I have a CE-2 Green Label. Taiwan. I haven't used it in years but I just took it out and noticed that my indicator light does not indicate when the chorus is engaged and a 9V power adapter is used. Works correctly using a 9V battery but not a power supply.
I have seen a video demonstrating the CE-2 where the pedal is using apower supply and the light is on when the chorus is engaged and a video where the light is off with the chorus engaged.
I took my Pedal to my tech and he was intrigued. He pulled out a schematic and found that there was a different resistor being used on the part of the circuit that switches between the battery and the power adapter.
The schematic calls for a 100 ohm resistor at R53 but there was a 400 (actually390 ohms) resistor.
R53 and diode D5 are on the negative side of the power adapter connector.D5 ensures the power adapter is the correct polarity. The battery negative terminal bypasses these two components. When using the adapter, pedal and LED operating current flow through R53 and the drop across R53 when it’s 390 ohms is large enough that voltage to the pedal falls below the minimum to light the LED. That minimum is set by D6, a Zener diode in the leg that supplies current to the LED.
Then he inserted the 100 ohm resistor into the circuit,
Guess what? The LED lights! Now when the chorus is engaged with the power adapter. The purpose of R53 seems to be to limit current when the adapter is of the correct polarity but its voltage is above the maximum set by Zener diode D7.
We wondered why this happened. The board should have had that 100ohm resistor but had the 400 instead. Factory error? An errant or left over resistor in the parts feeder? It got by QC. The 390 ohm resistor is the same type, intended for vertical mount, with an enamel insulated, bent lead. The board looked like the part was wave soldered along with most of the other components.
From our texts:
So I guess ‘only’ the Boss adapter would have worked IF the Boss adapter had a higher output than advertised, like 13 or so volts. Really, ANY 13+ volt adapter would work.
Now that the resistor has been changed, the schematic is what we expect from the pedal.
The circuit obviously works at 9V. There’s no requirement from sonic or operational considerations that the adapter be 12V or 11, or even 10 volts. There is a single polarity protection diode, that costs an ‘overhead of .6 volts. So any adapter voltage of 9.6v or better will give exact same results as a fresh battery. The battery ‘check’ function still works as before. The ‘wrong’ part (R53 on the schematic) is used only in the ground leg of the adapter.
The390 ohm resistor on the desk, the screwdriver tip is pointing to the new 100ohm part.
Pedal on!
Pedal off.
I have seen a video demonstrating the CE-2 where the pedal is using apower supply and the light is on when the chorus is engaged and a video where the light is off with the chorus engaged.
I took my Pedal to my tech and he was intrigued. He pulled out a schematic and found that there was a different resistor being used on the part of the circuit that switches between the battery and the power adapter.
The schematic calls for a 100 ohm resistor at R53 but there was a 400 (actually390 ohms) resistor.
R53 and diode D5 are on the negative side of the power adapter connector.D5 ensures the power adapter is the correct polarity. The battery negative terminal bypasses these two components. When using the adapter, pedal and LED operating current flow through R53 and the drop across R53 when it’s 390 ohms is large enough that voltage to the pedal falls below the minimum to light the LED. That minimum is set by D6, a Zener diode in the leg that supplies current to the LED.
Then he inserted the 100 ohm resistor into the circuit,
Guess what? The LED lights! Now when the chorus is engaged with the power adapter. The purpose of R53 seems to be to limit current when the adapter is of the correct polarity but its voltage is above the maximum set by Zener diode D7.
We wondered why this happened. The board should have had that 100ohm resistor but had the 400 instead. Factory error? An errant or left over resistor in the parts feeder? It got by QC. The 390 ohm resistor is the same type, intended for vertical mount, with an enamel insulated, bent lead. The board looked like the part was wave soldered along with most of the other components.
From our texts:
So I guess ‘only’ the Boss adapter would have worked IF the Boss adapter had a higher output than advertised, like 13 or so volts. Really, ANY 13+ volt adapter would work.
Now that the resistor has been changed, the schematic is what we expect from the pedal.
The circuit obviously works at 9V. There’s no requirement from sonic or operational considerations that the adapter be 12V or 11, or even 10 volts. There is a single polarity protection diode, that costs an ‘overhead of .6 volts. So any adapter voltage of 9.6v or better will give exact same results as a fresh battery. The battery ‘check’ function still works as before. The ‘wrong’ part (R53 on the schematic) is used only in the ground leg of the adapter.
The390 ohm resistor on the desk, the screwdriver tip is pointing to the new 100ohm part.
Pedal on!
Pedal off.
