of the resistors & caps with a DMM before soldering them on the board.
Thank you in advance!
I would check again to make sure all three legs of the JFET are connected.
I actually had a similar problem a while back due to a faulty SIP socket. The sleeve was actually missing so one of the JFET legs made intermittent contact. It was odd because I'd get the correct voltage if it was leaning against the inner side, but it would go back to the rail voltage every time the JFET moved a little bit. The soldering was fine and all the components were right, it was just a defective socket.
Thanks for the tip, mine are socketed as well. I tested the three leads of Q2 and they're all connected to the circuit. I'm still stumped.
You may have a solder bridge or a faulty/erroneous part. What else have you done debugging thus far?
Jacob
I took a look again at the board next to the schematic and realized that R7 & C9 weren't making a good connection with ground. Re-soldered these connections and it works now ;D Thanks for the help. Seems like the builds that give me the most trouble are the ones I learn the most from.
Quote from: gtg975n on March 12, 2012, 02:15:52 PM
Seems like the builds that give me the most trouble are the ones I learn the most from.
That's the best thing I've read on this forum! That's exactly how you should feel.
Jacob