Sound Skulptor forums

Build help and troubleshooting => SK25/SK99 Discrete Op-Amp => Topic started by: JPK on December 17, 2020, 11:47:34 AM

Title: In case your DOA doesn't work as expected
Post by: JPK on December 17, 2020, 11:47:34 AM

1. Check the usual suspects:

• Forgotten solder joint,
• Bad solder joint (reflow suspicious joints),
• Reversed components (diodes, transistors),
• Flipped transistors,
• Trim all the component leads as short as possible. Nothing must touch the PCB below.

2. Also:

• make sure R1 is not touching the vertical PCB and the diode D5,
• check you didn't flip the power transistors Q9-Q10,
• check that the 4 solders on each vertical PCB are making good contact,
• check you didn't reverse the LED (it must light up),
• check you didn't swap D4 (Zener) with one of the 1N914.

Other than this, the DOA's are very difficult to repair, I would recommend that you build a new one.