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Boss CE-2B Bass Chorus pedal schematicThis old Boss CE-2B Bass chorus generates a very clean and transparent sound. It has almostthe same circuit as the CE-2, with only a few differences. The most significant difference is the

additional kno !E. "E#E"$ to control the lend of the direct and processed signal.

Fig. 1: Boss CE-2B Bass Chorus guitar pedal schematic diagram

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Fig. 2: CE-2B Bass Chorus board - component sideDifferences between CE-2 and CE-2B:

Symbol CE-2 CE-2B

VR4 - 250KC (E.LEVEL pot.)

C14 33nF 12nF

C26 470pF 220pF

C27 470pF 220pF

R53 100Ω 390Ω

R42 1kΩ 100Ω

D6 RD5.1EB (5.1V Zene) RD5.6EB3 (5.6V Zene)

D7 RD11EB (11V Zene) !5500" (400V#1$ %&o%e)

'1-'3 2!C732-"R 2!C2240"R  

LED !L*-135B L+-2,R*

Specifications%

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- & control knos% 'ate, (epth and E."evel- Connectors% Input, )utput, *C *daptor- +ignaloise 'atio% more than /dB !I01-*$- 'esidual noise% less than -//dBm !I01-*$- Input impedance% 34/ k)hm- )utput load impedance% more than / k)hm- 5a6imum input level% /dBm !//07$- 'ecommended *C adaptor% *C* +eries- Current draw% /m* !(C #$- 8eight% 3//g- (imensions!mm$% 4/!8$ 6 99!0$ 6 29!($- (imensions!inches$% 2-&3!8$ 6 2-3!0$ 6 9!($

ICs, transistors and diodes used in the Boss CE-2B ass chorus%

IC% :5399;(( !dual operational amplifier$IC2% T"/22C< !dual operational amplifier$IC&% 5&//4 !/23 stage BB($IC3% 5&/ !BB( driver$

=-=&% 2+C223/>' !< silicon transistors$=3-=;% 2+C39< !< silicon transistors$=% 2+?&/*-@ !+ilicon -channel Aunction field effect transistor$(, (2, (3, (9 and (;% +234& !switching diodes$(% '(9.EB& !9.# ener diode$(4% +99//> !3//#* rectifier diode$"E( diode% "-2;'<

CE-2/CE-2B differences

The CE-2B circuit is almost identical to the CE-2 with only a few differences. The most oviouschange is the additional 29/kD E."evel potentiometer inserted in series with '22 !34kD$. *lso, acomponent of the high-pass filter, the C3 capacitor, located Aust efore the mi6 control, ischanged from /./&&u1 to /./2u1. * CE-2B with the E."evel kno turned fully clockwise willsound almost like the CE-2, ut with the chorus effect applied to slightly higher freuencies.

Transforming a CE-2B into a CE-2 is simple. 1irst, change C3 !/./&&u1$ to /./2u1. The levelkno acts as a short if set to the ma6., so the removal is not necessary, Aust rememer to alwayskeep it turned fully clockwise.

If you want to completely eliminate the function of the level kno, short all its & pins together.*lternatively, you can remove the wires that go to it and solder the 34k !yellow, violet, orange,gold$ resistor directly in the oard.

There are other component changes you could make, ut they will not affect the uality of thesound. +ee the tale on the right for all the differences etween the two models.

Adjustment procedure for the CE-2B%

Turn the Rate kno fully counterclockwise !min.$, the E."evel to middle position and

the Depth kno fully clockwise !ma6.$. 1eed a 2//07, F&dBm sine signal into the input Aack.

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Connect an oscilloscope to the emitter of =& and turn #'& to provide centered operating point asshown in the diagram on the left.