Amps and effects
A pretty rare vintage J&J phaser for some service
The box is in good condition and has the original packaging.
Bottom side of the circuit board.
And the component side.
The circuit contains six NEC741 opamps, a transistor emitter follower on the output stage, and four stages of phase shifting with 2SK68 j-fets.
The old tantalum capacitors got replaced with film and electrolyts, also added som filtering on the output stage to get the noice level down.
Service of a T.C Electronic Chorus/Flanger
The pedal came in for service with no output.
With the bottom lid of.
Removing the circuit board reveals the second circuit board.
Looking at the first circuit board on the component side. All IC:s has their markings grinded down except for the MN3007 BBD.
Top side of the second circuit board with one of the bad pots removed.
The pedal had several issues. Two bad potentiometers, one could be repaired the other had to be replaced. Bad solder joints on the input jack and the balance trim pot from the BBD’s outputs were bad. Sorting the issues out brought it back to life. An image with a new potentiometer installed.
The pedal is powered with 230VAC with a small transformer on the 1:st circuit board. Had it rebuilt for operation with a normal 9VDC supply.
