[Constantin]

No matter how I set the threshold or the makeup...

• the right channel always has 9db less output than the left channel
• only when I switch the unit off, both channels have identical output

I have changed cables and the position within the lunchbox.

Does anyone have a clue where to start measuring?

Thank you, Constantin

[JPK]

Can you check if you get the correct voltages ?
https://www.soundskulptor.com/forum/index.php?topic=3.msg3#msg3

[Constantin]

Hi JP,

All values are ok except these:

Channel 1 (I plugged the testconnector into channel 1)
input signal = 3VAC
Threshold on +15
Makeup on 0
Signal level (VAC) on TP2=1.4VAC


Channel 2 (I also plugged the testconnector into channel 2)
Input signal = 3VAC
Threshold on +15
Makeup on 0
Signal level (VAC) on TP7=2.05VAC, TP9=1.35VAC
DC voltage (VDC) on pin 1 (white dot) of U16 (-0.018V).

Input signal = 3VAC
Makeup on 0
Threshold on -15
DC voltage (VDC) on pin 1 of U16 (white dot) = -0.18VDC.

[JPK]

With Threshold at +15, is the meter resting at 0?

[Constantin]

Yes, it is resting at 0.

I also used solder with non-conductive flux (at least that is what Felder states on the website):
https://www.felder.de/products/electronic-applications/wave-soldering-selective-soldering/nige-solder-sn100ni-snag-sn100c/loetdraht-iso-core-clear-5552941030.html

[Constantin]

Hi JP,

I have bought 2-Propanol Alcohol and cleaned the PCB thoroughly. Both channels have the same output now. Sorry for keeping you busy with this thread. I was pretty sure that I had no problems with conductive flux, because Felder stated on their own website that the flux in their led-free solder was non-conductive. Now I am not sure if some solder particals might have stuck to the flux or what the problem might have been. I was pretty thorough in brushing the PCBs after assembly.

Well, lesson learned: always clean off flux, even if the producer advertises it as non-conductive and non-corrosive ("no clean").

Thank you for your support!
Constantin

[JPK]

Great news!